Aisles, bays, levels, positions: the method for naming every location in your warehouse, taking the weight and the size of your products into account. With a generator that produces your full numbering scheme and exports it to CSV.
The guide prints without the navigation or the buttons.
A warehouse address is a set of coordinates: it describes a point in space, never what sits there. Built properly, it can be read, sorted and scanned for years without ever being changed.
Without addressing, product locations live in the heads of the long-serving staff. The new joiner searches, the temp calls for help, the Friday stand-in picks the wrong aisle. Travel and searching are the heaviest items in order picking, and they are exactly the two an effective addressing scheme cuts down.
Addressing is also the foundation for everything else. Cycle counting assumes you can count zone by zone. FIFO or FEFO picking assumes you know which batch sits at the front. Traceability assumes you can say where the goods were. None of these three holds up without named locations.
The one-question test
Pick a product at random and ask someone who was not there yesterday to go and fetch it, unaided. If they get it right first time, your addressing works. If not, this guide is for you.
From the broadest to the finest. You do not need all seven: keep only those that actually drive a decision.
The order is always the same, from the largest container to the smallest: site, zone, aisle, bay, level, position, depth.
| Segment | Common coding | What it designates, and the mistake to avoid |
|---|---|---|
| Site | LYO, ST1 |
The building or establishment. Only worth coding if you genuinely run several sites and addresses travel between them. Classic mistake: adding it “just in case” and lengthening every label for nothing. |
| Zone | PIC, RES, CHL |
A functional sub-area: picking, reserve, chilled, quarantine, dock. This is the segment that carries the constraints (temperature, security, hazardous goods). Classic mistake: confusing a functional zone with a product family. |
| Aisle | A, B, C or 01, 02 |
The travel corridor, not the rack. One aisle serves two rack faces, one on each side. Classic mistake: naming the racks instead of the aisles, which doubles the number of identifiers to remember. |
| Bay | 01 to 60 |
The section of racking between two upright frames, along the aisle. It is the unit of travel: you move from bay to bay. Classic mistake: numbering bays without regard for the direction of travel. |
| Level | A, B, C, D |
The height, from the floor upwards. Use letters so it is never confused with the bay number, which is numeric. Classic mistake: starting from the top down, which makes every plan counter-intuitive to read. |
| Position | 1, 2, 3 |
A slot often takes two or three loads side by side: the position says which one. Essential as soon as you want case-level FIFO or batch-level accuracy. Classic mistake: leaving it out, then discovering nobody knows which pallet to take. |
| Depth | 1, 2 |
Reserved for double-deep, drive-in or accumulation racking: the front load and the rear one. Classic mistake: using it on single-deep racking, where it means nothing. |
A well-kept three-segment scheme beats a sloppy seven-segment one. Start short, and add a segment the day its absence actually costs you something.
Every one of these rules comes from a mistake that gets paid for with a full relabelling. They cost nothing to apply beforehand, and everything to fix afterwards.
Write 01, not 1. Variable-length numbering is the number one cause of an incoherent pick path.
Do
Avoid
Why — Sorting is alphanumeric, character by character: “A-10” comes before “A-2” because “1” precedes “2”. Your picker then walks back to the other end of the aisle, on every single order.
Pick the hyphen and never change it. If all your lengths are fixed you can even do without one. But never a space.
Do
Avoid
Why — A space breaks CSV imports, barcodes and URLs. And every variant creates an invisible duplicate: “A-01-B” and “A 01 B” are two different locations to the machine, and only one to you.
Leave I, O and Q out of your letters. On a worn label, or read from a distance, they turn into 1 and 0. Watch out for the S/5, B/8 and Z/2 pairs too.
Do
Avoid
Why — A forklift operator who reads “O-01” instead of “0-01” picks from the wrong place, and the discrepancy only surfaces at the next stock count.
An address has to survive a barcode, a CSV file, a URL and an email unharmed.
Do
Avoid
Why — Code 39 and Code 128 character sets do not encode accents, and a badly encoded CSV import mangles them. You find out the day you switch tools.
