Egress Window Compliance Calculator
Determine whether a window meets the International Residential Code (IRC) egress requirements for bedrooms and habitable spaces below the fourth story.
Formulas & IRC R310 Requirements
Net Clear Opening Area:
Area (sq in) = Clear Width (in) × Clear Height (in)
Area (sq ft) = Area (sq in) ÷ 144
All four conditions must be satisfied simultaneously:
- Clear Opening Width ≥ 20 inches
- Clear Opening Height ≥ 24 inches
- Net Clear Opening Area ≥ 5.7 sq ft (820.8 sq in)
- Sill Height Above Finished Floor ≤ 44 inches
Note: "Clear opening" refers to the actual unobstructed opening when the window is fully open, not the rough opening or frame size.
Assumptions & References
- Based on IRC Section R310 (2021 IRC) — Emergency Escape and Rescue Openings.
- Requirements apply to sleeping rooms and basements with habitable space in one- and two-family dwellings.
- Windows on the fourth story or higher above grade plane are exempt from these requirements per IRC R310.1.
- Dimensions entered must represent the net clear opening (fully open position), not the rough opening or sash size.
- Basement window wells deeper than 44 inches require a permanently affixed ladder or steps (IRC R310.2.3.1).
- Some jurisdictions have adopted local amendments — always verify with your local Authority Having Jurisdiction (AHJ).
- Storm windows and security bars must be openable from the inside without a key or special tool (IRC R310.4).
- This calculator does not account for window well sizing, operational hardware, or local code amendments.