Speed Distance Time Calculator
Choose what you want to solve for, enter the other two values, and the answer updates as you type. The link in your address bar always reflects your numbers.
How this calculator works
Distance, speed, and time are locked together by one equation: d = r × t. If you know any two of the three, you can always solve for the third by rearranging that same formula — divide when you're isolating rate or time, multiply when you're isolating distance. This calculator does that rearranging for you: pick which value is unknown, enter the other two, and it applies the right version of the formula instantly.
Worked examples
The three modes are just three faces of the same relationship, so the same numbers work in all of them. Start with a trip of 240 miles at 60 mph:
- Solve for time: 240 mi ÷ 60 mph = 4 hours.
- Solve for speed: 240 mi ÷ 4 hr = 60 mph.
- Solve for distance: 60 mph × 4 hr = 240 miles.
Notice all three modes agree on the same trip — that's the self-consistency check built into the math. Change any one value in the calculator and the other relationships still hold.
Frequently asked questions
What's the formula behind this calculator?
It's the fundamental distance–rate–time relationship: d = r × t, where d is distance, r is speed (rate), and t is time. Rearranged, that gives r = d ÷ t and t = d ÷ r — the same equation solved for a different unknown. It's one of the first formulas taught in basic algebra and physics, and it holds exactly whenever speed is constant (or you're working with an average speed).
Does this work in km/h too, or only mph?
The math is unit-agnostic — d = r × t holds no matter which units you use, as long as you stay consistent (all metric or all imperial, never mixed). This tool labels its fields in miles, mph, and hours by default, but you can mentally swap in kilometers and km/h and the arithmetic is identical.
How is this different from a road-trip planner?
This tool is the pure math relationship for exactly two known values — plug in any two of speed, distance, or time and it solves the third instantly. A real road trip has stops for gas, food, and rest, which stretch the actual travel time beyond the raw calculation. For that fuller picture, see our road-trip-time-calculator, which factors stop time into the estimate.
Can I enter time in minutes instead of hours?
This calculator's time field uses hours, since that keeps the formula's units consistent with miles and mph. To enter minutes, just convert first — divide by 60 to get decimal hours. For example, 90 minutes is 1.5 hours, and 15 minutes is 0.25 hours. Decimal values like these are accepted directly.