There is no single federal law that requires a specific number of AEDs in a building. Instead, the number you need depends on building size, layout, and the round-trip walking time from any point to the nearest device. The American Heart Association recommends placing enough AEDs so that a rescuer can grab one and return to a person in cardiac arrest within 3 to 5 minutes.
No Federal Mandate, but Guidelines Exist
OSHA standards do not specifically address AEDs. There is no federal regulation telling building owners to install a set number of devices per square foot or per floor. What exists instead is a patchwork of state laws, industry standards, and best-practice guidelines from organizations like the American Heart Association.
State laws vary widely. As of 2022, 20 states plus the District of Columbia require AEDs in schools, and California mandates them specifically in schools that offer sports programs. Some states also require AEDs in health clubs, fitness centers, or government buildings. The specific number of devices is rarely spelled out in statute. Instead, laws typically require that at least one AED be “on-site” or “readily accessible,” leaving the details of placement to the building operator.
The 3-to-5-Minute Rule
The most widely used guideline for determining how many AEDs a building needs comes from the American Heart Association. The principle is simple: a rescuer should be able to walk to the nearest AED and return to the victim within 3 to 5 minutes. That means the one-way walk to reach the device should take no more than 1½ to 2½ minutes.
Every minute without defibrillation during sudden cardiac arrest reduces the chance of survival by roughly 7 to 10 percent. Emergency medical services typically take 8 to 12 minutes to arrive, which is why on-site AEDs exist in the first place. The 3-to-5-minute window is designed to deliver a shock before brain damage becomes likely.
To apply this rule, walk your building. Stand at the point farthest from where you’d mount an AED, and time how long it takes to reach that spot and walk back. If the round trip exceeds 5 minutes, you need an additional device. Repeat this exercise for every wing, floor, and isolated area until no location in the building falls outside that window.
How Building Size Affects the Count
A small office of a few thousand square feet with a single floor typically needs just one AED near the main entrance or a central hallway. A mid-size building of 50,000 to 100,000 square feet may need two or three, especially if it has wings separated by long corridors or locked doors that slow travel.
Large facilities like warehouses, convention centers, or corporate campuses often need significantly more. A 200,000-square-foot warehouse with aisles stretching hundreds of feet in every direction could require four or more units to keep any worker within that walking-time threshold. If your building has areas that are locked, gated, or otherwise restricted, treat each zone as its own coverage area. A locked server room on the far end of a floor, for instance, means the AED in the lobby may be functionally unreachable in time.
Multi-Story and High-Rise Buildings
Vertical distance complicates things. Research published in Circulation found that people who experience cardiac arrest on upper floors of tall buildings face longer delays and lower survival rates compared to those on the ground level. Waiting for an elevator, riding between floors, and navigating hallways all eat into that critical response window.
For buildings with three or more stories, the general practice is to place at least one AED on every other floor, or on every floor in high-occupancy buildings. In very tall buildings with relatively uniform foot traffic across floors, placing an AED inside or near the elevator bank can reduce average response distance. In buildings where most people congregate in the lobby or ground level, a lobby-based AED covers the highest-risk area more effectively. Many facility managers use a combination: one in the lobby and additional units on upper floors.
Stairwells are not a practical retrieval route for AEDs. If your building’s elevators are slow or frequently occupied, you may need more devices per floor to compensate for vertical travel time.
High-Traffic and High-Risk Areas
Certain spaces within a building deserve their own dedicated AED regardless of overall building size. Fitness centers and gyms see a disproportionate number of cardiac events due to intense physical exertion. If your building has an on-site gym, place an AED inside or immediately outside it. The same logic applies to cafeterias or large meeting rooms where dozens or hundreds of people gather.
Buildings that serve older populations, such as senior centers or certain healthcare waiting areas, also warrant tighter AED coverage. The likelihood of cardiac arrest rises with age, so shorter response distances matter more in these settings.
A Practical Way to Calculate Your Number
Start with a floor plan and mark every entrance, stairwell, and elevator. Then follow these steps:
- Identify high-risk zones like gyms, large gathering spaces, and areas with older or physically active populations. Each of these gets its own AED.
- Walk the farthest points on each floor. Time a brisk round trip from each corner or dead end to the nearest planned AED location. If any round trip exceeds 5 minutes, add a device.
- Account for barriers. Locked doors, security checkpoints, construction zones, and outdoor walkways between buildings all add time. Treat each side of a barrier as needing its own coverage.
- Add one per every two to three floors at minimum in multi-story buildings. High-occupancy floors should each have their own.
For a rough starting estimate: a single-story office under 10,000 square feet needs one AED. A 50,000-square-foot, two-story building typically needs two to three. A 10-story office tower with 500 or more occupants may need five to eight, depending on layout and how quickly elevators move. These are starting points. The walking-time test is always the final check.
Where to Mount Them
Placement matters as much as quantity. AEDs should be in visible, unlocked locations that anyone can reach without asking for a key or badge. Wall-mounted cabinets near main corridors, lobbies, break rooms, and elevator banks are the most common spots. Many cabinets include alarms that sound when opened, which helps alert others that an emergency is underway.
Avoid placing AEDs inside locked offices, behind reception desks, or in rooms that are only accessible during business hours. If your building operates 24/7 or has after-hours occupants, every AED should be reachable at all times. Signage matters too. Clear markers at eye level pointing toward the nearest AED help bystanders find the device quickly under stress, when people are least likely to remember where it’s stored.