Schedule 40 Pipe Sizes & Dimensions
Complete Schedule 40 pipe dimensions reference chart. Outside diameter (OD), inside diameter (ID), wall thickness, and weight per foot for steel and PVC pipe sizes from 1/8" to 24".
Schedule 40 Steel Pipe Dimensions (Imperial)
| NPS | DN | OD (in) | Wall (in) | ID (in) | Weight (lb/ft) |
|---|---|---|---|---|---|
| 1/8" | 6 | 0.405 | 0.068 | 0.269 | 0.24 |
| 1/4" | 8 | 0.540 | 0.088 | 0.364 | 0.42 |
| 3/8" | 10 | 0.675 | 0.091 | 0.493 | 0.57 |
| 1/2" | 15 | 0.840 | 0.109 | 0.622 | 0.85 |
| 3/4" | 20 | 1.050 | 0.113 | 0.824 | 1.13 |
| 1" | 25 | 1.315 | 0.133 | 1.049 | 1.68 |
| 1-1/4" | 32 | 1.660 | 0.140 | 1.380 | 2.27 |
| 1-1/2" | 40 | 1.900 | 0.145 | 1.610 | 2.72 |
| 2" | 50 | 2.375 | 0.154 | 2.067 | 3.65 |
| 2-1/2" | 65 | 2.875 | 0.203 | 2.469 | 5.79 |
| 3" | 80 | 3.500 | 0.216 | 3.068 | 7.58 |
| 3-1/2" | 90 | 4.000 | 0.226 | 3.548 | 9.11 |
| 4" | 100 | 4.500 | 0.237 | 4.026 | 10.79 |
| 5" | 125 | 5.563 | 0.258 | 5.047 | 14.62 |
| 6" | 150 | 6.625 | 0.280 | 6.065 | 18.97 |
| 8" | 200 | 8.625 | 0.322 | 7.981 | 28.55 |
| 10" | 250 | 10.750 | 0.365 | 10.020 | 40.48 |
| 12" | 300 | 12.750 | 0.406 | 11.938 | 53.52 |
| 14" | 350 | 14.000 | 0.437 | 13.126 | 63.30 |
| 16" | 400 | 16.000 | 0.500 | 15.000 | 82.77 |
| 18" | 450 | 18.000 | 0.562 | 16.876 | 104.67 |
| 20" | 500 | 20.000 | 0.593 | 18.814 | 122.91 |
| 24" | 600 | 24.000 | 0.687 | 22.626 | 171.29 |
Source: ANSI/ASME B36.10M (steel), ASTM D1785 (PVC). Weights are approximate. PVC pressure ratings at 73°F (23°C).
Schedule 40 vs Schedule 80 Comparison
| NPS | Schedule 40 | Schedule 80 | ||
|---|---|---|---|---|
| Wall (in) | ID (in) | Wall (in) | ID (in) | |
| 1/2" | 0.109 | 0.622 | 0.147 | 0.546 |
| 3/4" | 0.113 | 0.824 | 0.154 | 0.742 |
| 1" | 0.133 | 1.049 | 0.179 | 0.957 |
| 1-1/2" | 0.145 | 1.61 | 0.2 | 1.5 |
| 2" | 0.154 | 2.067 | 0.218 | 1.939 |
| 3" | 0.216 | 3.068 | 0.3 | 2.9 |
| 4" | 0.237 | 4.026 | 0.337 | 3.826 |
| 6" | 0.28 | 6.065 | 0.432 | 5.761 |
Both schedules share the same OD. Schedule 80 has thicker walls, resulting in a smaller ID and higher pressure rating but reduced flow capacity.
What is Schedule 40 Pipe?
Schedule 40 is the most widely used pipe wall thickness standard in plumbing, HVAC, and general industrial piping. The "schedule" system was introduced by ANSI/ASME B36.10 and defines wall thickness based on the ratio of design pressure to allowable material stress.
