What does Schedule 40 mean?

Schedule 40 identifies a wall thickness series tied to nominal pipe size; it is not a fixed 0.40 inch dimension, and the actual thickness varies by NPS, from 0.068 inches at 1/8 inch to over 0.6 inches at 24 inch.

What is the wall thickness of Schedule 40 pipe?

It varies by size. For example, 0.109 inches at 1/2 inch NPS, 0.154 inches at 2 inch NPS, and 0.237 inches at 4 inch NPS.

What is the ID of Schedule 40 pipe?

Inside diameter equals outside diameter minus twice the wall thickness. For 2 inch Schedule 40, ID equals 2.375 minus 2(0.154), or approximately 2.067 inches.

What is the OD of Schedule 40 pipe?

Outside diameter is standardized for each nominal pipe size and is the same across all schedules at that size; for example, 2 inch NPS has a 2.375 inch OD in Schedule 40, 80, and 160 alike.

How much does Schedule 40 pipe weigh per foot?

It varies by size, from approximately 0.24 lb/ft at 1/8 inch NPS to over 170 lb/ft at 24 inch NPS.

What is 2 inch Schedule 40 pipe?

A steel pipe with 2 inch nominal size, 2.375 inch outside diameter, 0.154 inch wall thickness, approximately 2.067 inch inside diameter, and approximately 3.65 lb/ft weight.

What is the difference between Schedule 40 and Schedule 80?

At the same nominal pipe size, Schedule 80 has a thicker wall, smaller inside diameter, and higher weight than Schedule 40, while both share the identical outside diameter.

Is Schedule 40 the same as STD pipe?

For NPS 1/8 through 10, STD (Standard Weight) matches Schedule 40 wall thickness. At NPS 12 and larger, STD diverges from Schedule 40, so the equivalence is size dependent, not universal.

Is Schedule 40 the same as 40S?

No. Schedule 40 belongs to ASME B36.10M for carbon and alloy steel pipe, while Schedule 40S belongs to ASME B36.19M for stainless steel pipe, a separate standard with some differing dimensions at certain sizes.

Does Schedule 40 determine pressure rating?

No, not by itself. Schedule 40 establishes wall thickness; actual pressure capability requires material, grade, temperature, applicable design code, corrosion allowance, and manufacturing specification together.

Is Schedule 40 steel pipe the same size as Schedule 40 PVC?

They generally share the same outside diameter series and nominal sizing convention, but steel Schedule 40 is governed by ASME B36.10M while PVC Schedule 40 is governed by ASTM D1785, and they are separate materials and product standards, not automatically interchangeable products.

How do I measure Schedule 40 pipe?

Measure outside diameter with a caliper or tape, measure wall thickness with a caliper at an accessible end or an ultrasonic thickness gauge for installed pipe, then calculate or directly measure inside diameter.

How do I calculate Schedule 40 pipe weight?

Use the formula weight per foot equals 10.6802 times wall thickness times (outside diameter minus wall thickness), both in inches, for carbon steel, then compare against the standard tabulated value.

Construction Charts

Schedule 40 Pipe Chart 2026 – NPS, OD, Wall, ID & Weight

Q: What is Schedule 40 pipe?

Schedule 40 is a standardized wall thickness designation for steel pipe under ASME B36.10M, identifying a specific wall thickness for each nominal pipe size (NPS).

August 16, 2026

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Schedule 40 Pipe Chart - NPS, OD, Wall, ID & Weight — Schedule 40 Pipe Chart

Schedule 40 Pipe Chart: OD, Wall, ID & Weight | ConcreteCalculate.com

Complete Dimensional Reference (ASME B36.10M)

Schedule 40 Pipe Chart
NPS, OD, Wall, ID & Weight

The complete NPS, DN, outside diameter, wall thickness, inside diameter, and weight reference for Schedule 40 steel pipe, in inches and millimeters.

NPS 1/8″ to 24″Inches & mmlb/ft & kg/mSch 40 vs 80 ComparisonUpdated August 2026

Reviewed by Muhammad Ramzan Babar, PhD Researcher & Calculator Developer · View Profile

⭐⭐⭐ Schedule 40 Pipe Chart: Complete Reference Table

NPS, DN, outside diameter, wall thickness, inside diameter, and weight, per ASME B36.10M.

