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Egress Window Compliance Calculator
Check if your window meets IRC Section R310 egress requirements for basement and sleeping room windows. Enter your measurements below — results are instant.
Enter Your Window Measurements
All measurements in inches. Measure the open window at its narrowest point.
IRC R310 Requirements Reference
| Requirement | Basement/Above Grade | Grade Floor (Exterior at Grade) |
|---|---|---|
| Net clear opening area | 5.7 sq ft minimum | 20.4 sq ft minimum |
| Net clear opening height | 24 inches minimum | 24 inches minimum |
| Net clear opening width | 20 inches minimum | 20 inches minimum |
| Sill height from finished floor | 44 inches maximum | 44 inches maximum |
Source: International Residential Code (IRC) Section R310. All 50 states have adopted the IRC in some form; local amendments may vary.
Estimated Frame Deductions by Window Type
These are typical deductions from rough opening to net clear opening. Actual deductions vary by manufacturer — always measure with the window installed and fully open.
| Window Type | Width Deduction | Height Deduction | Opening Fraction |
|---|---|---|---|
| Casement (full crank-out) | ~2.5–3.5" | ~2.5–3.5" | ~90–95% of sash area |
| Double-hung (bottom sash) | ~3–4" | ~4–5" per sash | ~45–50% of window area |
| Single-hung | ~3–4" | ~4–5" | ~45–50% of window area |
| Horizontal slider (half) | ~3–4" per half | ~3–4" | ~45–50% of window area |
| Awning | ~2.5–3.5" | ~2.5–3.5" | ~85–90% of sash area |
Next Steps
Full Egress Guide
Everything about egress requirements, permits, window wells, and inspection.
→Basement Egress Permit
Step-by-step permit process for adding or enlarging a basement egress window.
→How to Measure
Detailed guide to measuring net clear opening correctly, with diagrams.
→Permit Checklist
Free printable checklist for your egress window permit application.
→