Egress Window Calculator
Estimate IRC egress opening size and sill height
Floor area of the bedroom or basement room
Where the egress window will be installed
Min Clear Width
—
in
Max Sill Height
—
in
Min Opening Area
—
sq ft
Floor Level
—
level
Disclaimer: Results are estimates based on standard formulas. Not a substitute for professional advice from a licensed contractor, engineer, or architect. Verify all calculations before making purchasing or construction decisions.
How to Use This Calculator
Building or finishing a bedroom? Code requires a code-compliant egress window for emergency escape. Our calculator gives you the minimum opening area, clear width, and sill height per the IRC.
- Enter the room's floor area
- Select whether the room is in a basement or on the first floor
- Run the calculator
- Choose a window that meets or exceeds all three minimums
Expert Insights
Smart analysis for your Egress Window project
Code Minimum Awareness
Basements allow 5.0 sq ft; above-grade rooms need 5.7 sq ft. AI applies the correct minimum for your floor level.
Sill Height & Clear Width
Sill can sit no higher than 44" off the floor, and clear opening width must be at least 20". AI verifies both limits alongside area.
Operation & Access
The window must open from the inside without keys or tools. AI reminds you to test hardware and clear the opening path of furniture.
Calculation Formula
Min opening area = (Basement) ? 5.0 sq ft : 5.7 sq ft
Min clear width = 20 in
Max sill height = 44 in above finished floor
Egress Window Type Comparison
| Window Style | Typical Clear Opening | Meets Egress? | Operation | Best For |
|---|---|---|---|---|
| Casement | Full sash swings out | Yes (easiest) | Crank handle | Small openings, basements |
| Slider (Horizontal) | Half of unit | Often (sized right) | Side sliding | Wider wall space |
| Single/Double Hung | Half of unit, vertical | Needs large size | Vertical slide | Traditional look |
| Awning (with egress hardware) | Hinged at top | Sometimes | Crank handle | Limited — check size |
Authority References
Our calculations are based on guidelines and standards from these authoritative sources:
- International Residential Code (IRC) — Section R310 — Emergency Escape & Rescue Openings. Learn more
- National Fenestration Rating Council (NFRC) — Window Energy & Egress Ratings. Learn more
- U.S. Fire Administration (USFA) — Home Escape & Egress Guidance. Learn more
Frequently Asked Questions
What is the minimum egress window opening size?
The IRC requires a minimum clear opening of 5.7 square feet for above-grade bedrooms and 5.0 square feet for basement egress windows. The clear width must be at least 20 inches.
What is the maximum sill height for an egress window?
The maximum sill height is 44 inches above the finished floor. The window must also open fully from the inside without tools or keys.
Do all bedrooms need egress windows?
Yes. Every IRC-compliant bedroom must have at least one egress window or door that meets the minimum opening size, clear width, and sill height requirements for emergency escape.