How this calculator works
Each pipe size is counted on its own, because a tube fits only one size of pipe. For one size, add the extra tube used at the elbows and tees to the run, add your cutting allowance, then divide by the length of one tube and round up to a whole tube.
Worked example: 20 ft of 1/2 in pipe with 4 fittings at 6 in each is 20 + 2.0 = 22.0 ft; with 10% extra that is 24.2 ft, which is 4.03 tubes of 6 ft, so buy 5. A second size is counted the same way and rounded up on its own: 30 ft of 3/4 in pipe with 6 fittings comes to 36.3 ft, so buy 7, and the two sizes together are 12 tubes.
Assumptions and sources
The assumptions behind your numbers (waste, sizes, rates) are listed in the notes directly under your results, and they update when you change an input.
The formula and a worked example are shown above, so you can check any result by hand. Read how we calculate and check our numbers. Results are estimates for planning: supplier products vary, so check the size printed on the label.
Tubes for common runs of one pipe size (6 ft tubes, an elbow or tee every 5 ft, 6 in each, 10% extra)
Whole tubes to buy.
| Pipe | Tubes to buy |
|---|---|
| 6 ft | 2 |
| 10 ft | 3 |
| 20 ft | 5 |
| 30 ft | 7 |
| 40 ft | 9 |
| 60 ft | 13 |
Tips before you buy
- Start with pipes in unheated places: crawl spaces, garages, basement ceilings and outside walls.
- Measure each pipe size separately, since a tube for one size does not fit another.
- Tape or tie the seams and joints; the cut edges at elbows and tees are where gaps open.
- Buy a tube or two more than the count if the package is sold in sets, so a mistake does not stop the job.
Quick answers by size
Tools & materials for this project
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Frequently asked questions
How much pipe insulation do I need?
Measure each pipe size, add a little for each elbow and tee and for cutting, then divide by the length of one tube and round up. For 20 ft of 1/2 in pipe with 4 fittings that is 5 tubes of 6 ft.
Do I need a different tube for each pipe size?
Yes. The tube is sold by the pipe it fits, so count 1/2 in, 3/4 in and 1 in pipe separately and check the size printed on the package.
Should I round up?
Yes. Tubes are sold whole, so the 4.03 tubes worked out for the 1/2 in pipe above means buying 5.
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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.