Rack Location Labelling: Numbering, Labels, Scan Range

Rack location labelling in a warehouse ties every slot to its record in the warehouse management system, and a label that peels off or reads wrong becomes a mispick every time. Long range retro reflective labels now scan up to 15m away, which changes what belongs where. This blog walks you through numbering schemes, label types and scanning distance, starting with the storage and racking systems they sit on.

What is warehouse rack location labelling and why does it matter?

Rack location labelling is the system of coded, scannable labels fixed to each rack position so that every slot has a unique address the warehouse management system can read. Each label carries a location code as a barcode and as human readable text, and it is the physical anchor for the digital location record.

The stakes are data integrity, not decoration. Every pick, putaway and stock count relies on the physical label agreeing with the WMS location record, so a label that peels off, fades or carries the wrong code sends a picker to the wrong slot and corrupts the count. A mislabelled location is a systematic error that repeats on every transaction until someone finds it.

The label sits between the rack and the software. A code like A-12-03-B maps a physical beam position to a database record, and the bay, depth and level structure of the racking is exactly what that code describes. The label is where the warehouse layout and the system meet.

Treat labelling as part of the storage system, not an afterthought fitted on handover. A rack with no reliable location layer is a rack the software cannot trust.

How do you number warehouse rack locations?

With a hierarchical code that narrows from the widest zone to the exact slot, almost always aisle, then bay, then level, then position. A code such as A-12-03-B reads as aisle A, bay 12, level 03, position B, and every location in the building follows the same pattern so the address is unambiguous.

Consistency is what makes the scheme work. Each field uses a fixed number of digits with leading zeros, so bay 2 is written 02 and sorts correctly against bay 12 in the WMS, and a code that mixes A-1 with A-01 breaks the sort and confuses the scanner. The format is set once and applied to every label in the building.

The identifier standard sits underneath the internal code. Most warehouses run their own aisle bay level scheme for internal slots, while GS1’s Global Location Number is the international standard where locations are shared between companies, and GS1 says the GLN gives users “complete flexibility to identify any type or level of location required”. Even an internal scheme borrows the GS1 modulo 10 check digit to catch a misread.

Number to a single fixed pattern and never improvise a code at the rack. The scheme is a system decision made before the first label is printed, not a choice left to the installer.

Which way do you number bays, levels and aisle sides?

Left to right as you face the rack for bays, bottom to top for levels, and opposite sides of an aisle split into odd and even so a scanner knows which face it is reading. The numbering follows the picker’s path, not the drawing’s convenience.

Direction encodes the route. Bays run left to right along the aisle and levels count upward from the floor, so a picker walking the aisle reads a rising, ordered sequence and the WMS can route a pick path that does not double back. Odd numbers on one side of the aisle and even on the other tell the system, and the operator, which of two facing racks a location sits on.

Gaps in the sequence save a relabelling job. Numbering bays 01, 02, 05 rather than 01, 02, 03 leaves room to insert a new bay later without renumbering the whole aisle, which matters in a multi client warehouse layout where slots are added and reassigned often. The gap is cheap to leave and expensive to retrofit.

Number for the person and the truck that read it, not for the CAD file. A scheme that follows the pick path pays for itself in every shift.

What types of rack label are there?

Five that cover almost every warehouse: self adhesive labels, magnetic labels, retro reflective long range labels, cold store labels and overhead aisle or totem signs. Each is matched to where it sits and how it is read, not chosen as a default.

Self adhesive polyester labels are the standard for a fixed pick face. They carry a Code 128 barcode with the location code in large text above it, mount at or just below eye level for a handheld scanner, and stay put with a permanent adhesive on a clean beam. This is the workhorse label for a ground level position scanned at arm’s length.

The other four solve specific problems. Magnetic labels reposition without residue for racks that get rearranged, retro reflective labels carry the scan to a high beam, cold store labels survive a freezer, and an overhead aisle sign or a ground level totem gives orientation and long distance identification. The label follows the position; a single label type across a whole building leaves some locations unreadable.

Match the label to the location before ordering a roll. The pick face, the top beam and the freezer aisle each need a different label, and buying one type for all three fails two of them.

Which label do you need for high level locations scanned from the floor?

A retro reflective long range label, sized so a scanner reads it from the aisle floor rather than from a raised forklift. Retro reflective film returns the scanner’s light straight back to its source, which lets a barcode read at distance where an ordinary label would not.

Distance sets the specification. Retro reflective rack labels scan reliably from around 6m to 15m, roughly 20 to 50 feet, so a level four or five beam is read from the ground without raising an operator to it. The barcode has to be printed larger to carry that far, and GS1’s general specifications set a wider bar width, the X dimension, for location marking, at 1.016mm for a GS1 128 code.

The alternative removes the long range problem entirely. A ground level totem, a single sign at the base of the bay listing every level’s barcode stacked in order, lets a picker scan the right level from the floor with a standard scanner, which suits a multi level rack design where reaching every beam is impractical. The totem trades a long range scanner for a larger ground sign.

