Amardeep Steel Centre LLP is an ISO 9001:2015-certified manufacturer, stockist and exporter of seamless and welded steel pipes and tubes across 15+ metallurgies. This page is a complete, buyer-ready nominal pipe size chart and steel pipe dimensions chart covering outside diameter (OD), wall thickness, inside diameter (ID) and schedule, in both millimetres and inches, per ASME B36.10M (carbon & alloy steel pipe) and ASME B36.19M (stainless steel pipe). Use it to size, specify and order pipe for refinery, petrochemical, power, marine and process-industry projects then request a
mill-certified quote directly from our engineering team.
What Is Nominal Pipe Size (NPS) and Nominal Diameter (DN)?
Nominal Pipe Size (NPS) is the North American designation used to describe pipe diameter. It is a dimensionless reference number, not the actual outside or inside diameter of the pipe. Nominal Diameter (DN), used in metric/ISO markets, works the same way and is expressed in millimetres. Neither NPS nor DN is a physical measurement in itself; both are standardized labels that let a pipe, fitting, flange or valve of the same nominal size be interconnected, regardless of manufacturer.
For pipe sizes from NPS 1/8" up to NPS 12", the outside diameter is fixed and does not equal the nominal size — this is a legacy of the earliest pipe standards. From NPS 14" and above, NPS and the actual outside diameter in inches are the same number (e.g., NPS 14" = 14.000" OD).
Pipe Dimension Tables
NPS to DN Conversion Table
|
NPS (inch) |
DN (mm) |
|---|---|
|
1/8" |
DN 6 |
|
1/4" |
DN 8 |
|
3/8" |
DN 10 |
|
1/2" |
DN 15 |
|
3/4" |
DN 20 |
|
1" |
DN 25 |
|
1-1/4" |
DN 32 |
|
1-1/2" |
DN 40 |
|
2" |
DN 50 |
|
2-1/2" |
DN 65 |
|
3" |
DN 80 |
|
4" |
DN 100 |
|
6" |
DN 150 |
|
8" |
DN 200 |
|
10" |
DN 250 |
|
12" |
DN 300 |
For sizes DN 100 (NPS 4") and above, the rule of thumb is: DN ≈ NPS × 25. Above NPS 14", DN equals NPS × 25.4 (i.e., NPS in inches converted directly to mm).
Pipe Dimension Standards: ASME B36.10M vs ASME B36.19M
|
Parameter |
ASME B36.10M |
ASME B36.19M |
|---|---|---|
|
Scope |
Carbon steel & alloy steel pipe (welded and seamless) |
Stainless steel pipe (welded and seamless) |
|
Schedule designation |
5, 10, 20, 30, 40, STD, 60, 80, XS, 100, 120, 140, 160, XXS |
5S, 10S, 40S, 80S (the "S" suffix denotes stainless-specific wall thickness) |
|
Typical use |
Line pipe, structural piping, boiler/process piping (API 5L, ASTM A106, A53, A333) |
Corrosion-resistant process piping (ASTM A312, A358, A778) |
|
Relationship to B36.10M |
Base standard |
Aligned with B36.10M except NPS 14"–22" use Sch 10S; NPS 12" adds Sch 40S; NPS 10"/12" add Sch 80S |
Steel Pipe Dimensions Chart (mm & Inch) — Schedule 40 & Schedule 80
The table below gives OD, wall thickness and ID for the two most commonly ordered schedules, in millimetres and inches, per ASME B36.10M/B36.19M. Need a size or schedule not shown here — 5, 10, 20, 30, 60, 100, 120, 140, 160 or XXS? Browse the full charts on our individual schedule pages, or request a custom cut list.
|
NPS |
OD (mm) |
OD (in) |
Sch 40 / STD Wall (mm) |
Sch 40 ID (mm) |
Sch 80 / XS Wall (mm) |
Sch 80 ID (mm) |
|---|---|---|---|---|---|---|
|
1/2" |
21.3 |
0.840 |
2.77 |
15.8 |
3.73 |
13.9 |
|
3/4" |
26.7 |
1.050 |
2.87 |
20.9 |
3.91 |
18.8 |
|
1" |
33.4 |
1.315 |
3.38 |
26.6 |
4.55 |
24.3 |
|
1-1/4" |
42.2 |
1.660 |
3.56 |
35.1 |
4.85 |
32.5 |
|
1-1/2" |
48.3 |
1.900 |
3.68 |
40.9 |
5.08 |
38.1 |
|
2" |
60.3 |
2.375 |
3.91 |
52.5 |
5.54 |
49.2 |
|
2-1/2" |
73.0 |
2.875 |
5.16 |
62.7 |
7.01 |
59.0 |
|
3" |
88.9 |
3.500 |
5.49 |
77.9 |
7.62 |
73.7 |
|
4" |
114.3 |
4.500 |
6.02 |
102.3 |
8.56 |
97.2 |
|
6" |
168.3 |
6.625 |
7.11 |
154.1 |
10.97 |
146.3 |
|
8" |
219.1 |
8.625 |
8.18 |
202.7 |
12.70 |
193.7 |
|
10" |
273.1 |
10.750 |
9.27 |
254.5 |
15.09 |
242.9 |
|
12" |
323.9 |
12.750 |
9.53 |
304.8 |
17.48 |
289.0 |
Full chart NPS 14"–48": download the complete PDF or request a quote for your exact size.