NPS	DN	OD (in)	OD (mm)	Wall (in)	Wall (mm)	ID (in)	ID (mm)	lb/ft	kg/m
1/8″	6	0.405	10.29	0.068	1.73	0.269	6.83	0.24	0.36
1/4″	8	0.540	13.72	0.088	2.24	0.364	9.25	0.42	0.63
3/8″	10	0.675	17.14	0.091	2.31	0.493	12.52	0.57	0.84
1/2″	15	0.840	21.34	0.109	2.77	0.622	15.80	0.85	1.27
3/4″	20	1.050	26.67	0.113	2.87	0.824	20.93	1.13	1.68
1″	25	1.315	33.40	0.133	3.38	1.049	26.64	1.68	2.50
1-1/4″	32	1.660	42.16	0.140	3.56	1.380	35.05	2.27	3.38
1-1/2″	40	1.900	48.26	0.145	3.68	1.610	40.89	2.72	4.04
2″	50	2.375	60.32	0.154	3.91	2.067	52.50	3.65	5.44
2-1/2″	65	2.875	73.02	0.203	5.16	2.469	62.71	5.79	8.62
3″	80	3.500	88.90	0.216	5.49	3.068	77.93	7.58	11.27
3-1/2″	90	4.000	101.60	0.226	5.74	3.548	90.12	9.11	13.56
4″	100	4.500	114.30	0.237	6.02	4.026	102.26	10.79	16.06
5″	125	5.563	141.30	0.258	6.55	5.047	128.19	14.62	21.75
6″	150	6.625	168.27	0.280	7.11	6.065	154.05	18.97	28.24
8″	200	8.625	219.07	0.322	8.18	7.981	202.72	28.55	42.49
10″	250	10.750	273.05	0.365	9.27	10.020	254.51	40.48	60.25
12″	300	12.750	323.85	0.406	10.31	11.938	303.23	53.53	79.65
14″	350	14.000	355.60	0.437	11.10	13.126	333.40	63.30	94.20
16″	400	16.000	406.40	0.500	12.70	15.000	381.00	82.77	123.18
18″	450	18.000	457.20	0.562	14.27	16.876	428.65	104.67	155.76
20″	500	20.000	508.00	0.594	15.09	18.812	477.82	123.11	183.21
24″	600	24.000	609.60	0.688	17.48	22.624	574.65	171.30	254.92

📌

Standards basis

ASME B36.10M is the authoritative dimensional standard for welded and seamless wrought carbon and alloy steel pipe, including the Schedule 40 series. Values above were calculated and cross-verified against multiple independently published B36.10M based references for accuracy.

🚫

Schedule 40 does not mean 0.40 inch wall thickness

Schedule 40 is a wall-thickness designation, not a pipe diameter of 40/100 inch. Wall thickness varies substantially by NPS, from 0.068 inches at 1/8 inch to 0.688 inches at 24 inch, all under the same “Schedule 40” label.

⭐⭐⭐ What Is Schedule 40 Pipe?

A standardized wall-thickness designation under ASME B36.10M.

NPS

Nominal pipe size, the standardized size label for the pipe.

Outside diameter (OD)

Fixed for each NPS regardless of schedule.

Wall thickness

Determined by the schedule number for that specific NPS.

Inside diameter (ID)

Calculated from OD and wall thickness: ID = OD minus 2 times wall thickness.

⭐⭐⭐ Schedule 40 Pipe Size Relationship

The core chain of dimensional dependency.

📐

NPS → OD → Schedule 40 → Wall Thickness → ID → Weight

Once NPS is known, OD is fixed. Applying Schedule 40 determines the specific wall thickness for that NPS. Wall thickness combined with OD determines ID (via ID = OD minus 2t) and weight per unit length (via the weight formula).

⭐⭐⭐ Schedule 40 Pipe NPS to DN Chart

Cross-referencing the inch based NPS system against the metric DN system.

NPS	DN
1/2″	15
3/4″	20
1″	25
1-1/4″	32
1-1/2″	40
2″	50
3″	80
4″	100
6″	150
8″	200
10″	250
12″	300

⭐⭐⭐ Schedule 40 Pipe NPS vs Actual Outside Diameter

Why isn’t 1 inch pipe actually 1 inch outside diameter?

🚫

NPS is nominal, not the measured OD

1 inch NPS has an actual outside diameter of 1.315 inches, not 1.000 inches. This gap applies across NPS 12 and smaller. At NPS 14 and larger, the nominal size corresponds numerically to the actual OD in inches (14 inch NPS has a 14.000 inch OD).

⭐⭐⭐ Schedule 40 Pipe Inside Diameter Calculation

The formula behind every ID value in this chart.

🧮

Formula and worked example

ID = OD minus 2t. For 2 inch NPS Schedule 40: OD = 2.375 in, wall = 0.154 in. ID = 2.375 minus 2(0.154) = 2.375 minus 0.308 = 2.067 inches, matching the standard tabulated value.

