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How many AEDs does your building need?
- Updated · August 2026
EMS-assessed OHCA · AHA
~70%
American Heart Association
7-10%
AHA time-to-defib data
50
Pick your building type, square footage, and floors to get a planning estimate instantly.
- Quick answer · The 30-second rule
Most facilities need at least one AED. The moment a building adds a second floor, a detached structure, a high-risk zone, or a floorplate beyond roughly 22,000 square feet, a single unit cannot reach every corner inside the AHA 3-minute survival window.[1]
- 1 AED per facility (baseline)
- +1 per additional occupied floor
- +1 per detached building
- +1 per high-risk zone (gym, pool, machinery, child area)
- +1 per every ~22,000 sq ft of indoor coverage (planning estimate; validate by timed drill)
- •Coverage is about response time, not floor area: the goal is a shock within about three minutes of collapse, which drives how many units you need and where they go.
- •Plan by walking distance and layout: multi-floor or spread-out sites usually need more than one AED.
- •These are planning estimates, not a legal minimum: check your AED laws by state for any mandate.
- Coverage planning ranges
How much area can one AED cover?
| Building type | Planning range per AED | Why |
|---|---|---|
| Open warehouse / factory | ~30,000 sq ft | Straight aisles, few obstructions; machinery zones add risk-weighted units |
| Restaurant / retail | ~25,000 sq ft | Open layouts, moderate fixtures |
| Church / worship | ~25,000 sq ft | Long corridors, locked rooms; balcony seating adds a unit over ~500 seats |
| Office / corporate | ~22,000 sq ft | Cubicles, corridors, conference rooms |
| School / daycare | ~20,000 sq ft | Multi-wing layouts, slower mixed-age population |
| Hotel / hospitality | ~18,000 sq ft | Long corridors, elevators, locked guest rooms |
| Healthcare / clinic | ~15,000 sq ft | Vulnerable population, wings, security doors |
| Gym / fitness | ~10,000 sq ft | SCA risk up to ~17x during exertion[5]; tightest coverage of any facility |
- Worked examples
What the estimate looks like in real buildings.
Warehouse · 5,000 sq ft · 1 floor
1 AED
Office · 50,000 sq ft · open plan
3 AEDs
School · 60,000 sq ft · 2 stories
4 AEDs
Gym · 8,000 sq ft · cardio + weights
2 AEDs (3 with pool)
Guidance by industry
Placement quick-reference for the six most common facilities.
K-12 · mandated in most states
Schools
One per floor
Offices
Tightest coverage
Gyms
Balcony over 500 seats
Churches
One per guest floor
Hotels
90-second work cells
Warehouses
- Placement strategy
Where should the first AED go?
- 1 · Main entrance or front desk. Permanent staffing, fastest line of sight, often the only 24/7-supervised spot.
- 2 · Highest-risk zone. Gym, pool deck, production floor, sanctuary, child area. Risk-weighted beats square-footage-weighted.
- 3 · Largest unguarded space. Highest occupancy, longest walk from the first two units.
- 4 · Each detached building. Walking outside between structures burns the 3-minute budget instantly.
- 5 · Each additional floor. Stair or elevator transit is 60 to 90 seconds each way; one per occupied floor.
- The science · time = survival
Why placement matters more than ownership.
01
The 3-minute window
02
Square footage alone fails
03
Walking-speed baseline
04
OSHA guidance
- Compliance vs coverage
Why the survival target beats the compliance floor.
Many states mandate AEDs in specific facilities: K-12 schools and fitness centers most commonly. Statute language and counts vary by state, so verify yours on the 50-state AED law tracker before procurement.
Compliance keeps you from being cited. The AHA 3-minute target is what moves survival: roughly 70 percent when the shock lands inside 3 minutes versus about 20 percent at typical EMS response times.[1] Plan to the survival target, then confirm the statute box is ticked.
Got the count · now pick + budget
Coverage is step one. Model and budget are steps two and three.
Step 1
Find Your Perfect AED
60-second quiz, 4 questions, one personalized pick plus an alternate from FDA-approved models. No email required.
Step 2
AED Cost Calculator
True 5-year and 10-year ownership cost: device, pads, batteries, cabinet.
Deep dive
Buyer's Guide + Brands
Long-form guidance plus every brand we review: Philips, ZOLL, LIFEPAK, HeartSine, Cardiac Science, Defibtech.
- Common questions
Frequently asked questions.
How many AEDs do you need?
At least one per facility, plus one per additional floor, one per detached building, one per high-risk zone, and more units as floorplates pass roughly 22,000 sq ft. Treat every output as a planning estimate and validate with a timed walking drill.
How many AEDs do you need?
The AHA program target: collapse to first shock in about 3 minutes, covering the run to the AED, the run back, pad placement, and the shock.[1] Survival falls 7 to 10 percent per minute of delay.
What is the 90 second rule for AED?
Program shorthand: keep one-way retrieval to roughly 90 seconds of brisk walking so the full round trip stays inside the 3-minute window. It is the same target expressed one way instead of round trip.
How many AEDs does a 50,000 sq ft office need?
Plan three: 50,000 ÷ ~22,000 rounds up. Reception, elevator banks, largest open area, then drill to confirm; badge doors and corridors move the number.
How many AEDs does a school need?
A 60,000 sq ft two-story school typically plans four: per-wing coverage plus the gym and cafeteria, and a fifth for detached fields. Verify your state mandate on the tracker and see the schools guide.
How many AEDs does a gym need?
The tightest planning range of any facility, about one per 10,000 sq ft: exertion raises SCA risk up to ~17x.[5] An 8,000 sq ft gym plans two on the floor; a pool deck always takes its own.
Can one AED cover multiple floors?
Plan one per occupied floor. Stairs or elevators consume 60 to 90 seconds each way, which alone breaks the 3-minute round trip.
Where should I mount an AED?
Unlocked cabinet, ~48 inches high, signage visible from 50+ feet, never behind a key or badge. First at a staffed entrance, second in the highest-risk zone.
How often should AEDs be inspected?
Monthly visual checks of the readiness light and pad/battery dates plus the manufacturer’s annual routine; modern units self-test daily. Plan replacements with pads explained and batteries explained.
- Methodology and sources
Every calculation traces to a primary source.
- American Heart Association: 3-minute collapse-to-shock program target; survival decline of 7 to 10 percent per minute of delay.
- AHA Heart Disease and Stroke Statistics: more than 350,000 EMS-assessed out-of-hospital cardiac arrests per year, US.
- FHWA: pedestrian walking-speed standard of 4.4 ft/sec used in coverage timing.
- OSHA 29 CFR 1910.151 and OSHA Publication 3185: workplace medical readiness and AED program endorsement.
- Albert CM et al., NEJM 2000: SCA risk up to ~17x during vigorous exertion in habitually inactive individuals.
- American Red Cross: AED program and training guidance.
- FDA Premarket Approval (PMA) database: approval status for every model referenced by our tools.