Stainless Steel Pipe Schedule Chart (5S / 10S / 40S / 80S)
Stainless steel pipe (ASTM A312, A358, A778) follows ASME B36.19M, using "S" schedules that are generally thinner than their carbon-steel equivalents of the same number. Common reference sizes:
|
NPS |
OD (mm) |
Sch 10S Wall (mm) |
Sch 40S Wall (mm) |
Sch 80S Wall (mm) |
|---|---|---|---|---|
|
1/2" |
21.3 |
2.11 |
2.77 |
3.73 |
|
1" |
33.4 |
2.77 |
3.38 |
4.55 |
|
2" |
60.3 |
2.77 |
3.91 |
5.54 |
|
4" |
114.3 |
3.05 |
6.02 |
8.56 |
|
6" |
168.3 |
3.40 |
7.11 |
10.97 |
|
8" |
219.1 |
3.76 |
8.18 |
12.70 |
|
12" |
323.9 |
4.57 |
9.53 |
17.48 |
Explore our full stainless steel seamless & welded pipe range (grades 304/304L/304H, 316/316L/316H, 321, 347, 310S, 904L and duplex) or read our complete guide to stainless steel tubing.
Understanding Pipe Dimensions: OD, Wall Thickness & Length
A complete pipe dimension specification always has three elements:
- Outside Diameter (OD): fixed by NPS/DN for a given size, identical across all schedules of that size.
- Wall Thickness (WT): varies by Schedule (5, 10, 20, 30, 40, STD, 60, 80, XS, 100, 120, 140, 160, XXS); a higher schedule number means a thicker wall and higher pressure rating.
- Length: typically supplied as Single Random Length (SRL, 5–7 m) or Double Random Length (DRL, 11–13 m / 38–40 ft), or cut-to-length on request.
Inside Diameter (ID) is a derived value: ID = OD − (2 × Wall Thickness). Together, OD, WT and material grade determine the pipe's weight per metre and maximum allowable working pressure.
Dimensional tolerances also differ by manufacturing route, see our comparison of seamless vs. welded pipe for how ERW, LSAW, SAW and seamless processes affect OD/WT tolerance bands.
What Is Pipe Schedule?
Pipe "Schedule" (abbreviated Sch.) is the standardized system for specifying pipe wall thickness. Because the pipe primarily carries pressurized fluids, wall thickness must be matched to the design pressure and the allowable stress of the material at design temperature. The governing relationship is:
Sch. = P ÷ [σ]t × 1,000 — where P = design pressure (MPa), [σ]t = allowable material stress at design temperature (MPa)
A higher schedule number always means a thicker wall and a lower inside diameter for the same NPS/DN. Before the schedule system, pipe wall thickness was described using three legacy weight classes, which are still referenced today:
- STD (Standard) — the original base-thickness pipe.
- XS (Extra Strong) — thicker wall for higher-pressure service.
- XXS (Double Extra Strong) — thickest wall in the legacy series, for the most severe pressure duty.
How to Calculate Steel Pipe Weight
Once OD and wall thickness are known, theoretical pipe weight per metre can be calculated as:
W (kg/m) = 0.02466 × t × (D − t) — where D = outside diameter (mm), t = wall thickness (mm), for carbon/alloy steel (density 7.85 g/cm³). For stainless steel (≈7.93–8.00 g/cm³), multiply by the material's actual density ratio.
Skip the manual math — use our free steel weight calculator, flange weight calculator, or metal weight calculator to get an instant, exportable figure for costing and freight planning.
