How this calculator works
Each door needs a seal along the top and both sides: twice the height plus the width. A window needs a seal all the way round each sash, which is twice the width plus twice the height, and a double hung window needs the middle (the meeting rail) as well, another width. Add the doors and the windows, add an allowance for cutting, and divide by the length of a roll, rounded up. Each door also needs a sweep or a threshold seal for the bottom.
Worked example: two doors of 36 by 80 inches take 32.7 ft, and ten double hung windows of 36 by 48 inches take 170.0 ft. With 10% extra that is 223 ft (203 ft with none), which is 14 rolls of 17 ft, with 2 door sweeps. With casement windows it is 190 ft. Four windows take 111 ft (7 rolls), and a larger house with 3 doors and 20 windows takes 428 ft. In 50 ft rolls the first house takes 5.
Weatherstripping for common houses (double hung windows 36 × 48 in, 2 doors, 10% extra)
Feet to buy, and rolls of 17 ft.
| Windows | Feet to buy | Rolls of 17 ft |
|---|---|---|
| 4 | 111 | 7 |
| 6 | 148 | 9 |
| 8 | 186 | 11 |
| 10 | 223 | 14 |
| 12 | 260 | 16 |
| 16 | 335 | 20 |
| 20 | 410 | 25 |
Tips before you buy
- Check where the drafts are first: hold a stick of incense or a candle near the edges on a windy day.
- Clean the surface with rubbing alcohol before you stick foam on, so that it does not peel.
- Measure the gap, since a thick seal in a thin gap stops the door from closing.
- Fit a sweep to the bottom of each exterior door, or a threshold seal.
- Replace old brittle seals: weatherstripping lasts a few years, not for ever.
Tools & materials for this project
Affiliate links As an Amazon Associate we earn from qualifying purchases. These links do not change what you pay.
Frequently asked questions
How much weatherstripping do I need for a door?
About 16.3 feet for a 36 by 80 inch door: the top and both sides, plus a sweep for the bottom.
How much weatherstripping do I need for a window?
About 17.0 feet for a 36 by 48 inch double hung window, and 14.0 feet for a casement.
How many rolls of weatherstripping do I need for a house?
For two doors and ten double hung windows, 223 ft, which is 14 rolls of 17 ft.
What type of weatherstripping lasts longest?
V-strip (tension seal) and rubber or silicone bulb seals last longer than foam tape, which wears out in a few years.
Does weatherstripping save money?
Yes, as drafts are a large part of the heat loss in many homes, and it costs little. The saving depends on how leaky your windows and doors are.
Add this calculator to your website
Running a blog, a contractor site or a class page? You can put this calculator on it for free. Copy the code below, and please leave the link underneath the calculator in place. The small script just resizes the frame to fit the results; if your site strips scripts, the calculator still works inside a scrolling frame.
Related calculators & guides
Estimates only. Results assume standard materials and simple shapes. Supplier products vary, and the final call on quantity, structure and safety is yours. Check your local code and your supplier's guidance before ordering.