Class A vs. Class B First Aid Kits: Which Configuration Does Your Workplace Need?
ANSI Z308.1-2021 sorts workplace first aid kits into two classes. A Class A kit covers the injuries most workplaces actually see, including minor cuts, abrasions, minor burns, and eye irritation. A Class B kit carries a broader range of supplies in larger quantities for work environments that are more complex or higher risk.
Key Takeaways
- Your hazard assessment sets the class. Class is about the danger at your site, not the number of people who work there.
- Class describes contents. Type describes the container. Any container type can hold either class.
- Class B adds item categories a Class A kit doesn't carry, so a Class A refill pack won't bring a Class B kit to minimum fill.
- OSHA doesn't require a specific class. It requires adequate supplies to be readily available and points to ANSI as recognized guidance.
If you're reading this after an audit, or after an incident that exposed a gap, neither kit is better than the other. The question is which one your hazards call for, and what that answer changes the next time you order refills.
What do Class A and Class B first aid kits actually mean?
Class A kits are built around the injuries that show up most often across ordinary workplaces. Minor cuts and abrasions, minor burns, small eye injuries, the everyday stuff that gets treated and sent back to work.
Class B kits carry a wider range of supplies and deeper quantities of them, aimed at workplaces where the injury potential is more severe or the environment is more complex. More people, more machinery, more distance from help.
Both are complete and compliant as sold. Neither one is more "ANSI compliant" than the other, which matters because that phrase gets used loosely in product marketing and it doesn't obligate you to the higher tier. On the regulatory side, OSHA's 29 CFR 1910.151(b) requires that adequate first aid supplies be readily available, and OSHA references ANSI Z308.1 as recognized guidance rather than mandating a class. The full minimum fill lists for both classes are in our ANSI workplace first aid requirements guide.
Class is the contents. Type is the container.
This is the most common mix-up in the topic, and it costs people money.
Class tells you what goes inside the kit. Type tells you how the container is built and rated, covering things like wall mounting, portability, and water resistance across Type I through Type IV. The two are independent. Any type of container can hold either class of fill, and a compliant kit is labeled with both.
So when someone tells you that you need a Class B kit, they've told you nothing at all about the cabinet.
What decides which class your workplace needs?
A workplace hazard assessment decides it. Three questions drive the whole thing: what hazards exist at your site, what injuries have happened or could happen because of them, and what supplies would treat those injuries.
Headcount doesn't come into it. Class is about the danger, not the number of people. Z308.1-2021 says directly that basing kits and cabinets solely on the number of people in a work environment is inadequate, which rules out the 10-person and 50-person shorthand you'll still see on packaging. What headcount and site layout actually drive is how many kits you place and where they go. ANSI guidance points at keeping supplies within three to four minutes of the hazard, so a sprawling plant needs more cabinets than a compact one at the same class.
Five hazard indicators worth weighing
- Machinery and moving parts. Pinch points, conveyors, rotating equipment. These produce crush and laceration injuries that run past what a box of adhesive bandages handles.
- Heat or chemical exposure. Welding, furnaces, hot surfaces, corrosives. Burns and eye or skin contamination call for more burn dressing and more flush volume.
- Elevated work. Falls produce fractures and sprains, which is where splinting capability starts to matter.
- Cutting tools. Blades, saws, sheet metal, glass. Deep lacerations and serious bleeding.
- Delayed EMS response. Rural sites, large secured campuses, night shifts. The longer your people are on their own, the more the cabinet has to carry.