Never name a location after the product, the family or the supplier that occupies it today.
Do
Avoid
Why — The product will move, the supplier will be replaced, the family will be reorganised. The address has to outlive all of it. An address that talks about its contents is an address waiting to be relabelled.
Every character widens the barcode and shrinks the font size that stays readable from a distance.
Do
Avoid
Why — A Code 128 barcode grows with the number of characters encoded. On a slot label read from several metres up on a truck, length becomes a genuine cause of read failure.
Odd on one side, even on the other, like street numbers. And carry the numbering on in the direction of the route rather than restarting at 01 with no logic.
Do
Avoid
Why — The pick path is built by sorting lines on the address. If the order of the addresses does not follow the real route, every order forces backtracking that nobody can make up for.
Leave spare numbers at the end of each aisle and keep at least one zone letter unused.
Do
Avoid
Why — A saturated scheme breeds workarounds — “A-BIS”, “01A”, “2.1” — that break sorting and force an exception into every one of your exports. Renaming a warehouse means relabelling, re-importing and running another stock count.
There is no universal format. There is a format proportionate to what you actually need to decide.
Only code a segment if it changes a decision. If you have one site, do not put the site in the address: your system already knows where it is.
Structure
AISLE-BAY-LEVEL
A few hundred locations, a single store
+ Short, memorable, dictated over the phone without error, very legible label.
− Does not distinguish two loads in the same slot, nor two zones.
When to choose it: Micro-business, workshop, shop stockroom, single-zone warehouse.
Structure
AISLE-BAY-LEVEL-POSITION
Several thousand locations
+ Designates a precise load: enough for case picking and for serious batch tracking.
− One more segment to key in, label and check.
When to choose it: Small and mid-sized businesses whose slots hold two or three loads side by side.
Structure
SITE-ZONE-AISLE-BAY-LEVEL-POSITION
Multi-site and multi-zone, no practical limit
+ An address is unique across the whole company, including from one warehouse to another.
− Long: every unnecessary segment is paid for on every label and every entry.
When to choose it: Several sites, temperature-controlled zones, strict picking / reserve separation.
If in doubt, take the standard format. It covers the vast majority of small and mid-sized warehouses and leaves room for the rest: the zone can live on the location record rather than in the address.
The address does not only say where. The level says at what height, and therefore with which equipment and how much effort.
Weight decides the height, bulk decides the width of the slot. Heavy items low down, the most-picked items at hand height, light items up high.
This is the highest-return rule in the whole addressing plan, and it costs nothing: you simply have to decide it before you label.
Upper levels — light, slow-moving items, or full reserve pallets handled by truck. Never frequent manual picking at height.
Intermediate levels — the comfortable reach zone, between mid-thigh and shoulder. This is where your most-requested items belong: no crouching, no arms above the shoulders.
Floor level — heavy, bulky, fast-moving loads. They are picked without lifting equipment and with the least possible lifting effort.
French standard NF X35-109 (based on a CNAMTS recommendation): 15 kg is the acceptable value for the largest number of employees, 25 kg the maximum admissible value under conditions, with a cumulative tonnage capped at 7.5 tonnes per person over 8 hours. Since the 2009 revision this threshold no longer distinguishes between men and women.
French Labour Code, article R4541-9 (regulatory): above 55 kg, habitually carrying a load is only permitted if the worker has been declared fit by the occupational physician, and never above 105 kg. The article also sets separate limits by gender.
These are French reference values for manual handling; outside France, check the equivalent national rules and the ISO 11228 / EN 1005-2 series. In every case they do not replace your own company risk assessment. Before locking an addressing plan onto weight criteria, have it reviewed by your health and safety officer.
A slot that is too tight blocks handling; a slot that is too wide wastes volume you are paying for. The two formulas below cover almost every case.
