Hot lines: — ft | Cold lines: — ft | Supply runs: — | Sticks: —
Fitting and Support Estimate
| Elbows | — | Tees | — |
| Couplings | — | Crimp / clamp rings | — |
| Supports / straps | — | Total fittings | — |
Shopping List
- PEX tubing—
- Coils / rolls—
- Elbows—
- Tees—
- Couplings—
- Crimp / clamp rings—
- Supports / straps—
- Estimated pipe cost—
Common Fixture Run Distances (worksheet)
| Fixture | Typical run from source | Lines |
|---|---|---|
| Bathroom sink | 10 – 20 ft | Hot + cold |
| Toilet | 10 – 20 ft | Cold only |
| Shower / tub | 12 – 25 ft | Hot + cold |
| Kitchen sink | 15 – 30 ft | Hot + cold |
| Dishwasher | 15 – 30 ft | Hot only |
| Washing machine | 10 – 25 ft | Hot + cold |
| Water heater | varies | Trunk feed |
| Hose bib | 5 – 30 ft | Cold only |
How Much PEX Do I Need?
Total PEX length depends on three things: how far each fixture is from the water source, how many fixtures you are feeding, and whether you run separate hot and cold lines. Start with the average straight-run distance, multiply by the number of supply lines, then add allowances for vertical rises, bends around framing, fittings, and waste. The calculator above does this for you and converts the result into coils or rolls plus an estimated fitting and support count. As a rule of thumb, buy about 10 percent more than the bare calculation to cover mistakes and offcuts.
PEX Manifold vs Trunk-and-Branch
A trunk-and-branch layout runs a large main line through the house with smaller branches teed off to each fixture, much like traditional copper plumbing. It uses less total pipe and fewer manifold ports but needs many tee fittings buried in walls. A manifold (home-run) system places a central distribution block near the water heater and runs a dedicated line to every fixture. It uses more pipe but almost no hidden fittings, gives each fixture steady pressure, and lets you shut off one fixture at a time. Manifolds shine in new construction and slab routing; trunk-and-branch is often cheaper for a straightforward repipe.
PEX Sizing Guide
Pipe size sets the flow each line can carry. Use this as a starting point and confirm against fixture flow requirements.
| Size | Typical use | Approx. flow |
|---|---|---|
| 3/8 in. | Short fixture stub-outs, lavatory faucets | up to ~1.5 GPM |
| 1/2 in. | Most individual fixtures and branches | up to ~5 GPM |
| 3/4 in. | Branch trunks feeding several fixtures | up to ~11 GPM |
| 1 in. | Main trunk lines, whole-house feeds | up to ~18 GPM |
PEX-A vs PEX-B: PEX-A is the most flexible, resists kinks (a heat gun restores a kink), and uses expansion fittings that keep full flow. PEX-B is stiffer and cheaper, uses crimp or clamp rings, and the insert fittings slightly reduce inside diameter. Both are code-approved for potable water; PEX-A is popular for manifold home runs, PEX-B for budget repipes.
Frequently Asked Questions
Do I need separate hot and cold runs? Yes for any fixture using hot water. Toilets and hose bibs are cold only, which the hot/cold setting above accounts for.
How often does PEX need support? Roughly every 32 inches horizontally and at each change of direction; vertical runs need support at each floor.
Coils or sticks? Flexible coils suit long continuous runs and manifolds; rigid sticks are handy for short straight exposed runs.
Can I mix PEX-A and PEX-B? Yes, with the correct transition fittings, though most installers stick to one type and matching fittings.