How do I convert MPa to ksi?

1 ksi = 6.89476 MPa. To convert MPa to ksi: divide by 6.89476. Example: 500 MPa = 72.5 ksi.

What is the difference between MPa and N/mm²?

They are identical. 1 MPa = 1 N/mm² = 1 MN/m². Both are commonly used in engineering for stress and strength values.

How do I convert stress to force?

Force = Stress × Area (F = σ × A). For example, 500 MPa stress on a 100 mm² cross-section: F = 500 × 100 = 50,000 N = 50 kN.

What is kgf/mm² and when is it used?

Kilogram-force per square millimeter. An older metric unit still used in some Russian, Japanese, and older European standards. 1 kgf/mm² = 9.80665 MPa.

What are typical steel strength values?

S235: Rp=235 MPa, Rm=360 MPa. S355: Rp=355 MPa, Rm=510 MPa. AISI 4140 Q&T: Rp=655 MPa, Rm=900 MPa. Stainless 304: Rp=210 MPa, Rm=520 MPa.

Free Engineering Tool

Strength Unit Converter

Convert between 9 stress/strength units instantly. Enter a value in any unit — see all conversions simultaneously. Includes stress-to-force calculator and material reference.

MPa ksi PSI GPa kgf/mm² bar kPa

All Units

MPa (= N/mm²)

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ksi (kip/in²)

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PSI (lbf/in²)

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GPa

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kPa

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bar

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kgf/mm²

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kgf/cm²

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Stress → Force (F = σ × A)

Force

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Force (kN)

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Force (tonnes-force)

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Conversion Relationships

Stress to Force

Practical Example

Example — Converting S355 yield stress

Given: Rp0.2 = 355 MPa

= 355 N/mm² = 0.355 GPa = 355,000 kPa

= 355 / 6.895 = 51.5 ksi = 51,488 PSI

= 355 / 9.807 = 36.2 kgf/mm²

= 355 × 10 = 3,550 bar

Force on 200 mm² bar: F = 355 × 200 = 71,000 N = 71.0 kN

Material Strength Reference Table

Material	Standard	Rp0.2 (MPa)	Rm (MPa)	Rp (ksi)	Rm (ksi)
S235JR	EN 10025	235	360–510	34.1	52–74
S275JR	EN 10025	275	410–560	39.9	59–81
S355JR	EN 10025	355	470–630	51.5	68–91
P265GH	EN 10028	265	410–530	38.4	59–77
P355GH	EN 10028	355	490–630	51.5	71–91
A36	ASTM	250	400–550	36	58–80
A516 Gr.70	ASTM	260	485–620	37.7	70–90
304 SS	EN/ASTM	210	520–720	30.5	75–104
316L SS	EN/ASTM	200	500–700	29.0	73–101
42CrMo4 Q&T	EN 10083	750	1000–1200	109	145–174
AISI 4140 Q&T	ASTM	655	900–1100	95	131–160
Duplex 2205	EN/ASTM	450	620–880	65.3	90–128

💡 Tip: 1 MPa = 1 N/mm² exactly. This is the most common unit for mechanical properties in international standards. In the US, ksi (= 1000 PSI) is standard.

Strength Unit Converter: MPa ↔ ksi ↔ PSI ↔ GPa | Vibromera

Published by Nikolai Shelkovenko on February 15, 2026 March 5, 2026