Pipe Dimensions by Material Grade
The dimensional standards above apply consistently across pipe material — but availability, minimum wall thickness and pressure ratings vary by metallurgy. Jump directly to dimension and stock data for the grade you need:
- Stainless Steel Pipes & Tubes
- Carbon Steel Pipes & Tubes
- Alloy Steel Pipes & Tubes
- Duplex Steel Pipes & Tubes
- Super Duplex Steel Pipes & Tubes
- Inconel Pipes & Tubes
- Hastelloy Pipes & Tubes
- Monel Pipes & Tubes
- Copper Nickel Pipes & Tubes
- Nickel Alloy Pipes & Tubes
- Titanium Pipes & Tubes
- Zirconium Pipes & Tubes
- Corten / Weathering Steel Pipes & Tubes
- Aluminium Pipes & Tubes
Browse Pipe Dimension Charts by Schedule
Prefer to see dimensions for one specific schedule only? Use the direct links below — each page has full-range OD/WT/ID data for that schedule:
- Schedule 10 Pipe Dimensions
- Schedule 20 Pipe Dimensions
- Schedule 30 Pipe Dimensions
- Schedule 40 Pipe Dimensions
- Schedule 60 Pipe Dimensions
- Schedule 80 Pipe Dimensions
- Schedule 100 Pipe Dimensions
- Schedule 120 Pipe Dimensions
Industries We Serve
- Oil, gas & petrochemical (refineries, EPC projects, offshore platforms)
- Power generation (boilers, heat exchangers, condenser piping)
- Chemical & fertilizer processing
- Marine & shipbuilding
- Water treatment & desalination
- Pharmaceutical & food-grade process piping
Why Buy Pipe Dimension Data & Pipes From Amardeep Steel
- ISO 9001:2015-certified manufacturing, stocking and export operations.
- EIL-approved pipe supplier for Indian and international EPC contractors.
- In-house dimensional and material testing with third-party inspection (TPI) support on request.
- Seamless, welded (ERW/EFW/LSAW/SAW) and cold-drawn pipe across 15+ metallurgies from a single source.
- Mill Test Certificates (MTC 3.1/3.2) provided with every dispatch.
- 40+ years supplying refineries, EPC contractors and OEM procurement teams globally.
See our certifications, EIL-approved pipe listing and client list.
Download the Full Pipe Dimension Chart
Download the complete Amardeep Steel Pipe Dimension Chart (NPS 1/8"–48", Schedules 5–160, mm & inch, carbon/alloy/stainless) as a print-ready PDF or request it emailed with our current price list.
Frequently Asked Questions
What is the difference between NPS and DN?
NPS (Nominal Pipe Size) is the North American, inch-based nominal designation; DN (Nominal Diameter/Diamètre Nominal) is the metric equivalent used internationally. Both are standardized reference numbers, not the pipe's actual measured diameter, use the NPS–DN conversion table above to move between the two.
What does Schedule 40 pipe mean?
Schedule 40 (Sch 40) specifies a standard wall thickness for a given NPS, per ASME B36.10M. It is the most commonly stocked schedule for general-duty carbon steel piping; Schedule 80 (XS) has a thicker wall for higher-pressure service at the same OD. See our dedicated comparison for schedule 40 vs schedule 80 pipe.
How do I read a pipe size like "NPS 4" x Sch 40"?
This means Nominal Pipe Size 4 inches (OD 114.3 mm, fixed) at Schedule 40 wall thickness (6.02 mm), giving an inside diameter of approximately 102.3 mm. The same pipe can also be expressed as "OD 4.500" x WT 0.237"" or "114.3 mm x 6.02 mm."
Is stainless steel pipe schedule the same as carbon steel pipe schedule?
Not exactly. Stainless pipe follows ASME B36.19M, which uses "S" schedules (5S, 10S, 40S, 80S) that are frequently thinner than the equivalent carbon-steel schedule number under ASME B36.10M — always confirm the standard referenced in your specification.
What is the standard length of a steel pipe?
Pipes are typically supplied in Single Random Length (SRL, approx. 5–7 m / 18–25 ft) or Double Random Length (DRL, approx. 11–13 m / 38–40 ft); cut-to-length is available on request.
How is pipe wall thickness selected?
Wall thickness is selected using the pipe schedule formula (Sch. = design pressure ÷ allowable material stress × 1,000), based on the design pressure, temperature and the allowable stress of the specified material grade, our engineering team can help size wall thickness for your application.
Do you provide Mill Test Certificates with pipe dimension data?
Yes. Every dispatch from Amardeep Steel is supplied with Mill Test Certificates (EN 10204 3.1/3.2) confirming dimensional and material compliance to the ordered standard.
Can you supply pipe in non-standard or custom dimensions?
Yes, in addition to standard NPS/Schedule combinations, we supply custom OD/WT combinations and cut-to-length pipe for OEM and project-specific requirements. Contact our engineering team with your drawing or specification.
Get a Quote for Any Size, Schedule or Material
Have your NPS/DN, schedule and material grade ready? Request a quote and our engineering team will confirm dimensions, availability and lead time or contact us to speak with a piping specialist directly.
