How accurate are the conversions?

Conversions use standard SI-defined ratios (e.g., 1 inch = 0.0254 m exactly). Temperature conversions use the standard offset formulas (°F = °C × 9/5 + 32). Results are accurate to JavaScript's 64-bit float precision.

Can I convert temperature units?

Yes. Select the Temperature category and choose from Celsius, Fahrenheit, Kelvin, or Rankine. The converter handles the non-linear offset formulas automatically.

What units are supported?

Length: mm, cm, m, km, in, ft, yd, mi, nautical miles. Weight: mg, g, kg, t, oz, lb, stone. Temperature: °C, °F, K, °R. Volume: ml to gallons. Area: mm² to square miles. Speed: m/s, kph, mph, knots, fps. Other: Nm and ft·lbs torque.

Does this work without internet?

Yes. Once the page loads, all calculations run locally in your browser. You can save it as a bookmark and use it offline.

Why do some conversion results have many decimal places?

Most unit ratios are irrational numbers (e.g., 1 mile = 1609.344 m). The result shows the full precision. Round to your needed decimal places for practical use.

MPH to KM/H

Convert mph to km/h instantly. Free speed converter for driving, running, cycling, and motorsports reference.

From

1.609344

1 mph = 1.609344 km/h

Miles per hour (mph) to kilometers per hour (km/h) is the definitive speed unit conversion for US-to-international travel and motorsports. One mph = 1.60934 km/h. Highway speed limits: US Interstate highways are typically 65–75 mph (105–121 km/h); European motorways 120–130 km/h (75–81 mph). Formula 1 top speeds reach approximately 360 km/h (224 mph). Running pace: a 6-minute mile is 10 mph (16.1 km/h); elite marathon pace is about 12.5 mph (20.1 km/h). Wind speed in weather forecasts is reported in mph in the US and km/h internationally. A Category 1 hurricane has sustained winds of 74–95 mph (119–153 km/h). Baseball pitch speed: a 100 mph fastball = 161 km/h.

Related Conversions

KM/H to MPH Kilometers to Miles Miles to Kilometers Meters to Feet Feet to Meters

Free Online Unit Converter

Zolkit's unit converter supports 7 categories covering dozens of the most common conversions — length, weight, temperature, volume, area, speed, and torque. Pick a category, select your units from the dropdowns, type a value, and see the result instantly. A swap button reverses the conversion direction with one click. Your last-used category and units are remembered locally so the converter is ready when you return.

7 Unit Categories

Convert length, weight, temperature, volume, area, speed, and torque — all the unit conversions you need in one tool.

Instant Conversion

Results update as you type. Switch between units with dropdowns and see the converted value immediately.

Swap Units

Hit the swap button to instantly reverse the conversion direction. Saves time when you need both directions.

Offline-Ready

All conversions are calculated locally in your browser. No internet required after the page loads.

Works on Any Device

Clean, responsive layout that works on phones, tablets, and desktops alike.

Always Free

No account required, no ads, no limits. Convert as many units as you need, whenever you need.

How to Use the Unit Converter

1
Choose a unit category from the tab bar at the top: Length, Weight, Temperature, Volume, Area, Speed, or Other.
2
Select the unit you're converting from and the unit you're converting to using the dropdowns. Type your value and the result appears instantly.
3
Click the swap button (↔) to reverse the conversion direction, or click Copy to save the result to your clipboard.