Convert Newtons per Square Millimetre to ksi (N/mm2 to ksi)

Formula

ksi = N/mm² × 0.1450377377302

or ksi = N/mm² ÷ 6.894757293168

Derivation from SI units:

• 1 N/mm² = 1 N ÷ 10⁻⁶ m² = 10⁶ Pa = 1 MPa
• 1 ksi = 1000 psi = 1 kip/in² = 6.894757293168 MPa
• 1 N/mm² = 1000000 Pa ÷ 6894757.293168 Pa per ksi = 0.1450377377302 ksi

Both units are defined exactly, so the factor is exact. Newton per Square Millimetre definition: newton per square millimetre; ksi definition: ksi.

Worked examples

1. A reading of 30 N/mm² converts to 4.351132132 ksi.
   30 N/mm² × 0.1450377377 = 4.351132132 ksi
2. A value of 275 N/mm² is 39.88537788 ksi.
   275 N/mm² × 0.1450377377 = 39.88537788 ksi

Where it's used

Newtons per Square Millimetre are used for steel yield and tensile strength (S355: 355 N/mm²), while ksi appear in yield and tensile strength in ASTM and ASME material specifications. Both measure pressure, stress and differential pressure (force per unit area), so the conversion is a fixed factor.

Newton per Square Millimetre to other pressure units

Frequently asked questions

Sources

• The International System of Units (SI), 9th edition (SI Brochure), Bureau International des Poids et Mesures , Table 4, coherent derived units with special names.
• Guide for the Use of the International System of Units (SI), NIST Special Publication 811, 2008 Edition, National Institute of Standards and Technology , Appendix B.8, "kip per square inch (ksi)".

Last reviewed: 2026-10-15. Factors are stored exactly and computed with 50-digit decimal arithmetic. See how we verify conversion factors.