Speed, distance and time calculator

The formula

$$d = v\,t$$ $$v = \frac{d}{t}$$ $$t = \frac{d}{v}$$

$d$ is distance, $v$ speed and $t$ time.

Where it comes from

Speed is defined as distance covered per unit of time. 60 miles per hour means 60 miles in each hour. In $t$ hours, you cover that distance $t$ times over, so $d = vt$. The other two forms are the same equation rearranged.

Here $v$ is the average speed. A trip with traffic, stops and highway stretches can still be described by one average speed: the total distance divided by the total time.

Worked example

How long does a 180-mile drive take at an average of 60 mph?

$$t = \frac{180}{60} = 3\ \text{hours}$$

Unit conversions

• 1 mile = 1.609 km, and 60 mph = 96.6 km/h = 26.8 m/s
• To go from km/h to m/s, divide by 3.6.

Watch out for

• Mixed units. Distance in km with speed in mph gives nonsense. The calculator converts for you.
• Averaging speeds. Driving 60 mph there and 40 mph back does not average 50 mph. You spend longer at 40, so the average is 48 mph. Average speed is total distance over total time.

Last checked November 11, 2026