What types of units does this converter handle?

Pressure (MPa, bar, psi, ksi), length (mm, inches, feet, metres), linear weight (kg/m, lb/ft), and temperature (°C, °F) for pipeline and OCTG applications.

What pressure conversion factors are used?

1 MPa = 145.038 psi; 1 bar = 14.5038 psi; 1 ksi = 6.89476 MPa. These are exact SI-to-imperial conversion factors used in API and ASME standards.

What is the kg/m to lb/ft conversion factor?

1 kg/m = 0.6720 lb/ft; equivalently 1 lb/ft = 1.4882 kg/m. This is used for pipe linear weight conversion between metric API and imperial API specification tables.

Steel Pipe Unit Converter

Covers the unit pairs that appear most often in API 5CT and API 5L specifications: pressure (ksi ↔ MPa, bar ↔ psi), linear dimensions (inches ↔ mm), pipe linear mass (lb/ft ↔ kg/m), and temperature (°F ↔ °C). All conversion factors follow SI definitions and are consistent with the values used in API 5CT, API 5L, and ASME B31.8. Results update as you type.

Essential unit conversions for OCTG and pipeline engineering.

Length & Diameter

Inches → mm

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mm → Inches

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Feet → metres

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Metres → feet

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Pressure

ksi → MPa

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MPa

MPa → ksi

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ksi

bar → psi

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psi

psi → bar

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bar

bar → MPa

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MPa

MPa → bar

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bar

Weight & Linear Mass

lb/ft → kg/m

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kg/m

kg/m → lb/ft

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lb/ft

kg → lbs

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lbs

Metric tons → short tons

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Temperature

°C → °F

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°F

°F → °C

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°C

About These Conversion Factors

API 5CT and API 5L publish dimensions in both imperial and SI units, and both unit systems appear on mill test reports, data sheets, and purchase orders from different regional projects. The conversions used here follow SI definitions and match the values used in the API and ASME standards.

Length and diameter: 1 inch = 25.4 mm exactly (SI definition). Pipe OD is the dominant dimension in most OCTG and line pipe specifications. A 9-5/8" casing has OD = 9.625 × 25.4 = 244.475 mm (rounded to 244.5 mm in most tables); a 12" API 5L pipe has OD = 323.9 mm (12.75" × 25.4).

Pressure: 1 ksi = 6.89476 MPa. API 5CT and API 5L historically publish yield strengths in ksi (J55 = 55 ksi minimum yield = 379 MPa; L80 = 80 ksi = 552 MPa; P110 = 110 ksi = 758 MPa). ASME B31.8 and most project specifications in metric-system countries use MPa or bar; 1 bar = 0.1 MPa = 14.5038 psi.

Linear mass (pipe weight): 1 lb/ft = 1.48816 kg/m. API 5CT tabulates casing nominal weight in lb/ft; most project materials lists and shipping documents in metric-system markets use kg/m. For example, 9-5/8" 47 lb/ft casing = 69.9 kg/m nominal.

Worked Example — Converting a Complete Pipe Specification

A purchase order specifies 7" L80 casing at 26 lb/ft with internal yield pressure rated at 7,240 psi. Converting to metric project documentation:

7 inches → mm: 7 × 25.4 = 177.8 mm OD
26 lb/ft → kg/m: 26 × 1.48816 = 38.69 kg/m
7,240 psi → MPa: 7,240 / 145.038 = 49.9 MPa
49.9 MPa → bar: 49.9 × 10 = 499 bar
L80 yield strength 80 ksi → MPa: 80 × 6.89476 = 551.6 MPa (rounds to 552 MPa per API 5CT)

Common Conversion Reference

From	To	Factor	Example
inches	mm	× 25.4	9.625" = 244.5 mm
mm	inches	÷ 25.4	323.9 mm = 12.75"
ksi	MPa	× 6.8948	80 ksi = 552 MPa
MPa	bar	× 10	47.4 MPa = 474 bar
bar	psi	× 14.504	100 bar = 1,450 psi
lb/ft	kg/m	× 1.4882	47 lb/ft = 69.9 kg/m