Dimension selector
Interactive Pipe Size and Schedule Lookup
Choose a nominal size and schedule to see standardized OD, nominal wall, calculated bore, internal area, and wall-to-OD ratio.
- Outside diameter
- 2.375 inSource-controlled nominal dimension
- Wall thickness
- 0.154 inSource-controlled nominal dimension
- Inside diameter
- 2.067 inCalculated as OD − 2t
- Internal flow area
- 3.356 in²Calculated as πID² ÷ 4
- Wall / OD ratio
- 6.48%Nominal wall thickness ÷ OD
- Same-size schedule effect
- Schedule 80: 12.0% less bore areaCompared with the other listed schedule at the same NPS
Identify pipe from a field measurement
Use a measured outside diameter or circumference to find the closest listed NPS. Optionally add wall thickness or inside diameter to identify the closest Schedule 40/80 dimensional match.
Enter a positive outside diameter or circumference.
Schedule is not a pressure rating
Schedule identifies a dimensional wall series. Allowable pressure also depends on material specification, temperature, manufacturing tolerance, corrosion allowance, joining method, the applicable piping code, and project conditions.
Server-rendered reference
Pipe Size and Schedule Dimensions
46 common steel-pipe size and schedule combinations from NPS 1/8 through 24.
Search NPS or DN, filter by schedule, select up to four rows for comparison, or choose View to send a row to the diagram.
No pipe sizes match the current filters.
Scroll horizontally to view additional columns and vertically to view more rows. Column headers remain visible while scrolling.
| Compare | Pipe dimensions (in) | (in²) | Action | |||||
|---|---|---|---|---|---|---|---|---|
| NPS 1/8 | DN 6 | Schedule 40 | 0.405 in | 0.068 in | 0.269 in | 0.057 in² | ||
| NPS 1/8 | DN 6 | Schedule 80 | 0.405 in | 0.095 in | 0.215 in | 0.036 in² | ||
| NPS 1/4 | DN 8 | Schedule 40 | 0.540 in | 0.088 in | 0.364 in | 0.104 in² | ||
| NPS 1/4 | DN 8 | Schedule 80 | 0.540 in | 0.119 in | 0.302 in | 0.072 in² | ||
| NPS 3/8 | DN 10 | Schedule 40 | 0.675 in | 0.091 in | 0.493 in | 0.191 in² | ||
| NPS 3/8 | DN 10 | Schedule 80 | 0.675 in | 0.126 in | 0.423 in | 0.141 in² | ||
| NPS 1/2 | DN 15 | Schedule 40 | 0.840 in | 0.109 in | 0.622 in | 0.304 in² | ||
| NPS 1/2 | DN 15 | Schedule 80 | 0.840 in | 0.147 in | 0.546 in | 0.234 in² | ||
| NPS 3/4 | DN 20 | Schedule 40 | 1.050 in | 0.113 in | 0.824 in | 0.533 in² | ||
| NPS 3/4 | DN 20 | Schedule 80 | 1.050 in | 0.154 in | 0.742 in | 0.432 in² | ||
| NPS 1 | DN 25 | Schedule 40 | 1.315 in | 0.133 in | 1.049 in | 0.864 in² | ||
| NPS 1 | DN 25 | Schedule 80 | 1.315 in | 0.179 in | 0.957 in | 0.719 in² | ||
| NPS 1-1/4 | DN 32 | Schedule 40 | 1.660 in | 0.140 in | 1.380 in | 1.496 in² | ||
| NPS 1-1/4 | DN 32 | Schedule 80 | 1.660 in | 0.191 in | 1.278 in | 1.283 in² | ||
| NPS 1-1/2 | DN 40 | Schedule 40 | 1.900 in | 0.145 in | 1.610 in | 2.036 in² | ||
