Exit Sign Spacing Requirements (OSHA & NFPA 101)

OSHA exit sign spacing rule (1910.37)

Federal OSHA addresses exit sign spacing through two clauses in 29 CFR 1910.37(b):

• 1910.37(b)(4) — Direction of travel: If the direction of travel to the exit or exit discharge is not immediately apparent, signs must be posted indicating the direction. The line of sight to an exit sign must be clearly visible at all times.
• 1910.37(b)(2) — Every exit marked: Each exit must be clearly visible and marked by a sign reading "EXIT."
• 1910.37(b)(3) — No obstructions: Each exit-route door must be free of decorations or signs that obscure the exit.

OSHA does not state a hard maximum spacing in feet. The functional test is whether an occupant on the exit route can always see a sign and always knows which direction to travel — not whether signs are placed at a specific interval.

The 100-foot spacing benchmark (NFPA 101 + UL 924)

Most authorities having jurisdiction (AHJs) and local fire codes adopt NFPA 101 Life Safety Code and UL 924 (Standard for Emergency Lighting and Power Equipment) as the technical standard for exit sign placement. Together they produce the practical 100-foot benchmark:

• UL 924 viewing distance: Listed exit signs carry a rated viewing distance — most are listed for 100 feet. That distance is the effective cap for sign spacing on a straight, unobstructed corridor.
• NFPA 101 §7.10.1.5: Requires signs to be "clearly visible" along the path of travel and supplemental directional signs to be provided wherever the route is not obvious.
• Decision points: At every corridor intersection, turn, or branching point, a sign must appear before the ambiguity — not after. A 100-foot straight-corridor spacing may need to be cut shorter if a turn occurs at 60 feet.

For your evacuation map, mark exit sign locations at every turn and at approximately 100-foot intervals on long corridors. This makes the map useful for inspectors and for training employees on the evacuation routes. Use the free egress map generator to place exit sign icons on your floor plan automatically.

Exit sign mounting height

OSHA 1910.37 specifies the letter dimensions for EXIT signs but does not set a universal mounting height. Mounting height requirements come from the adopted building and fire code:

• IBC §1013.1: The bottom of exit signs must be not less than 80 inches (6 ft 8 in) above the finished floor.
• NFPA 101 §7.10.1.3: Allows signs to be mounted on the door, above the door frame, or suspended from the ceiling — wherever they are "clearly visible" along the path of travel.
• High-smoke environments: Some jurisdictions require low-level egress path marking (photoluminescent strips or low-mounted signs below 18 inches) in addition to standard overhead signs in high-rise stairwells and certain occupancies.

Confirm the required mounting height with your local fire marshal or AHJ. Show sign locations on your posted evacuation map — this also documents the installation for inspection purposes.

EXIT letter size and illumination requirements

These are the only two numerical thresholds OSHA 29 CFR 1910.37(b) sets for exit signs:

• Letter height (1910.37(b)(7)): At least 6 inches high with principal strokes at least 3/4 inch wide.
• Illumination (1910.37(b)(6)): At least 5 foot-candles (54 lux) on the sign face by a reliable light source. Self-luminous signs must achieve at least 0.06 footlamberts (0.21 cd/m²).

UL 924 listed signs that pass the standard are accepted as meeting the OSHA illumination threshold when properly installed with the specified power source. Signs must also remain illuminated during a power failure — the 90-minute backup requirement comes from NFPA 101 §7.9 (emergency lighting), enforced by most local fire codes.

Common exit sign citation errors

1. No sign where direction isn't obvious — a corridor turns and no directional sign is placed before the turn (1910.37(b)(4)).
2. Line of sight blocked — inventory, shelving, or hanging displays interrupt the clear view to the next sign (1910.37(b)(4)).
3. Undersized lettering — EXIT letters under 6 inches or strokes under 3/4 inch (1910.37(b)(7)).
4. Dead lamp or dead battery — sign not illuminated to 5 foot-candles at time of inspection (1910.37(b)(6)).
5. No sign at exit — a designated exit door with no EXIT sign at all (1910.37(b)(2)).
6. Misleading door not labeled — a storage room or basement stair near an exit corridor with no "NOT AN EXIT" or use label (1910.37(b)(5)).

The single most effective preventive measure: generate and post an accurate evacuation map showing every exit sign location. Discrepancies between the map and the actual signs surface during your annual map review — before an inspector finds them. See the OSHA evacuation map display requirements for what the posted map itself must show, and the 12-element evacuation map checklist for the complete visual element list.

Frequently asked questions