Read the top beams from the floor, by retro reflective label or by totem, never by sending a person up to them. Height is a scanning decision made at design, not a reach problem solved later.

What label survives a cold store or freezer?

A cold store label with a low temperature adhesive rated for the environment, or a magnetic label that needs no adhesive at all. A standard pressure sensitive adhesive fails on a cold, frosty or condensation covered beam, so the label lifts and the location is lost.

The adhesive is the whole problem. Freezer rated label adhesives bond down to around minus 30°C and hold on frozen steel where a standard label peels within weeks, which is why a cold store racking install specifies the label material at the same time as the racking. Applying a warehouse label in a freezer and expecting it to hold is the common and expensive mistake.

Magnetic labels sidestep adhesion altogether. A magnetic label clamps to the steel beam with no glue, works in a freezer where adhesives struggle, and lifts off cleanly when a location is reassigned, which suits a chilled area that gets re slotted. The trade is cost per label against reliability in the cold.

Specify the freezer label with the freezer racking, not after the first ones fall off. A lost cold store location is picked in a minus 25°C aisle nobody wants to search twice.

When should you use magnetic instead of adhesive labels?

Whenever the rack layout changes often enough that peeling and reprinting adhesive labels becomes a recurring job. Magnetic labels reposition cleanly without residue, so a warehouse that reslots seasonally or runs changing client profiles moves the label with the slot instead of scraping and replacing it.

The decision is about layout churn, not preference. A fixed installation that will hold the same slotting for years is cheapest on permanent adhesive labels, while a facility that rearranges beams or reassigns bays, such as one going through a re rack or expansion, spends less over time on magnetic labels that survive the change. The higher unit cost buys reusability.

Beam profile decides whether magnets hold. Magnetic labels grip a steel beam face well, but a rack with narrow or coated beams may not give a magnet enough purchase, so the beam is checked before the label type is fixed. A magnet on the wrong surface is a label on the floor.

Choose magnetic where the layout moves and adhesive where it does not. Paying the magnetic premium on a rack that never changes is spending on flexibility the site will not use.

How do rack labels connect to your warehouse management system?

Each physical label maps one to one to a location record in the WMS, so scanning the label tells the system exactly where a pallet is or should go. The label is the bridge between the steel and the software, and the mapping only works if the two never disagree.

The code is the shared key. The WMS holds a location record for every slot, the label carries that same code as a barcode, and a scan matches the physical position to the record for the pick, putaway or count. A location that exists in the WMS but carries no label, or a label with no matching record, is a slot the system cannot use reliably.

Validation keeps the mapping honest. A check digit built into the code lets the scanner reject a misread before it writes a wrong location, and a periodic label audit catches damaged or missing labels before they orphan a slot. GS1’s check digit method, the same modulo 10 used across its identifiers, is the standard way to build that validation into an internal code.

Keep the label and the record identical, and audit that they stay so. A WMS is only as accurate as the labels its scanners can actually read.

The label is the location, not a sticker on it

Rack location labelling is the physical half of your warehouse management system. The numbering scheme addresses every slot from aisle to position, the label type is set by where it sits and how far it is read, and the code maps one to one to the record the software trusts. A pick face takes an adhesive label, a high beam a retro reflective one, and a freezer a magnet or low temperature adhesive.

Send us your rack layout and we will map a numbering scheme and label specification for every location. Request a labelling plan.

Frequently asked questions

What is an aisle bay level location scheme?

It is the standard warehouse addressing method that numbers each location by aisle, then bay, then level, then position, giving a code like A-12-03-B. The scheme narrows from the widest zone to the exact slot, uses fixed digit lengths with leading zeros so codes sort correctly, and maps directly to the location record in the warehouse management system.

How far can a warehouse rack label be scanned?

A standard adhesive label is scanned at arm’s length, under 2m, while a retro reflective long range label reads from around 6m to 15m, roughly 20 to 50 feet. Retro reflective film reflects the scanner’s light back to its source, so a high beam on level four or five is read from the aisle floor without raising an operator.

Do cold rooms and freezers need special rack labels?

Yes. A freezer needs a label with a low temperature adhesive rated to around minus 30°C, or a magnetic label that uses no adhesive, because a standard label peels off a frosty beam within weeks. Specifying the cold store label at the same time as the racking prevents the lost locations that a failed adhesive causes.

Should rack labels use a barcode or a QR code?

A 1D Code 128 barcode is the warehouse standard for location labels, because it is fast to scan at distance and holds a location code cleanly. A 2D code such as QR or DataMatrix stores more data in less space and suits dense bin labels, but Code 128 remains the default for aisle bay level rack locations.

How do you label a rack that gets rearranged often?

Use magnetic labels, which reposition cleanly without residue when a beam moves or a bay is reassigned. A facility that reslots seasonally or runs changing client profiles moves the label with the slot rather than scraping and reprinting adhesive labels, and leaving numbering gaps such as 01, 02, 05 lets a new bay slot in without renumbering the aisle.