Pipe Schedule Converter
Look up pipe schedule numbers and their wall thickness for standard pipe sizes.
Select nominal pipe size and schedule for dimensions.
Select pipe size and schedule — see wall thickness and inner diameter.
Pipe schedule numbers indicate wall thickness for a given nominal pipe size.
Higher schedule = thicker wall = higher pressure rating.
Common schedules:
- Schedule 5: thin wall (low pressure)
- Schedule 10: light wall
- Schedule 40: standard (most common for plumbing)
- Schedule 80: extra heavy (high pressure, industrial)
- Schedule 160: very heavy (extreme pressure)
Example: 1-inch nominal pipe:
| Schedule | Wall (in) | Wall (mm) | ID (in) |
|---|---|---|---|
| Sch 5 | 0.065 | 1.651 | 1.185 |
| Sch 10 | 0.109 | 2.769 | 1.097 |
| Sch 40 | 0.133 | 3.378 | 1.049 |
| Sch 80 | 0.179 | 4.547 | 0.957 |
| Sch 160 | 0.250 | 6.350 | 0.815 |
Note: “Nominal” pipe size is NOT the actual diameter. The outer diameter (OD) stays the same for all schedules. The inner diameter (ID) decreases as wall thickness increases.
Pipe sizing trips up almost everyone the first time, because “nominal” pipe size is neither the inside nor the outside diameter. It’s a label loosely tied to the old inside diameter of standard-wall pipe, kept for compatibility. What actually stays constant across schedules for a given nominal size is the outside diameter, so fittings thread on regardless of wall thickness.
That fixed OD is the key to schedules. As the schedule number climbs, the wall thickens by eating inward, so the inside diameter shrinks. A Schedule 80 pipe handles much higher pressure than Schedule 40 of the same nominal size, but its narrower bore restricts flow. Engineers pick a schedule by balancing the two: enough wall for the pressure, enough bore for the flow. It’s also why you can’t judge a pipe’s real capacity from its nominal size alone, and why a “1-inch” pipe rarely measures exactly an inch anywhere on it.
How we build and check this converter
This converter runs entirely in your browser, so the numbers you enter stay on your device. The math behind it is written by hand and tested against worked examples and standard references before the page goes live.
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