Speed Distance Time Calculator
Solve for speed, distance, or time — enter any two values and get the third instantly. Works for driving, running, cycling, and flying. Updated .
Speed Distance Time — Formula & Guide ()
The relationship between speed, distance, and time is one of the most fundamental formulas in physics and everyday life. Whether you're planning a road trip, training for a race, or doing physics homework, the same three formulas apply — you just choose which variable you need to solve for.
The Three Formulas
💡 Pro Tip: For real trip planning, add 10–15% to your calculated drive time for traffic and add 30 minutes per fuel stop. Pure math never accounts for reality.
All three variables are connected by one relationship: Distance = Speed × Time. Rearranged to solve for each:
Speed = Distance ÷ Time — How fast are you going?
Distance = Speed × Time — How far will you travel?
Time = Distance ÷ Speed — How long will it take?
Common Speed Reference Guide
| Activity | Typical Speed (mph) | Typical Speed (km/h) | Notes |
|---|
| Walking | 2.5–4 | 4–6.4 | Avg ~3 mph |
| Jogging | 4–6 | 6.4–9.7 | 10 min/mile pace = 6 mph |
| Running | 6–10 | 9.7–16 | Elite: 12–15 mph |
| Cycling (casual) | 10–15 | 16–24 | Flat terrain |
| Cycling (fast) | 18–25 | 29–40 | Road bike |
| City driving | 25–35 | 40–56 | With traffic lights |
| Highway driving | 60–75 | 97–121 | US interstate avg |
| Commercial flight | 550–600 | 885–966 | Cruising altitude |
| Sound (sea level) | 767 | 1,235 | Mach 1 |
| Light | 670,616,629 | 1,079,252,848 | In vacuum |
Speed Unit Conversions
| From | To mph | To km/h | To m/s | To knots |
|---|
| 1 mph | — | × 1.60934 | × 0.44704 | × 0.86898 |
| 1 km/h | × 0.62137 | — | × 0.27778 | × 0.53996 |
| 1 m/s | × 2.23694 | × 3.6 | — | × 1.94384 |
| 1 knot | × 1.15078 | × 1.852 | × 0.51444 | — |
How long does it take to drive 300 miles at 65 mph?
Time = Distance ÷ Speed = 300 ÷ 65 = 4.615 hours = 4 hours 37 minutes. This is pure driving time with no stops. For a real road trip, add 15–30 minutes for fuel stops and 10–15 minutes for rest breaks every 2 hours. So realistically, a 300-mile trip at highway speeds takes about 5–5.5 hours door to door.
How do you convert mph to km/h?
Multiply mph by 1.60934 to get km/h. For a quick mental estimate, multiply by 1.6. So 60 mph ≈ 96 km/h, 70 mph ≈ 112 km/h, 100 mph ≈ 161 km/h. To go the other way (km/h to mph), multiply by 0.62137 — or roughly multiply by 0.62 or divide by 1.6.
What is the formula for speed?
Speed = Distance ÷ Time. If you travel 150 miles in 2.5 hours, your average speed is 150 ÷ 2.5 = 60 mph. This gives you average speed — it doesn't account for variations during the trip. If you drove faster on the highway and slower through towns, 60 mph is still your average for the whole journey. Instantaneous speed (what your speedometer reads) is different from average speed.
How far can you drive in 8 hours?
Distance = Speed × Time. At 65 mph for 8 hours: 65 × 8 = 520 miles. At 70 mph: 560 miles. In practice, accounting for fuel stops, food, and rest breaks (recommended every 2 hours), you'd realistically cover 450–500 miles in an 8-hour travel day at highway speeds. The FMCSA (commercial driving rules) limits truck drivers to 11 hours of driving per day for safety reasons.
How do I calculate how long a trip will take?
Time = Distance ÷ Average Speed. Get the distance from Google Maps or similar, then estimate your average speed accounting for the road type. For a mixed route (city + highway), use 45–50 mph as your average. For mostly highway, use 55–65 mph. Add 10–15% for traffic, construction, and delays. Then add stop time separately — about 30 minutes per fuel stop and 15 minutes per rest break. The calculator above uses pure driving time; always add stop time for real trip planning.