⭐⭐⭐ Schedule 40 Pipe Weight Formula & Calculation

The theoretical relationship behind tabulated weight values.

🧮

Formula

W (lb/ft) = 10.6802 × t × (OD − t), where t and OD are in inches, based on carbon steel density.

2 Inch Schedule 40 Calculation Example

Given: OD = 2.375 in, t = 0.154 in.W = 10.6802 x 0.154 x (2.375 minus 0.154) = 3.65 lb/ft, matching the published reference value.

This formula gives theoretical weight; always use standard tabulated or manufacturer values for procurement and engineering decisions. See the Steel Pipe Weight Chart for the complete weight reference across every schedule.

⭐⭐⭐ Schedule 40 Pipe by NPS

Concise individual reference for the most commonly searched sizes.

1/2 inch Schedule 40 ⭐⭐⭐

OD 0.840 in, wall 0.109 in, ID 0.622 in, 0.85 lb/ft (1.27 kg/m).

3/4 inch Schedule 40

OD 1.050 in, wall 0.113 in, ID 0.824 in, 1.13 lb/ft (1.68 kg/m).

1 inch Schedule 40 ⭐⭐⭐

OD 1.315 in, wall 0.133 in, ID 1.049 in, 1.68 lb/ft (2.50 kg/m).

1-1/2 inch Schedule 40 ⭐⭐⭐

OD 1.900 in, wall 0.145 in, ID 1.610 in, 2.72 lb/ft (4.04 kg/m).

2 inch Schedule 40 ⭐⭐⭐

DN 50, OD 2.375 in, wall 0.154 in, ID 2.067 in, 3.65 lb/ft (5.44 kg/m).

3 inch Schedule 40 ⭐⭐⭐

OD 3.500 in, wall 0.216 in, ID 3.068 in, 7.58 lb/ft (11.27 kg/m).

4 inch Schedule 40 ⭐⭐⭐

OD 4.500 in, wall 0.237 in, ID 4.026 in, 10.79 lb/ft (16.06 kg/m).

6 inch Schedule 40 ⭐⭐⭐

OD 6.625 in, wall 0.280 in, ID 6.065 in, 18.97 lb/ft (28.24 kg/m).

8 inch Schedule 40 ⭐⭐⭐

OD 8.625 in, wall 0.322 in, ID 7.981 in, 28.55 lb/ft (42.49 kg/m).

12 inch Schedule 40 ⭐⭐⭐

OD 12.750 in, wall 0.406 in, ID 11.938 in, 53.53 lb/ft (79.65 kg/m).

16 inch Schedule 40

OD 16.000 in, wall 0.500 in, ID 15.000 in, 82.77 lb/ft (123.18 kg/m).

24 inch Schedule 40

OD 24.000 in, wall 0.688 in, ID 22.624 in, 171.30 lb/ft (254.92 kg/m).

⭐⭐⭐ Schedule 40 vs Schedule 80, STD, XS & 40S

The most important comparison distinctions for Schedule 40.

NPS 2	Wall (in)	ID (in)	Weight (lb/ft)
Schedule 40	0.154	2.067	3.65
Schedule 80	0.218	1.939	5.02

See the complete Steel Pipe Weight Chart for the full Schedule 80 dimensional series.

Schedule 40 vs STD

STD (Standard Weight) matches Schedule 40 for NPS 1/8 through 10. At NPS 12 and larger, STD diverges (0.375 in STD versus 0.406 in Schedule 40 at 12 inch NPS). The equivalence is size dependent, not universal.

Schedule 40 vs XS

XS (Extra Strong) corresponds to Schedule 80, not Schedule 40, for applicable sizes (NPS 1/8 through 8).

Schedule 40 vs XXS

XXS (Double Extra Strong) has substantially thicker walls than Schedule 40, used for the heaviest wall applications within a limited NPS range.

Schedule 40 vs 40S ⭐⭐⭐

Schedule 40 (ASME B36.10M) is for carbon and alloy steel. Schedule 40S (ASME B36.19M) is for stainless steel, a separate standard. The S suffix specifically distinguishes B36.19M dimensions from B36.10M, and some values differ between the two at certain sizes.

Schedule 40 and Schedule 80 2-inch nominal steel pipe comparison showing wall thickness, inside diameter, outside diameter, and relative pressure rating.

⭐⭐⭐ Schedule 40 Pipe Pressure Rating

Schedule 40 is not itself a universal PSI rating.

🚫

Does Schedule 40 mean low pressure? Not necessarily.