| NPS 1-1/2 | DN 40 | Schedule 80 | 1.900 in | 0.200 in | 1.500 in | 1.767 in² | ||
| NPS 2 | DN 50 | Schedule 40 | 2.375 in | 0.154 in | 2.067 in | 3.356 in² | ||
| NPS 2 | DN 50 | Schedule 80 | 2.375 in | 0.218 in | 1.939 in | 2.953 in² | ||
| NPS 2-1/2 | DN 65 | Schedule 40 | 2.875 in | 0.203 in | 2.469 in | 4.788 in² | ||
| NPS 2-1/2 | DN 65 | Schedule 80 | 2.875 in | 0.276 in | 2.323 in | 4.238 in² | ||
| NPS 3 | DN 80 | Schedule 40 | 3.500 in | 0.216 in | 3.068 in | 7.393 in² | ||
| NPS 3 | DN 80 | Schedule 80 | 3.500 in | 0.300 in | 2.900 in | 6.605 in² | ||
| NPS 3-1/2 | DN 90 | Schedule 40 | 4.000 in | 0.226 in | 3.548 in | 9.887 in² | ||
| NPS 3-1/2 | DN 90 | Schedule 80 | 4.000 in | 0.318 in | 3.364 in | 8.888 in² | ||
| NPS 4 | DN 100 | Schedule 40 | 4.500 in | 0.237 in | 4.026 in | 12.730 in² | ||
| NPS 4 | DN 100 | Schedule 80 | 4.500 in | 0.337 in | 3.826 in | 11.497 in² | ||
| NPS 5 | DN 125 | Schedule 40 | 5.563 in | 0.258 in | 5.047 in | 20.006 in² | ||
| NPS 5 | DN 125 | Schedule 80 | 5.563 in | 0.375 in | 4.813 in | 18.194 in² | ||
| NPS 6 | DN 150 | Schedule 40 | 6.625 in | 0.280 in | 6.065 in | 28.890 in² | ||
| NPS 6 | DN 150 | Schedule 80 | 6.625 in | 0.432 in | 5.761 in | 26.067 in² | ||
| NPS 8 | DN 200 | Schedule 40 | 8.625 in | 0.322 in | 7.981 in | 50.027 in² | ||
| NPS 8 | DN 200 | Schedule 80 | 8.625 in | 0.500 in | 7.625 in | 45.664 in² | ||
| NPS 10 | DN 250 | Schedule 40 | 10.750 in | 0.365 in | 10.020 in | 78.854 in² | ||
| NPS 10 | DN 250 | Schedule 80 | 10.750 in | 0.594 in | 9.562 in | 71.810 in² | ||
| NPS 12 | DN 300 | Schedule 40 | 12.750 in | 0.406 in | 11.938 in | 111.932 in² | ||
| NPS 12 | DN 300 | Schedule 80 | 12.750 in | 0.688 in | 11.374 in | 101.605 in² | ||
| NPS 14 | DN 350 | Schedule 40 | 14.000 in | 0.438 in | 13.124 in | 135.276 in² | ||
| NPS 14 | DN 350 | Schedule 80 | 14.000 in | 0.750 in | 12.500 in | 122.718 in² | ||
| NPS 16 | DN 400 | Schedule 40 | 16.000 in | 0.500 in | 15.000 in | 176.715 in² | ||
| NPS 16 | DN 400 | Schedule 80 | 16.000 in | 0.844 in | 14.312 in | 160.876 in² | ||
| NPS 18 | DN 450 | Schedule 40 | 18.000 in | 0.562 in | 16.876 in | 223.681 in² | ||
| NPS 18 | DN 450 | Schedule 80 | 18.000 in | 0.938 in | 16.124 in | 204.190 in² | ||
| NPS 20 | DN 500 | Schedule 40 | 20.000 in | 0.594 in | 18.812 in | 277.946 in² | ||
| NPS 20 | DN 500 | Schedule 80 | 20.000 in | 1.031 in | 17.938 in | 252.719 in² | ||
| NPS 24 | DN 600 | Schedule 40 | 24.000 in | 0.688 in | 22.624 in | 402.002 in² | ||
| NPS 24 | DN 600 | Schedule 80 | 24.000 in | 1.219 in | 21.562 in | 365.147 in² | ||
Data scope: common wrought-steel NPS sizes from 1/8 through 24 where Schedule 40 and Schedule 80 dimensions are tabulated in this limited reference. Other B36.10 schedules, stainless S schedules, PVC, copper tube, HDPE, ductile iron, tolerances, pressure ratings, and product availability are outside this table.
