Speed Distance Time Calculator

Step 1: Select what you want to solve for: Distance, Speed, or Time.

Step 2: Enter the two known values. The calculator shows only the fields you need — the unknown value is what gets calculated.

Step 3: Click Calculate. The result shows the unknown value with a breakdown of all three values.

Speed, distance, and time are connected by one of the most fundamental formulas in physics: Distance = Speed × Time. If you know any two of these values, you can calculate the third.

Speed (or velocity) measures how fast something moves, typically in miles per hour (mph) or kilometers per hour (km/h). A car traveling at 60 mph covers 60 miles every hour.

Distance measures how far something travels, in miles, kilometers, or other length units. This is the total path length, not the straight-line distance between start and end (which would be displacement).

Time is how long the travel takes, typically in hours. For speeds in mph, time must be in hours. A 30-minute drive is 0.5 hours.

Average speed vs constant speed: This formula uses average speed. If you drive 60 mph for the first hour and 40 mph for the second hour, your average speed is 50 mph and your distance is 100 miles in 2 hours. Real driving involves varying speeds, but the formula works perfectly with averages.

This formula assumes constant or average speed. For accelerating objects (like a car from a stoplight or a falling object), more complex physics equations involving acceleration are needed.

The three forms of the same equation:

Distance = Speed × Time
How far? If you drive 65 mph for 3 hours: 65 × 3 = 195 miles

Speed = Distance ÷ Time
How fast? If you traveled 180 miles in 2.5 hours: 180 ÷ 2.5 = 72 mph

Time = Distance ÷ Speed
How long? If you need to travel 240 miles at 60 mph: 240 ÷ 60 = 4 hours

Unit consistency is critical. If speed is in mph, distance must be in miles and time in hours. If speed is km/h, distance is km and time is hours. Do not mix miles and kilometers.

Converting minutes to hours: Divide by 60. 45 minutes = 0.75 hours. 90 minutes = 1.5 hours. 20 minutes = 0.333 hours.

Example 1: Solve for Distance
Driving at 65 mph for 4.5 hours. Select "Distance." Enter speed 65, time 4.5. Result: 292.5 miles.

Example 2: Solve for Speed
You drove 180 miles and it took 2 hours 45 minutes (2.75 hours). Select "Speed." Enter distance 180, time 2.75. Result: 65.45 mph.

Example 3: Solve for Time
You need to drive 350 miles and plan to average 70 mph. Select "Time." Enter distance 350, speed 70. Result: 5 hours exactly.

Convert minutes to hours before entering. This calculator uses hours for time. Divide minutes by 60: 30 min = 0.5h, 45 min = 0.75h, 90 min = 1.5h.

Use average speed for real trips. Your car's speedometer varies throughout a trip. Use the average speed you expect to maintain. For highway trips, 60-70 mph is typical.

Account for stops. If your 300-mile trip includes a 30-minute rest stop, add 0.5 hours to your calculated travel time.

Speed limits affect your calculations. Plan using the speed limit, not your desired speed. A trip at 80 mph saves surprisingly little time over 65 mph due to the math of diminishing returns.

Unit consistency matters. If you enter speed in mph, distance must be in miles and time in hours. Do not mix units.