Schedule describes wall thickness. Actual allowable operating pressure requires material, grade, temperature, wall thickness, the applicable design code, manufacturing specification, service conditions, and corrosion allowance together. See the Pipe Pressure Rating Chart for the complete material-specific framework.

⭐⭐⭐ Schedule 40 Pipe Applications

Common uses, without implying universal suitability regardless of material, grade, or pressure.

Common applications

Water piping
General utility piping
Compressed air
Process piping
Construction applications
Mechanical systems

Important caveat

Actual suitability for a specific service depends on material, grade, temperature, applicable code, and pressure requirements, not the Schedule 40 designation alone.

⭐⭐⭐ Schedule 40 Steel vs PVC vs Copper

The same phrase, “Schedule 40,” applies to fundamentally different products.

Product	Governing Standard	Material
Steel Schedule 40	ASME B36.10M	Carbon/alloy steel
PVC Schedule 40	ASTM D1785	Polyvinyl chloride

🚫

Do not assume interchangeability

Steel and PVC Schedule 40 generally share the same outside diameter series and nominal sizing convention, but they are governed by entirely separate standards and materials. See the PVC Pipe Size Chart for the complete PVC-specific reference.

Copper tube uses an entirely different sizing convention (K/L/M types, not schedules); see the Copper Pipe Size Chart for that separate system.

Comparison of 2-inch nominal Schedule 40 steel, Schedule 40 PVC, and Type L copper pipes showing outside diameter, inside diameter, wall thickness, pressure rating, and common uses.

⭐⭐⭐ Schedule 40 Pipe Flow Area & Volume

ID determines flow area, not nominal size.

🧮

Flow area formula

A = πD²/4, using the actual Schedule 40 ID for that NPS.

NPS	Sch 40 ID (in)	Flow Area (in²)
1/2″	0.622	0.304
1″	1.049	0.864
2″	2.067	3.36
4″	4.026	12.73
6″	6.065	28.89
8″	7.981	50.03

Actual hydraulic design also requires flow rate, length, fluid, roughness, and fittings; this table provides flow area reference only.

⭐⭐⭐ Schedule 40 Pipe Weight With Water & Coating

Bare pipe weight is not installed system weight.

NPS	Empty Weight (lb/ft)	Water Weight (lb/ft)	Filled Weight (lb/ft)
2″	3.65	0.99	4.64
4″	10.79	3.61	14.40
6″	18.97	8.10	27.07

⚠️

Coatings and fittings add further weight

Galvanizing, paint, epoxy, insulation, and fittings all add mass beyond the bare Schedule 40 pipe weight shown in the base table. See the Steel Pipe Weight Chart for the full discussion of theoretical versus actual weight and support load considerations.

⭐⭐⭐ Identifying & Measuring Schedule 40 Pipe

Practical field methods for confirming Schedule 40.

Check pipe markings.

Look for printed manufacturer, NPS, schedule, grade, standard, and heat/lot information.

Measure outside diameter.

Use a caliper or tape at the largest point of the external thread or pipe body.

Measure wall thickness.

Use a caliper at an accessible cut end, or an ultrasonic thickness gauge for installed or inaccessible pipe.

Determine inside diameter.

Measure directly where accessible, or calculate as ID = OD minus 2t.

Compare against the standard table.

Match OD and wall thickness together against the ASME B36.10M Schedule 40 values for that NPS.

⭐⭐⭐ Schedule 40 Pipe Standards, Tolerances & Grades

Authoritative sourcing and important secondary considerations.

ASME B36.10M

The primary dimensional reference for welded and seamless wrought carbon and alloy steel pipe, defining NPS, OD, wall thickness, schedules, and weights/masses.

ASME B36.19M

The separate stainless steel pipe standard using S suffix schedules; 40S should not automatically be treated as identical to Schedule 40.

Manufacturing tolerances

Published nominal dimensions are not necessarily the exact measured dimensions of every manufactured pipe; OD and wall thickness both carry manufacturing tolerance. Use the applicable product standard or manufacturer documentation for precise procurement.

Material grades

Schedule 40 describes dimensions only; material grade (such as specific ASTM or API product grades for carbon or alloy steel) is a separate specification determining mechanical properties. Not every Schedule 40 pipe has identical strength characteristics.

⭐⭐⭐ Schedule 40 Pipe vs Structural HSS

Process/utility pipe and structural hollow sections are not automatically the same product.

🚫

Do not use a pipe schedule chart for structural HSS design without verification

Structural hollow sections can follow different dimensional and design standards than ASME B36.10M process pipe. Confirm the applicable structural specification before using this chart for structural design purposes.

