Convert Stokes to Square Millimeters per Second

Formula

mm²/s = St × 100

Derivation from SI units:

• 1 St = 1 cm²/s = 10⁻⁴ m²/s
• 1 mm²/s = 10⁻⁶ m²/s = 1 cSt
• 1 St = 0.0001 m²/s ÷ 0.000001 m²/s per mm²/s = 100 mm²/s

Both units are defined exactly, so the factor is exact. Stokes definition: stokes; Square Millimeter per Second definition: square millimeter per second.

Worked examples

1. A reading of 0.5 St converts to 50 mm²/s.
   0.5 St × 100 = 50 mm²/s
2. A value of 5 St is 500 mm²/s.
   5 St × 100 = 500 mm²/s

Where it's used

Stokes are used for older physics and fluid-mechanics references, while square millimeters per second appear in lubricant ISO VG grades (VG 32, 46, 68 …). Both measure kinematic viscosity (dynamic viscosity divided by density), so the conversion is a fixed factor.

Stokes to other kinematic viscosity units

Frequently asked questions

Sources

• 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, "stokes (St)".
• The International System of Units (SI), 9th edition (SI Brochure), Bureau International des Poids et Mesures , Table 2 with SI prefix milli.

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