Enter any two values and this calculator finds the third. All fields accept decimals.
How fast are you going, how far will you travel, and how long will it take to get there? One simple relationship links all three, and the free tool at the top of this page solves any of them in seconds. Below are the formulas, step-by-step instructions, unit conversions, and worked examples.
Quick answer: A speed distance time calculator finds the missing value when you know the other two: enter distance and time to get speed, speed and time to get distance, or distance and speed to get time. The tool above also converts between km/h, mph, m/s, kilometers, miles, meters, hours, and minutes.
How to Use This Calculator
The calculator has three modes. Pick the tab that matches what you want to find, then fill in the two values you already know.
Solve for Speed
- Select the Solve for Speed tab.
- Enter the distance traveled and choose kilometers, miles, or meters.
- Enter the time it took and choose hours or minutes.
- Pick the speed unit you want the answer in: km/h, mph, or m/s.
- Click Calculate Speed. The result shows in your chosen unit plus the other two units.
Solve for Distance
- Select the Solve for Distance tab.
- Enter the speed and choose km/h, mph, or m/s.
- Enter the travel time in hours or minutes.
- Choose whether to see the distance in kilometers, miles, or meters.
- Click Calculate Distance. You get the answer in your unit plus equivalents in the other two.
Solve for Time
- Select the Solve for Time tab.
- Enter the distance in kilometers, miles, or meters.
- Enter the speed in km/h, mph, or m/s.
- Choose hours or minutes for the answer, then click Calculate Time.
- The result shows both a decimal answer and a friendly hours-and-minutes breakdown, such as 4 h 18 min.
To start over, click Clear. Every input must be a positive number; the calculator shows a friendly message if a field is empty or zero.
The Speed, Distance, and Time Formulas
All three formulas come from one relationship:
- Speed = Distance / Time
- Distance = Speed x Time
- Time = Distance / Speed
A classic memory trick is the speed distance time triangle: write S on top with D and T below. Cover the value you want to find. D and T side by side means multiply; one over the other means divide.
Keep units consistent: 30 miles in 45 minutes is 30 miles in 0.75 hours, giving 40 mph. The calculator above converts automatically.
Worked Examples You Can Verify
Every row in this table uses the exact formulas above. Try any of them in the calculator to confirm.
| Distance | Time | Speed | Check |
|---|---|---|---|
| 120 km | 2 h | 60 km/h | 120 / 2 = 60 |
| 180 miles | 3 h | 60 mph | 180 / 3 = 60 |
| 100 m | 10 s | 36 km/h (10 m/s) | 100 / 10 = 10 m/s; 10 x 3.6 = 36 |
| 150 miles | 2.5 h | 60 mph | 150 / 2.5 = 60 |
| Speed | Time | Distance | Check |
|---|---|---|---|
| 60 mph | 3 h | 180 miles (289.68 km) | 60 x 3 = 180 |
| 100 km/h | 45 min | 75 km (46.60 miles) | 100 x 0.75 = 75 |
| 5 km/h | 40 min | 3.33 km (2.07 miles) | 5 x 40/60 = 3.33 |
| Distance | Speed | Time | Check |
|---|---|---|---|
| 300 km | 100 km/h | 3 h | 300 / 100 = 3 |
| 280 miles | 65 mph | 4 h 18 min (4.31 h) | 280 / 65 = 4.31; 0.31 x 60 = 18.6 |
| 790 miles | 70 mph | 11 h 17 min (11.29 h) | 790 / 70 = 11.29; 0.29 x 60 = 17.4 |
Units You Can Convert Between
The calculator converts results automatically, but it helps to know the key factors:
| Conversion | Factor | Example |
|---|---|---|
| mph to km/h | multiply by 1.609344 | 60 mph = 96.56 km/h |
| km/h to mph | multiply by 0.621371 | 120 km/h = 74.56 mph |
| m/s to km/h | multiply by 3.6 | 10 m/s = 36 km/h |
| miles to kilometers | multiply by 1.609344 | 180 miles = 289.68 km |
| minutes to hours | divide by 60 | 45 min = 0.75 h |
| hours to minutes | multiply by 60 | 3 h = 180 min |
Frequently Asked Questions
What is the formula for speed?
Speed equals distance divided by time. If you drive 120 kilometers in 2 hours, your speed is 120 / 2 = 60 km/h. The same formula works in any consistent units: miles per hour, meters per second, or feet per second.
How do I calculate distance if I know speed and time?
Multiply speed by time. Driving at 65 mph for 2.5 hours covers 65 x 2.5 = 162.5 miles. Convert the time to the same unit as the speed first: 45 minutes of driving at 100 km/h is 100 x 0.75 = 75 km.
How do I find travel time from distance and speed?
Divide distance by speed. A 300-mile trip at 60 mph takes 300 / 60 = 5 hours. Add extra time for stops: two 15-minute breaks turn 5 hours of driving into 5.5 hours of travel.
What is the difference between speed and velocity?
Speed is how fast you move; velocity is speed plus direction. A car circling a track at a steady 60 mph has constant speed but constantly changing velocity because its direction changes. For everyday trip math, speed is what you need.
Can average speed be higher than my top speed?
No. Average speed is total distance divided by total time, so it can never exceed the fastest speed you reached. If your speedometer touched 70 mph but traffic slowed you down, your average for the trip will be lower, for example 60 mph over 120 miles in 2 hours.
Why does the calculator show results in multiple units?
Showing km/h, mph, and m/s (or kilometers, miles, and meters) side by side saves a second conversion step. It is handy for comparing race results, reading foreign road signs, or checking aviation and boating speeds.
Learn More
- How to Calculate Speed: Formula Explained - step-by-step speed formula guide with driving, cycling, and sprinting examples.
- How to Calculate Distance from Speed and Time - worked distance examples for road trips, flights, and running.
- How Long Will My Trip Take? Formula Guide - trip-time planning with stops, flights, and real routes.
- Average Speed vs Instantaneous Speed Explained - what your speedometer shows versus your trip average.
- How to Convert MPH to KPH and Knots - unit conversion factors, tables, and quick-reference values.