What Riegel exponent should I use?

1.06 is a common recreational default. Well-trained endurance athletes sometimes use values closer to 1.05–1.08.

Is projection a guarantee?

No. It is a simple scaling estimate.

Can it build my training plan?

No. It only does pace math and optional distance projection.

Free Calculators Hub

Running Pace Calculator

Turn a finish time into clear pace and speed—and optionally project another distance with Riegel’s rule of thumb.

Pace & speed

Any km distance

Optional race projection

Computes pace and speed from distance and clock time, with optional Riegel projection to another distance. Not a VO2max or coaching plan.

Limitation: Educational running arithmetic only.

Jump to calculator · Sources & review

Free Calculators HubRunning Pace Calculator

Distance (km)Race or training distance in kilometers (e.g., 5, 10, 21.0975, 42.195).HoursMinutesSecondsOptional target distance (km)Set 0 to skip Riegel projection.Riegel exponentTypical recreational default 1.06.

How to Calculate Pace

Enter one known performance, then optionally a second distance to project.

Enter distance in kilometers.

Convert miles first

If your race is in miles, convert to km (×1.60934) before entering distance.

What Pace and Projection Mean

Pace is average time per kilometer for the entered run. Projection applies a simple endurance scaling law—not a physiology lab result.

Running Pace Examples

50-minute 10K

Entered run

distanceKm:10

hours:0

minutes:50

seconds:0

targetDistanceKm:0

enduranceExponent:1.06

Pace (min/km)

5.000 min/km

3000 seconds ÷ 10 km = 300 s/km = 5:00 /km; speed 12 km/h.

Project half marathon

Entered run

distanceKm:10

hours:0

minutes:50

seconds:0

targetDistanceKm:21.0975

enduranceExponent:1.06

Pace (min/km)

About 1:50:19 projected (≈5:14 /km)

Riegel: 3000 × (21.0975/10)^1.06 ≈ 6619 seconds.

Use recent race data

Project from a race within a few weeks for more relevant estimates.

Frequently Asked Questions

Convert miles to kilometers first, or interpret pace as per km after conversion.

Still have questions about this calculation?

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Running Pace Formulas

No GPS smoothing or grade adjustment is embedded.

Formula

total seconds ÷ distance km

Pace

total seconds ÷ distance km

Speed

distance km ÷ (total seconds / 3600)

Riegel projection

T2 = T1 × (D2 / D1)^exponent

Scientific Background

Assumptions: even effort and comparable courses. Limitations: heat, hills, and fitness change real outcomes. CDC adult activity guidelines discuss aerobic training volume separately from race prediction.

Sources & review

Running Pace Calculator documents the references behind its formulas and assumptions. Always treat results as educational estimates, not personalized professional advice.

Last reviewed

July 22, 2026

Physical Activity Guidelines for Adults
Centers for Disease Control and Prevention (CDC)
https://www.cdc.gov/physical-activity-basics/guidelines/adults.html

See our methodology and corrections policy.