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Running Pace Calculator

A premium Running Pace Calculator for runners of every level. Enter a distance and time to instantly get your pace per km and per mile, speed in km/h and mph, and average splits. Predict race times for 5K, 10K, half marathon and marathon using the Riegel formula. Everything runs in your browser — no uploads, no accounts.

Time (h : m : s)

hours

min

sec

Pace / km

5:00

min per km

Pace / mile

8:03

min per mile

Speed

12.0km/h

7.5 mph

Total Time

25:00

5 km

Average Splits

1 km: 5:001 mi: 8:03

Race Time Predictions (Riegel)

5K

5:00 /km

25:00

10K

5:13 /km

52:07

Half Marathon

5:27 /km

1:55:00

Marathon

5:41 /km

3:59:47

Based on the Riegel formula (exponent 1.06). Predictions are estimates — training, terrain, and conditions matter.

Why a 5K time doesn't just scale linearly to a marathon prediction

The Riegel formula's 1.06 exponent is there because fatigue compounds over distance, not just adds up.

It's tempting to predict a marathon time by simply multiplying a 5K pace by 8.4 (the distance ratio), but real race results don't scale that cleanly — endurance degrades faster than distance increases, so a runner's marathon pace is reliably slower than their 5K pace, not just proportionally longer. The Riegel formula this tool uses (T₂ = T₁ × (D₂/D₁)^1.06) builds that extra fatigue factor directly into the exponent, which is why it predicts noticeably more realistic times than naive scaling.

How to use it

  1. Enter a distance and the time it took you to run it — this can be a recent race result or a solid training run.
  2. Read your pace per km and per mile, plus your speed in km/h and mph, computed directly from that input.
  3. Check the race-prediction table for 5K, 10K, half marathon, and marathon times, generated via the Riegel formula from your entered result.
  4. For the most accurate predictions, use a recent race effort as the input rather than an easy training run — the formula assumes race-level effort, and an easy-pace run will under-predict your real race capability.
  5. Use the pace zones below to plan easy, tempo, and interval sessions relative to your current fitness rather than running every session at the same effort.

Pace zones for structured training

  • Easy pace — 60–70% of max heart rate, conversational effort. Most training volume (roughly 80%) should sit here to build aerobic base without accumulating fatigue.
  • Tempo pace — comfortably hard, short-phrase speech only. Improves lactate threshold, the pace you can sustain before fatigue accelerates.
  • Interval pace — hard effort, only a few words at a time. Improves VO2 max and top-end speed.
  • Sprint pace — maximum effort, short bursts. Builds neuromuscular power rather than endurance.

Common use cases

  • Setting a realistic race goal — predicting a marathon or half-marathon finish time from a recent 5K or 10K result before committing to a training plan built around that target.
  • Planning even splits — converting a goal finish time into the exact per-km or per-mile pace needed to hit it.
  • Checking whether a training run is at the right intensity — comparing a run's actual pace against the easy/tempo/interval zones to confirm it matched the intended effort.
  • Converting between pace and speed — for runners using a treadmill (speed-based) alongside outdoor training (pace-based).

Frequently Asked Questions

Everything you need to know about running pace and race predictions

How do I calculate my running pace?
Enter the distance you ran and your total time. Your pace is the time per kilometer (or mile) — for example, running 5 km in 25 minutes gives a 5:00 min/km pace. We also show speed in km/h and mph.
How accurate are the race time predictions?
We use the Riegel formula (T₂ = T₁ × (D₂/D₁)^1.06), a widely used endurance model that predicts race times from a recent race result. Predictions are most accurate when the input is a similar-distance effort. They're estimates — training, terrain, and weather all matter.
What's a good running pace for beginners?
A conversational pace (able to speak in full sentences) is a great starting point — typically 6:30–8:00 min/km for many beginners. Use our calculator to find your current pace, then build consistency before chasing speed.
What's the difference between pace and speed?
Pace is time per unit distance (minutes per km or mile) — the standard way runners talk about effort. Speed is distance per unit time (km/h or mph) — more common in cycling. They're just inverses of each other; use whichever your training plan or watch displays.
Why does my race pace feel harder to hold than my training pace?
Race-day adrenaline, crowds, and taper rest can make an unfamiliar pace feel deceptively easy in the first few kilometers, leading many runners to go out faster than they trained. Pacing off a calculator prediction, rather than how you feel early on, helps avoid that common blow-up in the back half.
Is my data private?
Yes. All calculations happen entirely in your browser. Your running data never leaves your device — no accounts, no uploads.

Tool Overview

A closer look at Running Pace Calculator — how it works, who it's for, and where it fits in your workflow.

Every runner knows the feeling of looking at a finish time and wondering what pace they actually held — or planning a race and needing to know exactly how fast to run each kilometre or mile. The Running Pace Calculator answers both questions: enter a distance and time to get your average pace per km and per mile, your speed in km/h and mph, and your average split times. It's the essential tool for race planning, training analysis, and goal setting.

The race predictor takes it further using the Riegel formula, which estimates your potential finish time for a target distance based on a recent performance at another distance. Run a 5K in 25 minutes, and the predictor tells you what that suggests for 10K, half marathon, and marathon — a proven way to set realistic goals without guesswork. The split calculator breaks down the total distance into per-kilometre or per-mile splits, making it easy to pace yourself during a race or long run.

Whether you're training for your first 5K or aiming for a Boston Qualifier, every calculation runs locally in your browser. Your running data never leaves your device, and there's no sign-up or tracking.

Key Features

Everything you get with this tool, at a glance.

Pace per km & mile

Enter distance and time — get your pace in both units instantly.

Speed (km/h & mph)

See your average speed alongside your pace for a complete picture.

Split Calculator

Per-kilometre or per-mile splits for race-day pacing.

Race Predictions

Riegel formula estimates for 5K, 10K, half marathon, and marathon.

Goal Setting

Use a recent race result to predict what's achievable at other distances.

Private & Local

All calculations run in your browser — no uploads, no sign-up.

How to Use Running Pace Calculator

Get from zero to done in four quick steps — no account, no learning curve.

  1. Enter distance and time

    Input a distance and the time it took you to run it.

  2. Read your pace

    See average pace per km and per mile, plus speed in km/h and mph.

  3. Check your splits

    Review per-kilometre or per-mile splits for the entire distance.

  4. Predict race times

    Use the Riegel formula to estimate your potential at other distances.

Practical Examples

Real input and output pairs so you know exactly what to expect.

10K pace check

Input

Distance: 10 km · Time: 55:00

Output

Pace: 5:30/km (8:51/mi) · Speed: 10.9 km/h

Race prediction

Input

5K: 25:00 → Predict marathon

Output

Predicted marathon: 3:54:00 (Riegel formula)

Half marathon splits

Input

Distance: 21.1 km · Time: 1:50:00

Output

Pace: 5:13/km · 21 splits of 5:13 each

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