Slot height
slot height = load height + 100 mm safety clearance + beam height → then round up to the upright frame perforation pitch (75 mm)
The vertical clearance between the top of the load and the beam above must stay at a minimum of 75 mm: that is what allows the pallet to be engaged and withdrawn without catching.
Internal bay width
internal width = sum of load widths
+ 100 mm between two neighbouring loads
+ 75 mm on each side against the uprights
Worked example
2 EUR pallets side by side, handled on the 800 mm face: 800 + 800 + 100 + 75 + 75 = 1,850 mm internal width
The formats worth knowing
EUR / EPAL 800 × 1,200 mm · half-pallet 600 × 800 mm · ISO pallet 1,000 × 1,200 mm. The handling face, 800 or 1,200, changes the slot depth: decide it before you draw the plan, because it also drives the aisle width your trucks need.
An addressing plan that puts heavy items low down still does not excuse you from checking what each slot and each upright frame actually accepts.
The load notice
European standard EN 15635 governs the content of the load notice: the geometric characteristics of the racking and the maximum loads not to be exceeded at each storage level. Without a legible notice, nobody on the floor knows what the slot accepts — and nobody can be blamed for it.
The three levels of inspection it sets out
Immediate reporting of any impact, deformation or anomaly observed.
Weekly visual inspection by the operator.
Inspection by a technically competent person at least every 12 months, formalised in a written report and a prioritised action plan.
Do not size all your slots identically. Two or three templates — small, medium, large — covering the bulk of your items cost less than a uniform rack in which a large share of the volume stays empty. Code the template on the location record, though, not in the address: the template can change, the address must not.
Addressing gives you the coordinates. Slotting decides who goes where.
ABC classification tells you how far from the dock to store an item; weight and bulk tell you at what height. You need both.
Class A — the minority of items that account for the majority of picks: as close as possible to the despatch area and at reach height.
Class B — medium turnover: second ring, levels still reachable by hand.
Class C — low turnover: aisle ends and upper levels. You accept going there rarely and with equipment.
Cross the turnover class with the weight or volume class: the cell gives you the location to aim for directly.
| Turnover | Weight / volume | Location to aim for |
|---|---|---|
| A | Heavy or bulky | Floor level, first bays past the dock |
| A | Medium | Intermediate level, comfortable reach zone |
| A | Light and small | Intermediate level, in bins or a flow rack |
| B | Heavy | Floor level, second zone |
| B or C | Medium to light | Upper levels, secondary aisles |
| C | Full pallet | Reserve at height, handled by truck |
Rank your items by cube per order index: the volume occupied divided by the number of picks. The lowest indices — little space consumed, many picks — deserve the best locations. It is fairer than pure ABC, which ignores the space taken up: an item that moves often but ties up three slots does not necessarily deserve the front row.
None of these constraints can be traded against a productivity gain. Deal with them first, then optimise within what is left.
Product incompatibilities: food and chemicals kept apart, hazardous goods in a dedicated zone with containment.
Temperature control: ambient, chilled, frozen. The zone dictates, not the turnover.
Use-by and best-before dates: FEFO picking requires knowing which batch is at the front, so addressing down to the position and not just the slot.
Value and security: sensitive items in a locked zone, whatever their ABC class.
No-stacking or fragile loads: the constraint dictates the level, optimisation comes second.
Emergency access: never block a fire access, an exit or a sprinkler control to gain locations.
The question always comes up when it is time to lock the plan down. Here is what you need to decide.
Fixed addressing assigns a permanent place to each item. Random addressing lets the system put the load wherever there is space, and remembers where.
Every item has its location, always the same one.
+ An operator finds a product without looking at a screen, training is immediate, and an IT outage does not stop picking.
− Every item freezes its place even at zero stock: the fill rate hits a ceiling, and a new item forces a reorganisation.
The system assigns the most suitable free location at the moment of put-away.
+ Volume is used far better, a new item slots in without reorganising, and seasonal peaks absorb themselves.
− Everything rests on the accuracy of the recorded location: picking from memory is no longer possible, and a stock discrepancy becomes very expensive to track down.