Key facts about Schedule 40 pipe:
- Standard: ANSI/ASME B36.10M (steel), ASTM D1785 (PVC)
- Available sizes: 1/8" through 24" NPS (DN 6 through DN 600)
- Materials: Carbon steel, stainless steel, PVC, CPVC, galvanized steel
- Common uses: Water supply, drainage, compressed air, natural gas, fire protection
- OD consistency: The outside diameter is the same across all materials for a given NPS size
NPS vs Actual Dimensions
Nominal Pipe Size (NPS) is a name, not a measurement. A "1-inch" pipe does not have a 1-inch OD or ID. The actual OD of 1" NPS pipe is 1.315 inches. For sizes 14" and above, NPS equals the actual OD.
Schedule 40 PVC Pressure Ratings by Temperature
| Temperature | Derating Factor | 1" Pipe (PSI) | 2" Pipe (PSI) | 4" Pipe (PSI) |
|---|---|---|---|---|
| 73°F (23°C) | 1.00 | 450 | 280 | 220 |
| 80°F (27°C) | 0.88 | 396 | 246 | 194 |
| 100°F (38°C) | 0.75 | 338 | 210 | 165 |
| 120°F (49°C) | 0.62 | 279 | 174 | 136 |
| 140°F (60°C) | 0.50 | 225 | 140 | 110 |
PVC is not rated for use above 140°F (60°C). For hot water applications, use CPVC (rated to 200°F) or copper.
When to Use Schedule 40 vs Other Schedules
Use Schedule 40 for:
- ✓ Residential water supply (up to ~80 PSI)
- ✓ DWV (drain, waste, vent) systems
- ✓ Sprinkler/irrigation systems
- ✓ Low-pressure compressed air
- ✓ Residential natural gas lines
- ✓ General industrial piping under 150 PSI
Use Schedule 80 or higher for:
- ▲ High-pressure water systems (>150 PSI)
- ▲ Chemical processing lines
- ▲ Steam piping
- ▲ Underground where burial loads exist
- ▲ Areas subject to physical damage
- ▲ Threaded PVC connections
Frequently Asked Questions
What does Schedule 40 mean for pipe?
Schedule 40 refers to a standard wall thickness for pipes defined by ANSI/ASME B36.10. The "schedule" number indicates the ratio of internal pressure to allowable stress. Schedule 40 is the most common pipe schedule used in residential and commercial plumbing, water supply, and drainage systems.
What is the OD of 1 inch Schedule 40 pipe?
1-inch Schedule 40 pipe has an outside diameter (OD) of 1.315 inches (33.4 mm). The inside diameter is 1.049 inches (26.6 mm) with a wall thickness of 0.133 inches (3.38 mm). This applies to both steel and PVC Schedule 40 pipe.
What is the pressure rating of Schedule 40 PVC pipe?
Schedule 40 PVC pipe pressure ratings decrease as size increases: 1/2" = 600 PSI, 3/4" = 480 PSI, 1" = 450 PSI, 1-1/2" = 330 PSI, 2" = 280 PSI, 3" = 260 PSI, 4" = 220 PSI, 6" = 180 PSI. These ratings are at 73°F — pressure capacity decreases at higher temperatures.
What is the difference between Schedule 40 and Schedule 80 pipe?
Schedule 80 pipe has thicker walls than Schedule 40, resulting in a smaller inside diameter but the same outside diameter. Schedule 80 handles higher pressures and is more durable but costs more and has slightly reduced flow capacity. For example, 1" Sch 40 has 0.133" wall thickness vs 1" Sch 80 with 0.179" wall thickness.
Is Schedule 40 pipe the same OD for all materials?
Yes. Schedule 40 steel pipe, stainless steel pipe, and PVC pipe all share the same outside diameter (OD) for a given nominal size. This standardization means fittings are interchangeable across materials. The wall thickness and inside diameter can vary slightly, but the OD is consistent across ASTM standards.
What is nominal pipe size (NPS) vs actual dimensions?
Nominal Pipe Size (NPS) is a designation, not an actual measurement. For pipes 1/8" to 12", the NPS does not match the actual OD or ID. For example, a "1-inch" pipe has an actual OD of 1.315 inches. For NPS 14" and above, the NPS equals the actual outside diameter.
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