Schedule 40 & 80 Pipe Dimensions — NPS Sizes for PVC, CPVC & ABS

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NPS Pipe Dimensions

NPS (Nominal Pipe Size) is the North American standard for pipe sizing. Like NPT threads, the “nominal” size doesn’t match the actual dimensions — it’s a naming convention that’s been around for over a century.

The OD is constant for a given NPS size. The schedule (40, 80, etc.) determines wall thickness — higher schedule = thicker wall = smaller bore = higher pressure rating.

Schedule 40 Dimensions

NPS OD (in) Wall (in) ID (in) Weight (lb/ft) steel
1/8″ 0.405 0.068 0.269 0.24
1/4″ 0.540 0.088 0.364 0.42
3/8″ 0.675 0.091 0.493 0.57
1/2″ 0.840 0.109 0.622 0.85
3/4″ 1.050 0.113 0.824 1.13
1″ 1.315 0.133 1.049 1.68
1-1/4″ 1.660 0.140 1.380 2.27
1-1/2″ 1.900 0.145 1.610 2.72
2″ 2.375 0.154 2.067 3.65
2-1/2″ 2.875 0.203 2.469 5.79
3″ 3.500 0.216 3.068 7.58
4″ 4.500 0.237 4.026 10.79
6″ 6.625 0.280 6.065 18.97
8″ 8.625 0.322 7.981 28.55

Schedule 80 Dimensions

NPS OD (in) Wall (in) ID (in) Weight (lb/ft) steel
1/8″ 0.405 0.095 0.215 0.31
1/4″ 0.540 0.119 0.302 0.54
3/8″ 0.675 0.126 0.423 0.74
1/2″ 0.840 0.147 0.546 1.09
3/4″ 1.050 0.154 0.742 1.47
1″ 1.315 0.179 0.957 2.17
1-1/4″ 1.660 0.191 1.278 3.00
1-1/2″ 1.900 0.200 1.500 3.63
2″ 2.375 0.218 1.939 5.02
3″ 3.500 0.300 2.900 10.25
4″ 4.500 0.337 3.826 14.98
6″ 6.625 0.432 5.761 28.57
8″ 8.625 0.500 7.625 43.39

PVC & CPVC Pipe

PVC and CPVC pipe use the same OD and schedule dimensions as steel pipe — that’s by design so they share fittings. The difference is material properties:

  • PVC Schedule 40: Max 140°F, good chemical resistance, most common for drain/waste/vent and cold water supply
  • CPVC Schedule 80: Max 200°F, suitable for hot water distribution
  • ABS: Same dimensions, used primarily for drain/waste/vent (black pipe)

Key Takeaway

NPS size ≠ actual diameter. A “1-inch pipe” has a 1.315″ OD and a 1.049″ bore (Sch 40). Always look up the actual dimensions.

Related: NPT Thread Dimensions | NPT Tap Drill Sizes