Speed Distance Time Calculator
Calculate any of speed, distance, or time when given the other two values. Enter values for instant results with step-by-step formulas.
Reviewed for accuracy by Daniel Agrici, Founder & Lead Developer
Speed Distance Time Calculator
Calculator
Adjust values & calculateEnter your values below. Every result is computed in your browser — no data is sent to any server.
Formula: Speed = Distance / Time | Distance = Speed × Time | Time = Distance / Speed
Worked example — 2.5 hours
Formula
Speed = Distance / Time | Distance = Speed × Time | Time = Distance / Speed
Enter any two values to calculate the third. Leave one field empty to solve for it.
Worked Examples
Example 1: Road trip
Problem:60 mph for 150 miles
Solution:Time = 150/60 = 2.5 hours
Result:2.5 hours
Example 2: Solving for required speed
Problem:You need to cover 240 km and have exactly 3 hours available before an appointment. What average speed do you need to maintain?
Solution:Speed = Distance / Time = 240 km / 3 hours
Result:80 km/h required average speed
Frequently Asked Questions
How do I convert between speed units?
mph × 1.609 = km/h. km/h ÷ 3.6 = m/s. mph × 0.447 = m/s.
How do I calculate average speed for a trip with multiple segments?
Average speed is total distance divided by total time, NOT the arithmetic average of segment speeds. For example, driving 60 mph for 1 hour and then 30 mph for 1 hour gives average speed = 90 miles / 2 hours = 45 mph, not (60+30)/2 = 45 mph. However, if each segment covers equal distance (not time), the harmonic mean applies: 2/(1/60 + 1/30) = 40 mph.
What is the stopping distance at different speeds?
Stopping distance = thinking distance + braking distance. At 30 mph: ~23 m total. At 60 mph: ~73 m total. At 70 mph: ~96 m total. Braking distance increases with the square of speed, so doubling speed quadruples braking distance. Wet roads roughly double the braking distance, and reaction time is typically 0.7-1.0 seconds for alert drivers.
How is pace (min/km or min/mile) different from speed?
Speed is distance per unit time (e.g., 10 km/h), while pace is the inverse: time per unit distance (e.g., 6 min/km). Runners typically use pace because it directly tells you how long each kilometer or mile will take. To convert: pace (min/km) = 60 / speed (km/h). A 5-minute mile pace equals 12 mph or 19.3 km/h.
Which of the three variables should I leave blank?
Leave blank whichever value you don't know and want to solve for — the calculator works algebraically in any direction. If you know how far you traveled and how long it took, leave Speed blank to find your average speed. If you know your speed and the distance, leave Time blank to find how long the trip will take. If you know your speed and how much time you have available, leave Distance blank to find how far you can go. Entering all three values is unnecessary since two variables always determine the third under the d = s × t relationship.
Why does my calculated speed differ from a GPS or speedometer reading?
Speed Distance Time Calculator returns average speed over the full distance and time entered, while a speedometer or GPS shows instantaneous speed at a single moment. A trip that includes stoplights, traffic, or rest breaks will always show a lower average speed than the peak speed reached on the open road. For example, a 100-mile trip completed in 2 hours has an average speed of 50 mph even if you spent part of the trip at 70 mph and part of it stopped at a red light — the two effects cancel out in the total-distance-over-total-time calculation.
References
Reviewed for accuracy by Daniel Agrici, Founder & Lead Developer · Editorial policy
Related Calculators
🧮Drive Time Calculator
Estimate driving time between two locations accounting for speed limits and breaks.
🧮Time Zone Travel Time Converter Calculator
Calculate time zone travel time converter with inputs, formulas, and instant results.
🧮Flight Time Calculator
Calculate flight time with inputs, formulas, and instant results.
🧮Route Distance Between Coordinates Calculator
Calculate route distance between coordinates with inputs, formulas, and instant results.
🧮Evcharging Time Calculator
Calculate evcharging time with inputs, formulas, and instant results.
🧮Average Speed Calculator
Calculate average speed with inputs, formulas, and instant results.
🧮Layover Connection Time Calculator
Calculate layover connection time with inputs, formulas, and instant results.
🧮Trip Time Calculator
Calculate trip time with inputs, formulas, and instant results.