Table actions and selection controls
Bulk CSV download is intentionally unavailable because the controlling ASME dimensional table is copyrighted. Copy only the limited row needed and verify it against the official standard or approved project documentation.
Selected-row comparison
Compare Pipe Dimensions by Size and Schedule
The default compares Schedule 40 and 80 at NPS 2. Select up to four table rows.
Select pipe rows in the table to compare dimensions.
How to Read a Pipe Size Chart
NPS and DN are nominal designations, not measured diameters. For a given NPS, the outside diameter stays fixed while schedule changes nominal wall thickness and therefore the calculated inside diameter.
- NPS
- Nominal Pipe Size, a standardized size designation for pipe and matching components.
- DN
- Diameter Nominal, a nominal metric designation—not an exact millimeter measurement.
- OD
- Standardized nominal outside diameter used for fit-up, supports, and clearances.
- ID
- Calculated bore from OD minus twice the nominal wall thickness.
Key takeaways
What the Dimensions Mean
- NPS is a designation: NPS 2 steel pipe has a 2.375-inch nominal outside diameter in this system.
- OD stays fixed by NPS: Schedule 80 increases wall thickness inward and reduces ID compared with Schedule 40.
- Use ID for bore geometry: Flow area, velocity, capacity, and friction calculations depend on inside diameter—not the nominal label.
- Keep dimensional systems separate: Steel NPS, stainless S schedules, PVC schedules, copper tube types, and HDPE SDR are not interchangeable.
Important Pipe Size Chart Limitations
Do not use this chart as a pressure rating
The displayed OD and wall values are nominal dimensional references for a limited set of common steel-pipe sizes. They do not establish allowable pressure, corrosion allowance, mill tolerance, material grade, product availability, code compliance, or fitness for a particular service.
Calculated ID and area exclude wall-thickness tolerance, lining, deposits, corrosion, coatings, and out-of-roundness. Use approved manufacturer data and the governing project specification when minimum bore or fit is critical.
Important designation difference
Schedule 40 vs STD and Schedule 80 vs XS
STD (standard weight) and XS/XH (extra strong) are legacy wall designations that coincide with some schedule dimensions only over part of the NPS range. They should not be treated as universal synonyms for Schedule 40 and Schedule 80.
Schedule 40 and STD diverge
At NPS 12, Schedule 40 wall is 0.406 in, while STD wall is 0.375 in. Always check the exact designation instead of assuming they are equivalent.
Schedule 80 and XS diverge
At NPS 12, Schedule 80 wall is 0.688 in, while XS/XH wall is 0.500 in. The designation materially changes the resulting ID and bore area.
How Pipe ID and Flow Area Are Calculated
- Select the NPS or associated DN designation.
- Select Schedule 40 or 80 to obtain nominal wall thickness.
- Calculate nominal inside diameter from ID = OD − 2t.
- Calculate circular bore area from A = πID² ÷ 4.
- Verify tolerances, material, service, and code requirements before design use.
Why Schedule Changes Flow Area
At one NPS, Schedule 40 and Schedule 80 share the same OD in this table. The thicker Schedule 80 wall moves inward, reducing ID. Because area varies with the square of ID, a modest bore reduction creates a larger percentage decrease in flow area.
Field Measurement Lookup
If direct OD is difficult to measure, wrap a tape around the pipe and use circumference: OD = circumference ÷ π. OD can identify the closest listed NPS candidate, but it generally cannot identify schedule because schedules for the same NPS share OD. Add a measured wall thickness or ID to compare against the listed Schedule 40/80 geometry. Coatings, corrosion, ovality, manufacturing tolerance, lining, deposits, and measurement technique can shift a field reading.
Worked dimensional examples
Pipe Size Chart Examples
NPS 2 Schedule 40 ID
Given: OD = 2.375 in and t = 0.154 in.
Method: ID = 2.375 − 2(0.154) = 2.067 in.
Result: Nominal internal area is about 3.356 in².
Check: Confirm tolerances and the project specification when minimum bore matters.
NPS 2 Schedule 40 vs. 80
Given: Both use 2.375 in OD; wall is 0.154 in versus 0.218 in.
