How Much Pipe Insulation for 20 Feet of Pipe?

20 ft of pipe takes 5 tubes of 6 ft foam pipe insulation, for one pipe size with 4 elbows and tees. That is 20 ft of run plus 6 in of extra tube at each fitting and 10% for cutting, 24.2 ft in all, rounded up to whole tubes.

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This calculator needs JavaScript. Turn it on to enter your own numbers. The example result on this page is worked out for the typical job shown in the form, and the formula and worked example below let you check it by hand.

Length of 1/2 in pipe

Add up the runs you can reach: basement ceilings, crawl spaces, garages, outside walls.

Elbows and tees on the 1/2 in pipe

fittings

Length of 3/4 in pipe

Leave at 0 if you have no 3/4 in pipe. Each pipe size is counted on its own.

Elbows and tees on the 3/4 in pipe

fittings

Length of 1 in pipe

Elbows and tees on the 1 in pipe

fittings

Extra tube for each elbow or tee

An angled cut at an elbow or a notch at a tee uses a little more tube than the straight run. 6 in is a starting guess: change it to suit your fittings.

Length of one tube (printed on the package)

Read it off the package; every tube of one product is the same length.

Extra for cutting

Cut ends and mistakes.

Results

Example job shown. Change the numbers to match yours.

Tubes to buy in all

5 tubes

Rounded up for each pipe size, tubes of 6 ft

Tubes for each pipe size

For 1/2 in pipeBuy 5 tubes of 6 ft: 5 tubes
For 3/4 in pipeNone needed: 0 tubes
For 1 in pipeNone needed: 0 tubes

Lengths worked out

1/2 in pipe with fittings and extra: 24.2 ft
3/4 in pipe with fittings and extra: 0.0 ft
1 in pipe with fittings and extra: 0.0 ft
Pipe to insulate: 20.0 ft

Each pipe size needs its own tube size, because the hole in the tube has to fit the outside of the pipe. Check the tube size on the package against your pipe, since copper, PEX and iron pipes of the same nominal size have different outside diameters. This tool counts tubes only: it makes no claim about thickness, R-value or how much protection from freezing you get.

Before you buy: round up to whole packs, check the size printed on the label, and add a little spare. Your supplier has the final say.

Blueprint

20 ft · 5 tubes

20 ft of pipe, by tube length

For one pipe size with 4 elbows and tees at 6 in of extra tube each and 10% for cutting, which is 24.2 ft of tube. Read the tube length off your package.

Length of one tube	Tubes to buy
3 ft	9
4 ft	7
6 ft	5
8 ft	4

20 ft of pipe, by number of fittings

6 ft tubes, 6 in of extra tube for each elbow or tee, 10% for cutting.

Elbows and tees	Tube length needed	Tubes to buy
0	22.0 ft	4
4	24.2 ft	5
8	26.4 ft	5

The calculator's own example

20 ft of 1/2 in pipe with 4 fittings is where the pipe insulation calculator opens, so the form above starts on these numbers. The run is 20 ft, the fittings add 4 × 6 in = 2 ft, and 10% for cutting brings it to 24.2 ft.

Divided by a 6 ft tube that is 4.03 tubes, so buy 5. With no allowance for cutting the same run needs 22.0 ft, 4 tubes: the extra 10% is what pushes it up a tube.

For which pipes to insulate first and what to do in a cold snap, see how to keep pipes from freezing.

Want to change anything else? The calculator above is the full Pipe Insulation Calculator: Foam Tubes to Buy: edit any number and the results update instantly.

Tools & materials for this project

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Cable ties Faucet cover

Frequently asked questions

How much pipe insulation do I need for 20 feet of pipe?

24.2 ft of tube, or 5 tubes of 6 ft, for 20 ft of one pipe size with 4 elbows and tees at 6 in each and 10% extra. With no fittings it is 4 tubes.

How many feet of pipe insulation for 20 feet of pipe?

24.2 ft with 4 fittings at 6 in each and 10% extra, which is 5 tubes of 6 ft.

Does 3/4 in pipe need more tubes than 1/2 in?

Not for the same length: 20 ft of either size takes 5 tubes. The tubes are a different size, so you cannot share them between the two.

Related sizes and 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.