Running Pace Calculator

Whether you're targeting a PR or estimating your finish time, this calculator computes your pace per mile and per kilometer from any distance and time. It also uses the Riegel formula — the endurance community's gold standard — to predict your finish times for 5K, 10K, half marathon, and marathon based on a recent race result.

Enter Your Measurements

Distance Covered (km)(km)

Total Time (minutes)(min)

Results

Pace per km

5.50

min/km

Pace per mile

8.85

min/mi

Speed

10.9

km/h

Predicted 5K Time

26.4

min

Predicted 10K Time

55.0

min

Predicted Half Marathon

121.4

min

Predicted Marathon

253.0

min

Formula

Pace = Time ÷ Distance | Riegel: T2 = T1 × (D2 ÷ D1)^1.06

How to Use This Calculator

How to Use

1
Enter the distance of your recent run or race in kilometers.
2
Enter your total finish time in minutes.
3
Your pace per km and per mile are calculated automatically.
4
Scroll to the race predictions — these use the Riegel formula with a fatigue factor of 1.06.
5
Predictions assume optimal conditions; hilly or hot courses will slow actual times.

Frequently Asked Questions

How accurate is the Riegel formula?

The Riegel formula (1977) is remarkably accurate for distances within about 3× of your training distance. It tends to underestimate marathon times for runners who haven't specifically trained for the distance, since aerobic efficiency breaks down beyond 90 minutes of sustained effort.

What's a good running pace for beginners?

For new runners, a comfortable conversational pace is more important than speed. A 7–9 min/km pace is typical for beginners. As fitness improves over 8–12 weeks, pace naturally drops. The 80/20 rule applies: run 80% of your miles at easy (conversational) pace and 20% at tempo or faster.

How do I improve my running pace?

Interval training (repeated short efforts at faster than race pace with recovery jogs), tempo runs (sustained effort at lactate threshold), and simply building weekly mileage all improve pace. Most coaches recommend increasing mileage no more than 10% per week to avoid injury.

Why are my predicted times different from my actual races?

The Riegel formula assumes flat courses, ideal weather, and that your base distance reflects your fitness. Hills, heat, wind, poor sleep, under-fueling, and under-training for the target distance all add time. Use predictions as a starting guide for pacing strategy, not as a guarantee.

Related Calculators

VO2 Max Calculator

Calorie Burn Calculator

About This Calculator

This calculator uses the formula: Pace = Time ÷ Distance | Riegel: T2 = T1 × (D2 ÷ D1)^1.06. All calculations follow industry-standard methods. Results are estimates — always verify with a licensed professional for structural or code-compliant work.

Built and maintained by the CalcSmart team. Last updated March 2026.

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