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PEX Pipe Calculator — How Much PEX Tubing Do I Need?

Estimate the PEX tubing you need for a plumbing project in seconds. Enter one run or build a multi-run takeoff, add a waste allowance, and see the total linear feet and number of coils to buy.

PEX tubing quantity calculator

Inputs stay in your browser.

Units
Run length
Waste / connection allowance
Coil length

PEX tubing to order

132 ft

Measured runs plus waste allowance

Base tubing

120 ft

Waste / allowance

12 ft

10%

Coils / sections

2

Purchased footage

200 ft

Estimated leftover

68 ft

120 ft base + 12 ft allowance = 132 ft to order · 100 ft coils → 2 coils.

Quantity takeoff only. This does not size PEX diameter or check pressure or code.

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How much PEX tubing do I need?

Required tubing is the measured run length plus the waste/connection allowance you choose. If you buy coils, coils = ceil(required tubing ÷ coil length). Measure the actual route — offsets, rises, and manifold legs — not a straight-line room dimension.

How to use the PEX pipe calculator

  1. Enter your run length, or switch to a multi-run takeoff.
  2. Add each plumbing run and quantity if the job has more than one branch.
  3. Choose a waste/connection allowance (5–20%, or a custom percent).
  4. Enter the coil length you plan to buy (100, 300, or 500 ft are common).
  5. Review total linear feet, coils, leftover, and optional cost.

PEX pipe calculator formula

The math below is the same function the calculator runs.

  • Single run: baseFeet = length
  • Multiple runs: baseFeet = sum(length × quantity)
  • Rectangular perimeter: baseFeet = 2 × (length + width)
  • allowanceFeet = baseFeet × (wastePercent ÷ 100)
  • orderFeet = baseFeet + allowanceFeet
  • coils = ceil(orderFeet ÷ coilLength)
  • purchasedFeet = coils × coilLength
  • leftoverFeet = purchasedFeet − orderFeet

PEX tubing examples

Numbers are generated by the same engine as the tool.

  • 50 ft + 10%: 50 ft base · 55 ft to order · 1 coils
  • 120 ft + 10%: 120 ft base · 132 ft to order · 2 coils
  • 200 ft + 10%: 200 ft base · 220 ft to order · 3 coils
  • Multi-run takeoff: 267 ft base · 293.7 ft to order · 3 coils

The takeoff example is 42 ft × 3, 28 ft × 2, and 85 ft × 1. That is 267 ft of base tubing. With 10% waste it is 293.7 ft to order, which is 3 coils of 100 ft.

What does the PEX calculator include?

  • Measured single runs
  • Multiple branch/home-run rows
  • Waste and connection allowance
  • Coil rounding, purchased footage, and leftover
  • Optional material cost if you enter a price

It does not pick PEX diameter. Use the pipe sizing calculator for that. After you know length, the pipe volume calculator can estimate water in the line.

Different ways people search for a PEX calculator

Most people want the same takeoff: how much PEX tubing they need, how many feet of PEX to buy, and how many 100 ft or 300 ft coils that is. A PEX footage calculator, PEX coil calculator, and PEX takeoff calculator are all that quantity question. A PEX tubing length calculator is the same tool with a single measured run. This page is not a diameter or radiant-loop design calculator.

Radiant-floor PEX is a different job

Heated-floor layouts need loop length, spacing, and manifold design. You can still add those loop lengths here as takeoff rows, but this is not a radiant design calculator. A dedicated radiant-floor PEX page can own that intent later without replacing this plumbing-run takeoff.

Common mistakes

  • Measuring a straight-line room dimension instead of the actual pipe route.
  • Forgetting manifold, supply, and return sections on a home-run layout.
  • Buying the exact measured footage with no waste allowance.
  • Using the wrong coil length, so the coil count does not match what the store sells.
  • Treating footage as pipe-size or pressure design.
  • Using perimeter mode for a branched layout that is not a rectangle.

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PEX tubing FAQ

How much PEX tubing do I need?

Measure each plumbing run along the actual route, add your waste allowance, then round up to full coils. 120 ft plus 10% is 132 ft, or two 100 ft coils.

How do you calculate PEX tubing length?

baseFeet is the run, the takeoff sum, or 2 × (length + width) for a rectangle. orderFeet = baseFeet × (1 + wastePercent ÷ 100).

How much extra PEX should I buy?

This planner defaults to 10%. Tight, simple runs may use 5%. Branched work with many fittings often uses 10–15%. There is no single code extra.

How many 100-foot PEX coils do I need?

Divide the order footage by 100 and round up. 132 ft needs 2 coils. 220 ft needs 3 coils.

Does the PEX pipe size change how many feet I need?

Diameter does not change the measured length. A 1/2 in home run and a 3/4 in trunk of the same route need the same footage. Size them with a pipe-sizing tool.

Can I calculate multiple PEX runs?

Yes. Project takeoff adds rows for name, length, and quantity, then sums length × quantity before waste and coils.

Can I calculate a rectangular perimeter?

Yes. Perimeter mode uses 2 × (length + width). Use it only for a rectangular loop, not a typical branched house layout.

Does this calculator size the PEX diameter?

No. It estimates quantity only. Use the pipe sizing calculator for diameter and fixture units.

Can I use this calculator for radiant floor heating?

You can add loop lengths as takeoff rows. It does not space loops, size manifolds, or design a heated floor. That is a separate radiant-floor intent.