Running Pace Calculator with Race Predictions
Enter your distance and finish time to instantly see your running pace in both metric and imperial units, your equivalent speed, projected finish times for four classic race distances, and a full per-kilometre split table — all based on your actual effort.
Finish time
Pace
5:00 /km
Speed
12.00 km/h
7.46 mph
Pace / mile
8:03 /mi
Race predictions (equal pace)
| Distance | Predicted time |
|---|---|
| 5K | 25:00 |
| 10K | 50:00 |
| Half Marathon | 1:45:29 |
| Marathon | 3:30:59 |
Cumulative time by km
Per-km split table
| Km | Cumulative time |
|---|---|
| 1 | 5:00 |
| 2 | 10:00 |
| 3 | 15:00 |
| 4 | 20:00 |
| 5 | 25:00 |
| 6 | 30:00 |
| 7 | 35:00 |
| 8 | 40:00 |
| 9 | 45:00 |
| 10 | 50:00 |
How it works
Pace and speed describe the same quantity from opposite directions. Pace tells you how long it takes to cover one unit of distance — typically expressed as minutes per kilometre (or per mile) — while speed tells you how much distance you cover in one unit of time, such as kilometres per hour. For runners, pace is usually the more actionable number: you can directly match it to a treadmill setting, a GPS watch target, or a race strategy. Speed is useful for comparing efforts across different sports or when reading race data published by timing services that use km/h. This calculator gives you both, derived from the same division: pace = total seconds ÷ distance; speed = distance ÷ hours elapsed.
The race predictions on this page assume you maintain exactly the same pace for every kilometre of every distance. That assumption is a useful starting point but will systematically overestimate performance for longer races. Physiological fatigue, pacing errors, and nutritional demands mean that very few runners can hold 5K effort across a half marathon or marathon. A well-known empirical correction is Riegel's formula (t₂ = t₁ × (d₂/d₁)^1.06), which applies a mild penalty as distance grows. The predictions here do not apply that correction: they reflect pure equal-pace arithmetic so you can see a clean baseline. Think of them as a best-case ceiling rather than a reliable target, especially for the marathon.
Splits reveal how a race actually unfolds. A negative split — running the second half faster than the first — is widely regarded as the most efficient and least painful way to race, because it avoids the early lactate accumulation that causes late-race fade. An even split, where each kilometre takes the same time, is mathematically optimal under the pure-pace model this calculator uses. In practice, most recreational runners go out too fast and post a positive split (first half faster than second), losing more time in the final kilometres than they gained at the start. Reviewing the cumulative split table below is a practical way to design a race plan: identify a target split, find the cumulative time at each checkpoint, and program those into your GPS watch or memorise the key splits before race day.
Frequently asked questions
Are the race predictions realistic?+
They are optimistic for longer distances. The projections assume you hold your current pace for every single kilometre, which does not account for fatigue, fuelling requirements, or the psychological difficulty of maintaining effort late in a race. Empirical models like Riegel's formula show that performance degrades as distance increases — roughly by a factor of (d₂/d₁)^1.06. As a practical rule: your 5K-to-10K projection is fairly reliable; your half-marathon projection may be off by a few minutes; your marathon projection could be off by 10–20 minutes or more if your training is not specifically marathon-focused. Use these numbers as a ceiling to plan around, not a guarantee. This tool provides training estimates only, not medical advice — consult a physician before starting a new training program.
What is a good 5K pace?+
This varies so widely that a single answer is unhelpful. Elite men run sub-2:50/km (under 14:00 for 5K); elite women run under 3:10/km. A solid club-level runner might target 3:30–4:30/km. Most recreational runners completing their first 5K race land in the 6:00–8:00/km range, and many finish by run-walking at 8:00–10:00/km or beyond. The most relevant benchmark is your own progression over time: if your pace improves on the same course in similar conditions, your fitness is improving regardless of where it sits on any external scale. Focus on consistency and gradual improvement rather than arbitrary pace targets.
Is treadmill pace the same as outdoor pace?+
Not quite. Treadmill running is generally slightly easier than outdoor running at the same displayed speed because the belt assists leg turnover and there is no wind resistance or terrain variation. Studies suggest adding roughly 1% grade (a 1% incline) to a treadmill compensates for the missing wind resistance on flat outdoor runs. Temperature, surface, and shoe choice also affect outdoor pace. Treadmill pace is a useful training reference but do not expect a treadmill personal best to translate directly to a road race — most runners find road conditions feel modestly harder at the same pace.