What this calculator does
Find out how long a trip will take, how far you'll go, or how fast you went. Speed, distance and time are tied together by one simple rule: distance equals speed times time. Know any two, and you can find the third. That answers everyday questions. How long will a 210-mile drive take? How far does a train go in 45 minutes? What average speed did a runner keep up over a race?
Choose what you want to find, then enter the other two values. You can use miles or kilometers, mph or km/h, and hours and minutes. When you find the travel time, the calculator also adds it to your departure time. That gives your arrival time, rolling over to the next day when needed.
Where it's used
Why this math matters outside the classroom:
- Road trips. Drivers covering 210 miles at an average of 60 mph plan on 3.5 hours, or 3 h 30 min, behind the wheel.
- Running races. A runner who finishes 42.195 km in 3 h 30 min averaged about 12.06 km/h.
- Commuting. Cyclists riding 9 miles at 12 mph allow 0.75 hours, which is 45 minutes, to get to work.
- Science class. Students find that a train traveling 80 km/h for 2.5 hours covers 80 × 2.5 = 200 km.
- Delivery planning. Dispatchers divide a 150 km route by 75 km/h to schedule a 2-hour run and set the arrival time.
Grade level and standards: Grades 6–7; Common Core State Standards for Mathematics 6.RP.A.3.b. © Copyright 2010. National Governors Association Center for Best Practices and Council of Chief State School Officers. All rights reserved.
How to use it
- Choose whether you want to find the travel time, the distance or the average speed.
- Enter the values you know and pick their units. You can mix distance and speed units. The calculator converts them for you.
- For travel time, set the departure time to get the arrival time.
- Read the result. If it helps, you can also read the same answer in the other units.
What the inputs mean
- Average speed
- For a realistic travel time, use your average speed for the whole trip. It's usually well below the speed limit once you count traffic, towns and stops. For a highway drive with light traffic, a few miles per hour under the limit is a common rough guess.
- Time: hours
- Time is entered as whole hours plus minutes. A trip of 1.5 hours is 1 hour and 30 minutes.
- Departure time
- Enter the departure time in 24-hour form, or use the time picker. The arrival shows on a 12-hour clock. It says "next day" when the trip crosses midnight.
Formula and method
distance = speed × time time = distance ÷ speed average speed = distance ÷ time 1 mile = 1.609344 km (exact) time in hours = hours + minutes ÷ 60
The three formulas are the same rule, just turned around. Speed is a rate: the distance you cover each hour. So speed times hours gives the distance. And distance divided by speed tells you how many hours it takes.
The units have to match: miles with miles per hour, kilometers with kilometers per hour. When they don't, the calculator converts the distance first. It uses the exact length of the international mile, 1.609344 km.
A travel time comes out in decimal hours, such as 3.5 h. Multiply the part after the decimal point by 60 to get minutes (0.5 h = 30 min). Do the same with any leftover part of a minute to get seconds. The calculator rounds to the nearest second.
Average speed is the total distance divided by the total time. It isn't the average of the speeds on each leg, unless every leg took the same amount of time.
Worked example
A family drives 210 miles at an average of 60 mph, leaving at 9:00 AM. When will they arrive?
- Time = distance ÷ speed = 210 mi ÷ 60 mph = 3.5 hours.
- 0.5 hour × 60 = 30 minutes, so the trip takes 3 h 30 min.
- 9:00 AM + 3 h 30 min = 12:30 PM.
Result: The drive takes 3 h 30 min, arriving at 12:30 PM.
Understanding the result
The travel time is the time spent moving at the average speed you entered. Add time for fuel, food and rest stops on top. Or lower the average speed to cover them.
Finding the speed gives the average over the whole time you entered. So a trip with a long stop will show a lower average than your speedometer did.
When you find the speed, you also see minutes per mile (or per kilometer). That's your pace, the measure runners and walkers usually use.
Assumptions and limitations
- Speed stays at the average you entered, or that number is the average over the whole trip.
- The departure and arrival times are in the same time zone.
- Traffic, weather, stops and speed changes aren't included. The result is only as good as the average speed you enter.
- Arrival times don't account for crossing time zones or daylight-saving changes during the trip.
Frequently asked questions
How long does it take to drive 100 miles?
At an average of 60 mph, it takes 100 ÷ 60 = 1.67 hours, or 1 h 40 min. At 50 mph, it takes 2 hours. Enter your own average speed for a better estimate.
How do I convert decimal hours to hours and minutes?
Keep the whole hours and multiply the decimal part by 60. For example, 2.75 hours is 2 hours plus 0.75 × 60 = 45 minutes.
Why isn't my average speed the average of my two speeds?
Because you spend longer at the slower speed. Say you drive 60 miles at 30 mph, then 60 miles at 60 mph. That takes 2 h + 1 h = 3 h for 120 miles. Your average is 40 mph, not 45.
How do I change km/h to mph?
Divide by 1.609344. For example, 100 km/h ÷ 1.609344 ≈ 62.14 mph. The calculator does this for you when the units are mixed.
How this calculator is checked
Method: Constant-speed relationship d = s × t; international mile = 1.609344 km exactly. The calculation is covered by automated tests with known reference values and edge cases. Last updated 2026-10-18. Found a problem? Tell us.
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