The simple rule
Start with fixed addressing in the picking area — what you handle every day should stay memorable — and go random in the reserve, where the system guides you anyway. Only switch to fully random the day every movement is genuinely recorded as it happens, and not from memory that evening.
Enter your warehouse structure: the generator produces the full numbering scheme, the rack preview and the file to import.
Everything is calculated in your browser: no data is sent, nothing is stored. The naming checks from the rules above are applied automatically and flagged.
2 to 4 letters, for example PIC for picking or RES for reserve. Leave empty if you only have one zone.
Number of loads side by side in a slot. Enter 1 if you only have one load per level.
2 digits are enough up to 99 bays. Never drop to 1: sorting breaks.
“Odd on the left, even on the right” numbers both faces of the aisle, like street numbers: the number of locations doubles, since an aisle does serve two rack faces. Serpentine numbers continuously from one aisle to the next while alternating direction, so that sorting on the address follows the picker's real route.
Naming checks
First addresses
Last addresses
List truncated on screen: the CSV export contains every address.
The file opens straight into Excel or LibreOffice, and the Address column can be used as-is as the location in your stock management tool.
All of them have been seen on the floor. None can be fixed without walking the aisles again.
Sorting breaks at the tenth bay and the pick path becomes incoherent. It is the most common and the most costly trap, because it only shows up once everything is labelled.
Changing a scheme part-way means reprinting every label, restating every stock figure, and living with two systems in parallel for weeks. Lock the format down on one sheet, have it reviewed, and only then print.
“BOLT-ZONE”, “SMITH-RACK”, “PROMO-PALLET”: as soon as the product moves or the supplier changes, the address lies. And a lying address is more dangerous than no address at all.
Six or seven segments for a single-zone warehouse: the label becomes illegible, keying in endless, and nobody dictates the address correctly over the phone. Every segment must drive a decision.
A rack sized for the largest load stores air for all the others. Two or three templates are enough to win back a significant share of the volume you are paying for.
Dock, disputes, quarantine, returns, floor-stacked bulk, flow racks: if they have no address, the stock sitting there disappears from the system. That is where most unexplained stock discrepancies are born. Give them an address like everything else: DOCK-01, DIS-01, QUA-01.
Between the pick and the load, the goods are somewhere. Without a transit location they are either already shipped or still in stock — and both are wrong.
A slot label is read from a truck, several metres away, sometimes against the light. Plan the font size, the mounting height, the contrast, and a barcode short enough to stay dense. Labels for upper levels should be the long-range type.
Allow half a day of preparation for a small or mid-sized warehouse, and a day of labelling with two people.
Measure: number of aisles, bays per aisle, levels, loads side by side. Note the locations outside the racking and the constraints (cold, hazardous goods, locked zone). Do not work from the architect's drawing, it never quite matches.
Deliverable: A dimensioned sketch of the warehouse, zones included.
One format, one page: the structure, the separator, the number of digits, the excluded letters, the direction of numbering. Have it reviewed by the person who picks orders every day, not only by management.
Deliverable: A one-page numbering specification, dated and approved.
Use the generator on this page: it applies the naming rules, flags the anomalies and exports the full list to CSV.
Deliverable: The CSV file of every location.
Pull 6 to 12 months of pick history, classify into ABC, cross with weight and bulk, then assign. Deal with the non-negotiable constraints first, and optimise within what is left.
Deliverable: The product / location assignment for the picking area.
Slot labels with the address in plain text and a barcode, mounted at a constant height. Add aisle markers visible from a distance, at the start and end of each aisle. Check the scanner reads them from the actual working position, not from the office.
Deliverable: A labelled warehouse, with scanner reads verified on a sample.
Import the list of locations, then assign the existing stock. This is the moment a clean format pays off: a consistent list imports without touch-ups.
Deliverable: Locations created in the system, with stock attached.
Count everything once, location by location, so you start from an accurate base. Then train: 30 minutes is enough if the scheme is logical. The real test is having an order picked by someone who was not part of the project.
