Running Pace Calculator

What this running pace calculator does

Give it any two of pace, distance, and time, and it works out the third — then goes further than a basic calculator with a full split table and a race time predictor. Whether you're planning a training run, working out what pace you need to hit a goal time, or wondering what your 5K speed says about your marathon potential, it's all on one page.

How to use it

• Choose what you want to solve for: pace, finish time, or distance.
• Fill in the other two fields, or tap a distance badge (5K, 10K, half marathon, marathon, 1 mile, 10 mile) to jump straight to a common race distance.
• Toggle "Show a split time for every km/mile" to get a full pacing table for the run — useful for pacing bands or a wrist splits card.
• Scroll down to the Race Time Predictor, enter a recent result, and see your equivalent predicted times at 5K, 10K, 15K, half marathon and marathon using the widely used Riegel formula.

Real-world use cases

A runner training for a 10K wants to know what pace hits a 50-minute goal — solve for pace with distance and time filled in. Someone who just ran a 25-minute 5K wants a realistic marathon goal — the race predictor gives an evidence-based estimate rather than a guess. A coach printing pacing bands for race day uses the split table to hand runners exact checkpoint times.

Frequently asked questions

How accurate is the race time predictor?

It uses Riegel's formula (T2 = T1 × (D2/D1)^1.06), a well-established model for predicting race times across distances from a recent result. It's most accurate when the reference race is run at a similar effort level and fitness to the target race, and gets less precise the further apart the distances are (a 5K time predicting a marathon has more uncertainty than predicting a 10K).

What's the difference between pace and speed?

Pace is time per unit of distance (minutes per km or mile) — the way most runners think about effort. Speed is distance per unit of time (km/h or mph) — more common in cycling. This calculator shows both so you can convert between the two instantly.

Can I calculate my pace in miles if I only know my distance in kilometers?

Yes — enter your distance in either unit, and the result cards show your pace and speed in both km and miles automatically.

Does the split table account for pacing strategy like negative splits?

No, it generates an even-pace table — the same split repeated for every km/mile at your target pace. It's meant as a baseline reference, not a variable pacing plan.

What race distances does the predictor cover?

5K, 10K, 15K, half marathon, and full marathon. You can also enter any custom distance and time as your reference race.