Weigh these as signals rather than adding them up as a score. One strong indicator can land you in Class B on its own. Several weak ones may not move you at all.
| Hazard indicator | Likely class | What you order |
|---|---|---|
| Office, retail, or light assembly, no significant machinery | Class A | Class A complete kit, Class A refill packs on a normal cycle |
| Machinery, conveyors, or moving parts on the floor | Class B | Class B complete kit, with tourniquet and splint confirmed present at every cabinet |
| Welding, hot work, or chemical handling | Class B | Class B fill, plus added burn dressing and larger eye and skin wash volume |
| Elevated work or fall exposure | Class B | Class B fill, splint stocked and replaced after any use |
| Cutting tools, blades, or sheet metal | Class B | Class B fill, with bleeding control supplies considered separately from the cabinet |
| EMS more than a few minutes out | Weigh upward | Whatever your assessment lands on, ordered deeper than minimum |
What does a class change do to your refills?
Class B isn't a bigger pile of the same items, and this is where reorders break.
Compare the two published minimum fill lists and the Class B list carries three things the Class A list doesn't name at all: a tourniquet, a splint, and a wider four-inch roller bandage. Quantities climb across the board too, but the added categories are the part that catches people out. You can order a Class A refill pack, restock the cabinet to the top, and still be short of Class B minimum fill.
That's why a class upgrade is a full reset rather than an ordinary cycle. The "Refill This Kit" section on the complete kit product page is built for the reset case, because it rebuilds a cabinet to the full published fill in one order. Complete kit refill packs handle that reset. Workplace first aid kit refill packs handle the months in between, when you're replacing what got used.
Worth being blunt about the underlying point: compliance is maintained, not purchased. A kit is compliant the day it ships and stays compliant only if someone replenishes it to minimum fill. Monthly inspection and restocking after any incident is what keeps the label honest. Our guide on how to restock your first aid kit covers that cycle, and the restock hub is where you rebuild an order from what you actually used.
Do you need a different cabinet for a Class B kit?
No, and a fair amount of upgrade budget gets spent as though the answer were yes.
Class determines contents. A standard white wall-mounted cabinet with enough shelf space for a Class B fill holds a Class B fill. Nothing in the class designation obligates you to new hardware.
Where this does get expensive is the closed-loop pattern. Some cabinets are built to accept only one supplier's inserts, sized and shaped so nothing else drops in cleanly. Once that cabinet is on the wall, your refill options narrow to whatever that supplier stocks. A class change then turns into a cabinet change, and the cost of the decision has nothing to do with the standard.
MFASCO refill packs are sized for standard cabinets, so moving from Class A to Class B changes what goes in rather than what's mounted. There's more on that in our cabinet restocking guidance.
What changed in the 2021 update?
The classifications themselves stayed put. The contents shifted, effective October 15, 2022.
- A foil blanket became required in both Class A and Class B kits.
- Hand sanitizer quantities increased in both classes.
- Class B now requires a military-style tourniquet. A general-purpose elastic band doesn't meet that.
If your kits predate the update and nobody has reset them since, they're short. Verified against our published ANSI Z308.1-2021 summary, reviewed August 2026.
How does a mixed-class site keep one supply process?
Plenty of operations run a Class A office and a Class B production floor in the same building. Nothing requires a single class across a site, since kits are labeled and stocked individually.
The move is to standardize the cabinet and vary the fill. If every location uses the same standard wall-mounted cabinet, then the difference between your front-office kit and your floor kits is the order, not the hardware. One supplier, one reorder list, two fills. MFASCO has been supplying Detroit-area manufacturers since 1966, when it started as Michigan First Aid Company, and multi-fill sites have been ordinary work the whole time.
If your assessment turns up a need neither standard fill covers, Make-A-Kit builds cabinet contents item by item.
Where a standard pack stops being the right answer
If you run one small location with genuinely low hazard, a single cabinet in a quiet office with no machinery on site, building a refill process around it probably isn't worth your time. Buying a complete Class A kit off the shelf when the current one gets thin is simpler, and it keeps you compliant. Refill workflows earn their keep across multiple cabinets, heavy usage, or a fill you've customized. One cabinet that gets opened twice a year isn't that case.
Additional Resources
- ANSI Workplace First Aid Requirements
- How to Restock Your First Aid Kit
- Workplace First Aid Cabinet Restocking
- Complete Kit Refill Packs
