Calculator Inputs
Example Data Table
These examples show sample planning estimates. Use official JELD-WEN data for final unit selection.
| Window style | Frame size | Estimated clear opening | Area | Upper-floor result |
|---|---|---|---|---|
| Casement | 36 in × 48 in | 29.90 in × 40.89 in | 8.49 sq ft | Pass |
| Double-hung | 36 in × 60 in | 31.75 in × 25.05 in | 5.52 sq ft | Review |
| Slider | 48 in × 48 in | 21.00 in × 44.00 in | 6.42 sq ft | Pass |
| Custom measured | Catalog value | 24.00 in × 34.25 in | 5.71 sq ft | Pass |
Formula Used
Net clear area: (clear width × clear height) ÷ 144. The result is shown in square feet.
Area rule: grade-floor openings use 5.0 square feet when allowed. Other selected openings use 5.7 square feet.
Width and height rules: clear width must be at least 20 inches. Clear height must be at least 24 inches.
Sill rule: sill height must not exceed 44 inches above the finished floor.
Window well area: (well width × well projection) ÷ 144. The target is 9 square feet for below-grade wells.
Optional guides: natural light uses room area × 0.08. Ventilation uses room area × 0.04.
How to Use This Calculator
- Select the opening location. Choose below-grade when a window well is part of the installation.
- Choose measured mode when you have real clear opening data. Use estimate mode for early planning only.
- Enter clear width, clear height, and sill height. Add well details when needed.
- Press the calculate button. Review the result card above the form.
- Download the CSV or PDF report for project records.
Egress Planning Basics
An egress window is more than a replacement size. It is a usable escape opening. It should also support rescue access from outside. This calculator helps you review those points before ordering, quoting, or comparing JELD-WEN style window options.
Why Clear Opening Matters
Frame size is not the same as clear opening. Sashes, balances, hinges, tracks, stops, and screens reduce usable space. A large rough opening can still fail if the active opening is too small. For that reason, the tool lets you enter measured clear width and height. It also includes an estimating mode for early planning.
Code Checks Included
The report checks width, height, net clear area, and sill height. Grade-floor openings can use a lower area target when allowed locally. Upper-floor and many basement openings normally need the larger target. Below-grade choices also need a safe window well. The well must be wide enough, project far enough, and stay usable when the sash opens.
Using the Results
A pass result means the numbers meet the selected rule set. It does not replace local approval. A fail result shows the shortage. You can compare added width, added height, or a different window style. Casement designs often create more clear opening from a smaller frame. Double-hung and slider styles may need larger units.
Practical Measuring Tips
Measure the open space after the sash is fully opened. Do not measure glass size only. Do not include removable sash tricks unless your local official allows them. Measure sill height from the finished floor to the bottom of the clear opening. For wells, measure inside width and projection. Check ladders, covers, grates, and drainage.
Final Review
Use this page as a screening tool. Save the CSV report for records. Print the PDF for customers, inspectors, or installers. Always compare the result with the official product specifications and your local building department before purchase.
Design Notes
Different product lines can use different hardware. Actual JELD-WEN clear opening values may vary by series, size, grille choice, and hinge package. Treat estimated mode as a planning guide only. Choose measured mode when you have catalog data, shop drawings, or an installed unit.
FAQs
What is a net clear opening?
It is the usable open space after the sash is fully opened. It is not the full frame, rough opening, or glass size.
Can I use frame size for final approval?
No. Frame size is only a planning input. Final checks should use measured clear opening data or official product specifications.
Why does grade-floor area differ?
Some rule sets allow 5.0 square feet for grade-floor openings. Local rules can differ, so confirm before ordering.
Does this choose a real JELD-WEN model?
No. It screens dimensions and reports gaps. Use JELD-WEN catalogs, dealer data, and local review for model selection.
When is a ladder required?
This calculator flags a ladder or steps when a below-grade well depth exceeds 44 inches. Confirm the final detail locally.
Can a window well cover fail the report?
Yes. If a cover or grate is present, it should release from inside without keys, tools, or special knowledge.
Why include light and ventilation checks?
They are useful planning guides for bedrooms and living spaces. They do not replace the main emergency opening checks.
Is this calculator legal advice?
No. It is a planning tool. Always verify the result with your building department, inspector, and product documentation.