Result: ID falls from 2.067 in to 1.939 in, and nominal area decreases by about 12.0%.
Interpretation: At equal volumetric flow, the smaller bore produces higher average velocity before friction and fittings are evaluated.
Scope and error prevention
Selection Guidance and Common Mistakes
Use this chart for
- Common steel NPS and DN lookup
- Schedule 40/80 dimensional comparison
- Preliminary clearances and bore geometry
Verify separately
- Material grade and temperature
- Pressure design and corrosion allowance
- Wall tolerance and manufacturer availability
Do not mix with
- PVC or CPVC schedule tables
- Copper Types K, L, M, or DWV
- HDPE SDR or tubing OD systems
Common mistakes
- Treating NPS as the actual ID or OD.
- Converting NPS directly to millimeters instead of using its associated DN designation.
- Assuming one schedule has the same wall thickness at every NPS.
- Using OD to calculate internal fluid capacity.
- Treating Schedule 80 as a complete pressure rating.
Pipe Size Chart Sources, Scope, and Data Rights
Common wrought-steel NPS dimensions · Schedules 40 and 80 · Dataset version 2.0
This page publishes a limited educational dimensional subset focused on common NPS sizes with Schedule 40 and 80 values plus original derived calculations. It does not reproduce the complete ASME B36.10 table, other schedules, or a bulk standards-derived download.
- ASME B36.10-2022 — Welded and Seamless Wrought Steel PipeOfficial standard front matter and table-of-contents evidence identifying Table 2-1 as the dimensions-and-weights table; the complete standard is rights-controlled.
- ISO 6708:1995 — Pipework Components, Definition and Selection of DNOfficial definition basis for DN as a nominal size designation used for pipework components.
- American Piping Products — Pipe Dimension ChartPublished distributor chart used as an independent cross-check of the limited common-size OD and wall values.
Dataset and Source-Check Details
- Primary standard basis
- ASME B36.10-2022, Table 2-1 scope
- Displayed scope
- NPS 1/8–24; Schedules 40 and 80
- Source-controlled fields
- NPS, DN, nominal OD, nominal wall
- Calculated fields
- Nominal ID and circular bore area
- Known exclusions
- Other schedules, S schedules, tolerances, pressure ratings, grades, and non-steel systems
- Rights status
- Limited educational excerpt; no complete ASME table or bulk CSV
- Rounding
- Inch dimensions to 0.001 in; metric to 0.01 mm; areas to 0.001 in² or 0.1 mm²
- Publisher
- Turn2Engineering
Pipe Size Chart FAQs
No. NPS is a nominal designation. Actual nominal ID changes with wall thickness, so Schedule 80 has a smaller calculated ID than Schedule 40 at the same NPS.
Not for the common steel rows shown here. OD remains fixed for a given NPS while schedule changes wall thickness and therefore ID.
Subtract twice the nominal wall thickness from nominal OD: ID = OD − 2t. The result excludes manufacturing tolerance, corrosion, lining, and deposits.
No. They are associated nominal designation systems. DN should not be treated as the measured diameter in millimeters.
No. Schedule describes nominal wall dimensions. Allowable pressure also depends on material, temperature, code equations, tolerances, corrosion allowance, and joining details.
NPS 2 wrought-steel pipe in this system has a standardized nominal outside diameter of 2.375 inches (60.33 mm). Schedule changes wall thickness and ID, not OD.
Measure circumference around the pipe and divide by π to estimate OD, then compare that OD with standardized NPS outside diameters. The field-measurement lookup above performs this conversion automatically.
No. The designations coincide for many smaller sizes but diverge at larger NPS. For example, at NPS 12 Schedule 40 wall is 0.406 in while STD wall is 0.375 in.
No. At NPS 12, for example, Schedule 80 wall is 0.688 in while XS/XH wall is 0.500 in. Always verify the exact wall designation.
Pipe Size Chart Summary
Use the selector to connect an NPS or DN designation to a common Schedule 40 or 80 steel-pipe cross-section. Read nominal OD and wall thickness, then use the clearly labeled calculated ID and flow area for preliminary geometric checks.
For final design, verify the complete current standard, material specification, manufacturing tolerance, applicable piping code, project conditions, and approved product data.