Bedroom Egress Window Checker
Does your bedroom or basement window meet the escape-opening rules? Enter the clear opening (or estimate it from the window size) and get pass/fail on every requirement.
How this egress window checker works
Every bedroom (and every basement or habitable attic) needs at least one emergency escape and rescue opening, so you can climb out and a firefighter can climb in with gear. The 2021 and 2024 International Residential Code (section R310) sets these limits, and this tool checks each one:
| Requirement | Minimum / maximum |
|---|
| Net clear opening area (upper floors) | 5.7 sq ft |
| Net clear opening area (grade floor or below grade: sill within 44 in of the adjacent ground) | 5.0 sq ft |
| Net clear opening height | 24 in minimum |
| Net clear opening width | 20 in minimum |
| Sill height above finished floor | 44 in maximum |
| Window well area | 9 sq ft minimum, at least 36 in in each direction |
| Window well ladder or steps | Required if the well is deeper than 44 in |
Net clear opening is the open space you can actually pass through with the window fully open, not the size of the glass or the rough opening. The 24 in height and 20 in width are separate minimums. You must meet both and still reach 5.7 (or 5.0) sq ft.
Estimate mode uses simple rules of thumb: casement = unit width and height minus about 3 in each; double-hung or single-hung = width minus 4 in, half the height minus 2 in; slider = half the width minus 2 in, height minus 4 in; awning = width minus 3 in, about half the height. These are approximations only. Check the manufacturer's spec sheet or look for an egress rating on the label.
The opening must also open from the inside without keys, tools or special effort. The IRC is a model code, and many cities and states amend it. Older homes may be held to the code in effect when they were permitted. Always confirm with your local building department.
If your window fails
- Switch to a casement window. The whole sash swings open, so it gives the largest clear opening for its size.
- Order a taller or wider unit. Adding height usually helps more than width.
- Lower the sill if it is higher than 44 in. This is a structural change (new framing and header), so involve a pro.
- For basements, enlarge the window well or add a ladder. The target is at least 9 sq ft and 36 × 36 in.
- A door to the outside (such as a walkout) can serve as the escape opening instead.
Sources
Estimates only — not engineering, legal or code advice. Check requirements with your local building department and a licensed professional before you build.
Common questions
What size does a bedroom egress window have to be?
Under the International Residential Code (R310), the net clear opening must be at least 5.7 square feet, at least 24 inches high and at least 20 inches wide. Those two minimums do not multiply to 5.7 sq ft, so the opening must be larger than 24 × 20 in. The sill can be no more than 44 inches above the finished floor.
Is 5.0 square feet ever allowed for egress?
Yes. The IRC allows a 5.0 sq ft net clear opening for grade-floor or below-grade openings. The code defines a grade-floor opening as one whose sill is not more than 44 inches above or below the finished ground level next to the opening, which covers most ground-floor and basement windows. Upper-story bedrooms need 5.7 sq ft. Your city may amend this, so confirm locally.
How do I measure net clear opening?
Open the window all the way and measure the unobstructed opening: width between the frame and sash edges, and height from the sill to the bottom of the sash. Multiply width × height in inches and divide by 144. Do not use the glass size or the rough opening, because sashes and frames take up space.
Does a double-hung window work as an egress window?
Rarely at standard sizes. Only half the height opens, so a double-hung needs to be very tall, roughly 5 feet or more, to reach 24 in clear height and 5.7 sq ft. Casement and large slider windows are the usual egress choices.
What are the window well requirements for a basement egress window?
The IRC requires a well with at least 9 square feet of floor area and at least 36 inches in both horizontal projection and width. If the well is deeper than 44 inches, it needs a permanently attached ladder or steps usable with the window fully open. The code spec for a ladder is rungs at least 12 in wide, projecting at least 3 in from the wall, spaced no more than 18 in apart vertically. The well must allow the window to open fully.
Do window bars or screens matter?
Yes. Escape openings must be operable from the inside without keys, tools or special knowledge. Bars, grilles or covers are allowed only if they can be released from the inside the same way.