⭐⭐⭐ Schedule 40 Pipe Visual Guide

Original diagrams explaining Schedule 40 anatomy and key comparisons.

Schedule 40 pipe cross-section: OD fixed by NPS, wall thickness set by Schedule 40, ID derived from both.

Same 2 inch NPS and OD, but Schedule 80 has a noticeably thicker wall than Schedule 40.

Steel Schedule 40 (ASME B36.10M) and PVC Schedule 40 (ASTM D1785) share nominal sizing but are governed by different standards.

⭐⭐⭐ Schedule 40 Pipe Worked Examples

These examples demonstrate the calculation and identification process.

1. Find ID

Given: 2 inch NPS, OD = 2.375 in, wall = 0.154 in.Result: ID = 2.067 in.

2. Find Weight

Given: 2 inch Schedule 40.Result: approximately 3.65 lb/ft.

3. Calculate 20 Foot Pipe Weight

Given: 2 inch Schedule 40 at 3.65 lb/ft, 20 foot length.Result: 3.65 x 20 = approximately 73 lb.

4. Convert to Metric

Given: 3.65 lb/ft.Result: 3.65 x 1.48816 = 5.43 kg/m.

5. Calculate Flow Area

Given: 2 inch Schedule 40, ID = 2.067 in.Result: A = π(2.067)²/4 = 3.36 in².

6. Compare Schedule 40 vs Schedule 80

Given: 4 inch NPS in both schedules.Result: Sch 40: 0.237 in wall, 4.026 in ID, 10.79 lb/ft. Sch 80: 0.337 in wall, 3.826 in ID, 14.98 lb/ft.

⭐⭐⭐ Common Schedule 40 Pipe Mistakes

Most Schedule 40 errors trace back to one of these misunderstandings.

❌ Thinking Schedule 40 means 0.40 inch wall

Wall thickness varies substantially by NPS.

❌ Assuming all Schedule 40 pipe has the same wall thickness

Every NPS has its own specific Schedule 40 wall value.

❌ Confusing NPS with OD

NPS 12 and smaller have an actual OD larger than the nominal number.

❌ Confusing steel Schedule 40 with PVC Schedule 40

Different materials and governing standards despite the shared label.

❌ Confusing Schedule 40 with 40S

Carbon steel versus stainless steel, different standards.

❌ Assuming Schedule 40 automatically means a specific PSI

Pressure rating requires a full design calculation, not a schedule lookup.

❌ Ignoring material grade

Schedule describes dimensions only, not mechanical strength.

❌ Ignoring temperature and corrosion allowance

Both affect actual design suitability beyond nominal dimensions.

❌ Confusing weight per foot with total weight

Multiply by actual length for total quantity.

❌ Assuming actual dimensions equal nominal dimensions

Manufacturing tolerance means real measured values can differ slightly.

Frequently Asked Questions

A standardized wall thickness designation for steel pipe under ASME B36.10M.

It identifies a wall thickness series tied to NPS; not a fixed 0.40 inch dimension.

Varies by size, from 0.068 inches at 1/8 inch NPS to 0.688 inches at 24 inch NPS.

ID = OD minus 2t; for 2 inch NPS, approximately 2.067 inches.

Standardized for each NPS and the same across all schedules at that size.

Varies by size, from approximately 0.24 lb/ft at 1/8 inch to over 170 lb/ft at 24 inch.

2.375 inch OD, 0.154 inch wall, approximately 2.067 inch ID, approximately 3.65 lb/ft.

Same OD, but Schedule 80 has a thicker wall, smaller ID, and higher weight.

Yes for NPS 1/8 through 10; they diverge at NPS 12 and larger.

No, 40S is the separate stainless steel designation under ASME B36.19M.

No, not by itself; pressure rating requires material, temperature, and code together.

They generally share OD conventions but are governed by separate standards (B36.10M vs D1785) and are not automatically interchangeable.

Measure OD and wall thickness with a caliper or ultrasonic gauge, then compare against the standard table.

W (lb/ft) = 10.6802 x t x (OD minus t), then compare against the tabulated standard value.

ASME B36.10M.

📄 Download Schedule 40 Pipe Chart PDF

This PDF is a genuine contractor and engineer reference. Use the print button to create a print-ready or downloadable version.

NPS, DN, OD, OD mmWall thickness, wall mmID, ID mmlb/ft, kg/mSchedule 40 identificationNPS/DN conversionWeight formulaWorked examplesSch 40 vs Sch 80 comparisonStandards note

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Schedule 40 Pipe ChartNPS, OD, Wall, ID & Weight