Quick answer: Running pace is the time it takes you to cover one kilometre or mile, usually written as min/km or min/mi. This pace calculator for running works three ways: enter a time and distance to find your pace, a pace and distance to predict a race time, or a pace and time to find the distance. It also converts pace to speed and projects your 5K, 10K, half marathon and marathon times.
Last reviewed: September 2026
Key facts
- Pace is time per unit distance (min per km or min per mile); speed is distance per unit time (km/h or mph) — they are reciprocals of each other.
- 1 mile = 1.60934 km, so a 5:00 min/km pace equals about 8:03 min/mi.
- A race time predictor simply multiplies your pace by the race distance — handy, but real marathon times usually come out slower than the linear projection.
- Most runners improve pace through a mix of easy miles, one weekly faster session, and strength work — never by sprinting every run.
This free running pace calculator solves the three classic runner questions: what is my pace, what time will I run, and how far did I go. Enter any two of pace, time and distance and it calculates the third, converts between min per km and min per mile, shows your speed in km/h and mph, and projects simple linear finish times for the 5K, 10K, half marathon and marathon at your current pace. Results update instantly as you type.
How to use this pace calculator for running
- Choose what to solve for: Pace, Time or Distance.
- Fill in the two known values — time as hours : minutes : seconds, distance in km, miles or metres, pace as m:ss in min/km or min/mi.
- Read your answer at the top, plus the equivalent pace in the other unit and your speed in km/h and mph.
- Check the race time predictor table for your projected 5K, 10K, half marathon and marathon times at that pace.
Pace, speed and distance formulas
The whole calculator rests on three rearrangements of one relationship: pace is simply time divided by distance.
Time = Pace × Distance
Speed = 60 ÷ Pace (min/km) = km/h
Converting pace between units uses the mile definition: 1 mile = 1.60934 km. So min per mile = min per km × 1.60934, and min per km = min per mile ÷ 1.60934. Speed in mph is just 60 divided by your min/mi pace.
Race time predictor: 5K to marathon projections
The predictor table multiplies your current pace by each standard race distance — 5 km, 10 km, 21.0975 km (half marathon) and 42.195 km (marathon). This linear projection is a useful baseline, but treat it as optimistic for long races: fatigue compounds over distance, so real marathon times typically land 5–15% slower than pace × 42.195. Exercise physiologists often use the Riegel formula (T2 = T1 × (D2/D1)1.06) instead, which bakes that fade in — for example, a 25:00 5K predicts a marathon of about 4:00 by Riegel versus 3:31 linearly.
Worked examples
5K in 25:00 — what is the pace?
Pace = 25 min ÷ 5 km = 5:00 min/km. Speed = 60 ÷ 5 = 12.0 km/h. Per mile: 5.00 × 1.60934 = 8.047 min = 8 min 2.8 s, so 8:03 min/mi. Half marathon at the same pace: 21.0975 × 5.00 = 105.49 min = 1:45:29.
Holding 8:00 min/mi — marathon prediction?
Convert to min per km: 8.00 ÷ 1.60934 = 4.971 min = 4 min 58.3 s, so 4:58 min/km. Marathon projection: 42.195 × 4.971 = 209.75 min = 3:29:45. This is the simple linear estimate — expect the real thing to be a few minutes slower unless you have done the long-run training.
What is a good pace? Benchmarks
"Good" depends on age, sex, training history and terrain — but these rough 5K time bands give beginners a target and experienced runners a reality check. Your body mass index also plays a role: carrying less non-functional mass generally means a faster sustainable pace.
| 5K time | Pace (min/km) | Level |
|---|---|---|
| Under 20:00 | Under 4:00 | Advanced club runner |
| 20:00–25:00 | 4:00–5:00 | Intermediate — regular training |
| 25:00–32:00 | 5:00–6:24 | Recreational runner |
| 32:00–40:00 | 6:24–8:00 | Beginner / run-walk |
| Over 40:00 | Over 8:00 | Starting out — every run counts |
For the marathon, breaking 4:00:00 needs about 5:41 min/km; breaking 3:30:00 needs about 4:58 min/km; breaking 3:00:00 needs about 4:16 min/km. Fueling matters as much as fitness at those distances — estimate what a long run costs with a calorie calculator so you eat enough to recover.
Limitations
- Linear projections are optimistic for the half marathon and marathon — hills, heat, wind and fading glycogen all slow you down.
- Treadmill pace vs road pace: treadmills do the pacing for you and remove wind resistance, so road running at the same displayed pace feels harder. Many coaches add ~1% incline to compensate.
- GPS error: phone and watch GPS can drift 1–3%, especially among tall buildings or under tree cover.
- Altitude, heat and humidity slow everyone — compare paces only in similar conditions.
Frequently asked questions
What is a good 5K time for a beginner?
Finishing is the first win — most beginners land between 30 and 40 minutes (6:00–8:00 min/km), often with walk breaks. With 8–12 weeks of consistent easy running, dropping under 30:00 is a realistic next goal. Compare against yourself month to month rather than against club runners.
What is the difference between pace and speed?
Pace is time per distance (min per km), speed is distance per time (km/h). They are reciprocals: speed = 60 ÷ pace-in-min/km. Runners talk pace because "5:00 per km" maps directly onto race splits, while cyclists and drivers use speed. This calculator shows both.
Why does the race time predictor feel too optimistic for the marathon?
Because it is linear — it assumes zero fatigue over 42.195 km. In reality your sustainable pace decays with distance, which the Riegel formula (exponent 1.06) models: a 25:00 5K predicts ~3:31 linearly but ~4:00 by Riegel, and most first-time marathoners land closer to the Riegel number. Bank fitness with long runs, not hope.
How do I convert min per km to min per mile?
Multiply your min per km pace by 1.60934. So 5:00 min/km × 1.60934 = 8.047 min = 8:03 min/mi. To go the other way, divide min per mile by 1.60934: 8:00 min/mi ÷ 1.60934 = 4.971 min = 4:58 min/km. The calculator does both conversions automatically.
How can I improve my running pace?
The proven recipe: mostly easy miles (about 80% of weekly volume), one faster session per week (intervals or tempo), a weekly long run, plus strength training twice a week — stronger legs are more economical legs. Add no more than ~10% weekly distance, sleep well, and retest with this calculator monthly to see the trend.
Is treadmill pace the same as road pace?
Not quite. The belt assists leg turnover and there is no wind resistance, so a given pace feels easier indoors. Set ~1% incline to approximate flat-road effort, and expect outdoor paces to run 10–30 seconds per km slower at the same effort — totally normal, not lost fitness.
Sources
- World Athletics — Official road race distances and competition rules
- Runner's World — Pace charts, race prediction methods and training guidance
- USA Track & Field (USATF) — Long-distance running course standards
Key takeaways
- Pace = time ÷ distance; learn it in min per km and the min per mile conversion follows.
- This race time predictor solves for pace, time or distance — enter any two.
- Linear marathon projections are optimistic; Riegel's formula is the honest version.
- A 5:00/km 5K runner projects roughly 1:45:29 for the half marathon.
- Easy miles, one fast day, long runs and strength work — that is how pace drops.
Related calculators
- One Rep Max Calculator — add strength training to your running with 1RM estimates and training percentages.
- Standard Deviation Calculator — analyze how consistent your pace is across training runs.
- Calorie Calculator — estimate the calories a long run burns so you can fuel and recover.
- Age Calculator — find your exact age for age-graded race time comparisons.
- BMI Calculator — check your body mass index, one factor in sustainable running pace.
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