Deliverable: Accurate stock at the cut-over date, and a self-sufficient team.
The terms you will meet in quotations, standards and software — with their French equivalent.
| Term | French | Definition |
|---|---|---|
| Aisle | Allée | Travel corridor between two rack faces. It is the aisle that gets named, not the rack. |
| Bay | Travée | Section of racking between two upright frames, along the aisle. The picker's unit of travel. |
| Level | Niveau | Storage tier within a bay, counted from the floor upwards. |
| Slot | Alvéole | Storage cell bounded by two beams and two upright frames, on a given level. |
| Beam | Lisse | Horizontal member carrying the loads of one level. Its height goes into the slot calculation. |
| Upright frame | Échelle | Vertical member of the racking. Its cumulative permissible load caps the total stacked over the full height. |
| Load notice | Plaque de charge | Mandatory notice stating the racking geometry and the maximum loads per level (EN 15635). |
| Random storage | Adressage banalisé | Assignment mode where the system picks the most suitable free location instead of a fixed place per item. |
| Slotting | Slotting | Deciding which items go in which locations, crossing turnover, weight, volume and constraints. |
| FIFO / FEFO | FIFO / FEFO | First in, first out / first expired, first out. FEFO requires knowing the batch present at each position. |
| Cube per order index | Indice COI | Volume occupied divided by the number of picks. Sorted ascending, it identifies the items that deserve the best locations. |
| Golden zone | Zone de préhension | Comfortable height band, between mid-thigh and shoulder, where the most-requested items belong. |
| Stacking | Gerbage | Placing loads on top of one another. Some loads carry a no-stacking restriction that dictates their level. |
| Flow rack | Rack dynamique | Roller racking where the load advances by gravity: FIFO is mechanical, and picking always happens at the front. |
| Drive-in racking | Drive-in | Accumulation racking the truck drives into. Very dense, but reaching the back means removing what is in front. |
| Double-deep | Double profondeur | Two loads one behind the other in the same slot: space gained in exchange for access conditional on the front load. |
The aisle is the corridor you walk down. The bay is the section of racking between two uprights, along that aisle. The level is the tier, counted from the floor upwards. An address such as A-05-C therefore reads: aisle A, fifth bay, third level.
Letter them, starting with A at floor level. That avoids any confusion with the bay number, which is numeric. If you prefer digits, at least keep a clear separator and the same number of digits everywhere.
Aim for a dozen at most. Beyond that the barcode lengthens, the label font shrinks and reading from a distance on a truck becomes a gamble. A three or four segment format covers the vast majority of small and mid-sized warehouses.
Divide the floor into marked zones, then into load-sized locations, and number them exactly like bays: BLK-A-01, BLK-A-02. The level becomes unnecessary and everything else in the method applies unchanged.
The limit does not come from the level but from the racking: the load notice gives the maximum permissible load per level and per upright frame. For manual handling, French standard NF X35-109 sets 15 kg as the acceptable value and 25 kg as the maximum admissible under conditions; the French Labour Code requires an occupational physician's opinion above 55 kg. Outside France, check the equivalent national rules, and have your thresholds validated by your health and safety officer.
Yes, but zone by zone and never half-way. Deal with a complete zone in one go: new labels, re-import of the locations, stock count of the zone. What you must avoid at all costs is two schemes coexisting in the same aisle for weeks.
Fixed in the picking area, random in the reserve. Fixed keeps picking memorable and survives an IT outage; random densifies the reserve, where the system guides you anyway. Fully random assumes every movement is recorded as it happens.
The file generated here can be used directly as locations in GSE-Web, which can also print slot labels with their barcode or QR code. If you would like to talk it through before you start, the conversation is free and without obligation.
About this resource
This guide is published by KLS-Concept, the publisher of GSE-Web, stock management software for small businesses and vocational schools. The method described applies to any tool, including a plain spreadsheet: it depends on no particular software. Free to use, including in training.
Published on 4 September 2026.