Hazardous substances must be stored in a compliant cabinet under the Control of Substances Hazardous to Health (COSHH) Regulations 2002 — but a question we are asked constantly is a practical one: what size COSHH cabinet do I actually need? Buy too small and you end up with bottles stored on the floor or substances that should be segregated crammed together. Buy too large and you waste floor space and budget. This guide explains how COSHH cabinets are sized, the capacity figure that really matters, and how to match a cabinet to your inventory.
How COSHH cabinets are sized
COSHH cabinets are quoted in three dimensions — height × width × depth (H × W × D), in millimetres. Depth is usually fixed around 460mm so the cabinet fits against a wall or under a bench; the real choice is height and width, which together set your shelf area and the number of shelves. As a rough guide the UK market falls into four bands:
| Band | Typical size (H × W × D) | Best for |
|---|---|---|
| Under-bench / compact | ~700–900mm high | A handful of small containers at a workstation |
| Mid floor-standing | 1200mm high × 900mm wide | A workshop or department’s day-to-day chemicals |
| Large floor-standing | 1800mm high × 900mm wide | Several shelves of stock; the most popular size |
| Extra-large / wide | 1800mm high × 1200mm wide | High volumes or bulky containers needing segregation |
Our GPC CoSHH Security Cupboards are made in exactly these sizes — 1200H or 1800H, in 900mm or 1200mm widths, all 460mm deep — constructed from welded 1.5mm steel with a seven-lever anti-pick lock, full-length concealed hinges and an adjustable spill-retaining sump in the base.
The capacity that really matters: the sump
Cabinet height tells you how much you can stack; the figure that keeps you compliant is the sump (bund) capacity in the base. A COSHH or flammables cabinet has a leak-tight tray underneath the lowest shelf so that if a container fails, the liquid is contained rather than reaching a drain. As a working rule the sump should hold at least 110% of the volume of the largest single container, or 25% of the total volume stored — whichever is greater. So before you choose a size, add up the litres you intend to store: that number, not the headline dimensions, often decides whether you need the larger cabinet.
Wall-mounted, under-bench or floor-standing?
Smaller wall-mounted and under-bench cabinets suit a single workbench or a small quantity of substances kept close to the point of use. Floor-standing cabinets — 1200mm and 1800mm high — are the workhorses for stores, workshops and goods-in areas where stock is held in volume. If you need to keep incompatible substances apart (for example acids away from flammables, or pesticides separate from general chemicals), it is usually better to run two or more dedicated cabinets than one large shared one. Our hazardous storage range includes dedicated acid, pesticide/agrochemical, petroleum and highly flammable cabinets for exactly that reason.
How to choose the right size in five steps
1. Inventory your substances. List what you store and the total litres — this drives both shelf area and the sump capacity you need.
2. Check segregation. Decide what must be kept apart; that may mean several smaller cabinets rather than one.
3. Size the sump first. Apply the 110%/25% rule to your largest container and total volume.
4. Measure the space. Confirm footprint, door swing and a sensible height for handling — an 1800mm cabinet gives more shelves but reaching the top shelf with heavy containers is harder.
5. Allow for growth. Buying one size up is cheaper than replacing a cabinet that’s full within a year.
Frequently asked questions
What size is a standard COSHH cabinet? The most common floor-standing size in the UK is 1800mm high × 900mm wide × 460mm deep, giving several adjustable shelves. Mid-size cabinets are typically 1200mm high.
What are the large COSHH cabinet sizes? Large and extra-large cabinets are usually 1800mm high in 900mm or 1200mm widths; double-door wide models give the most shelf area for high-volume or bulky stock.
Is there a minimum size required by law? No — COSHH does not set a fixed size. It requires that hazardous substances are stored safely and contained. The practical constraint is that the cabinet must hold your stock and provide adequate sump capacity.
Can I wall-mount a COSHH cabinet? Smaller cabinets can be wall-mounted or sited under a bench close to the point of use; larger volumes need a floor-standing cabinet fixed and sited away from exits and ignition sources.
For the full legal picture see our COSHH cabinet requirements compliance guide, and if you are deciding between cabinet types read flammable storage cabinet vs COSHH cabinet. Browse sizes in the COSHH cabinets and hazardous storage collections.
This guide is general information, not legal advice. Storage decisions should follow your own COSHH risk assessment.