A PEX tubing size chart provides outside diameter (OD), inside diameter (ID), wall thickness, flow rate, and pressure drop data for cross-linked polyethylene (PEX) pipe commonly used in residential plumbing. PEX has largely replaced copper in new construction due to its flexibility, freeze resistance, and lower cost. Available in 3/8", 1/2", 3/4", and 1" trade sizes for most residential applications.
PEX Tubing Dimensions & Flow Data
| Trade Size | OD (in) | ID PEX-A (in) | ID PEX-B (in) | Flow @ 8 fps (gpm) | Typical Use |
|---|---|---|---|---|---|
| 3/8" | 0.500 | 0.350 | 0.330 | 1.5 | Short runs, single fixtures |
| 1/2" | 0.625 | 0.475 | 0.450 | 3.2 | Fixture supply lines, most common |
| 3/4" | 0.875 | 0.671 | 0.650 | 7.2 | Main distribution lines |
| 1" | 1.125 | 0.890 | 0.860 | 12.4 | Main trunk lines, large homes |
| 1-1/4" | 1.375 | 1.116 | 1.077 | 20.0 | Radiant heating systems |
| 1-1/2" | 1.625 | 1.332 | 1.290 | 28.5 | Commercial / large radiant |
| 2" | 2.125 | 1.749 | 1.700 | 49.0 | Large commercial systems |
PEX-A vs PEX-B vs PEX-C Comparison
| Property | PEX-A | PEX-B | PEX-C |
|---|---|---|---|
| Flexibility | Highest | Moderate | Lowest |
| Cost | Highest | Lowest | Moderate |
| Kink Resistance | Excellent | Good | Fair |
| Shape Memory | Yes (heat-fixable) | No | No |
| Chlorine Resistance | Good | Excellent | Good |
| Availability | Moderate | Widely available | Limited |
| Crosslink Degree | ~75% | ~65% | ~60% |
How to Select the Right PEX Tubing Size
Proper PEX tubing sizing ensures adequate water pressure and flow rate throughout your home's plumbing system. Undersized pipes cause low pressure; oversized pipes waste money and can reduce water temperature maintenance in hot lines.
General Sizing Guidelines
For most residential homes: use 3/4" PEX for the main cold and hot supply trunk lines coming from the water heater and main shutoff. Branch off to individual fixtures using 1/2" PEX for runs up to 50 feet. Use 3/8" PEX only for very short runs (under 6 feet) to a single low-flow fixture.
Manifold (Home-Run) Systems
Many modern homes use a manifold system where each fixture gets a dedicated 1/2" PEX line running directly from a central manifold. This eliminates cross-pipe pressure drops and allows individual fixture shutoff. The manifold itself connects to a 3/4" or 1" supply trunk.
Pressure Drop Considerations
Longer runs lose pressure through friction. For runs over 50 feet, consider upgrading to the next size (e.g., 3/4" instead of 1/2"). The flow rate column in the table above shows capacity at 8 fps — a typical maximum residential velocity to prevent pipe noise.
FAQ
Is this PEX size chart free?
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What is the difference between PEX-A, PEX-B, and PEX-C?
PEX-A (Engel method) is the most flexible and can be repaired with a heat gun using shape memory. PEX-B (Silane method) is the most common and cost-effective, with slightly stiffer walls. PEX-C (electron beam) is the stiffest and least common. For most residential plumbing, PEX-B is the standard choice due to its balance of cost, availability, and performance.
What size PEX should I use for a bathroom?
For most residential applications: use 1/2" PEX for individual fixture supply lines (sinks, toilets, showers) and 3/4" PEX for main distribution lines. 3/8" PEX is used for short runs to a single fixture. Always consult local plumbing codes for your jurisdiction, as requirements vary.
Can PEX be used for hot and cold water lines?
Yes, PEX is suitable for both hot and cold water supply. Red PEX is conventionally used for hot water and blue for cold, but these colors are just for identification — the material itself is the same. PEX is rated for temperatures up to 200°F (93°C) at lower pressures, which exceeds typical residential hot water temperatures.
What is the maximum pressure rating for PEX tubing?
Standard 1/2" PEX-B is rated for 160 psi at 73°F (23°C) and 100 psi at 180°F (82°C). Residential water pressure is typically 40-80 psi, well within this range. Always check the manufacturer's specifications for your specific product and temperature.