Speed Converter
Convert speeds between km/h, mph, m/s, knots, ft/s and Mach. Built for drivers, pilots, sailors and runners.
Educational estimate. Calculator results are for planning and information only, not financial, tax, medical, legal, or engineering advice. Verify important decisions with official sources or a qualified professional.
Speed Converter
km/h, mph, m/s, knots, ft/s
📐 Formula & Method
Linear conversion
All units are stored as a multiplier against an internal base unit. To convert, the input is first scaled to the base, then divided by the target factor.
📋 How to Use
-
1
Enter the numeric value you want to convert.
-
2
Pick the source unit in the From dropdown.
-
3
Pick the target unit in the To dropdown.
-
4
Click Calculate. You will see the result, a full conversion table to every supported unit, and a list of common conversions.
💡 Key Insights
-
1 mph = 1.60934 km/h; 1 km/h = 0.62137 mph.
-
1 knot = 1 nautical mile per hour = 1.852 km/h ≈ 1.151 mph.
-
Mach 1 at sea level (15 °C) is ~1,225 km/h or 761 mph — speed of sound in dry air.
-
A useful rule: km/h × 0.6 ≈ mph (only ~3% off).
🔬 Methodology & Accuracy
Formula: Linear unit conversion with high-precision constants. All math runs client-side in your browser using IEEE-754 doubles.
Data sources: BIPM SI brochure (9th ed.); NIST SP 811 (2008 ed.); ISO 80000-1 quantities and units.
Last reviewed: January 2026 · Accuracy: Results are precise to two decimal places using IEEE-754 double-precision arithmetic. Intended for educational and planning use only.
For informational purposes only. Results are estimates based on the inputs and formulas provided. For financial, tax, medical, or legal decisions, consult a qualified professional. Rates and regulations change — always verify current figures with official sources.
Accuracy & Feedback
❓ Frequently Asked Questions
Complete your Conversion picture
These tools naturally pair with the Speed Converter — use them in order to get a full view.