StrideForever · free running tools

Know your
pace. Master
your race.

Six fast, accurate running calculators — pace, race predictions, splits, training zones, treadmill conversion and WMA age grading. No sign-up, no fluff.

StrideForever is a set of free calculators and plain-language guides for runners. Work out your pace, predict your race times, plan your splits and understand the training science behind the numbers — every tool works in km and miles, in English, Hungarian and German.

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Running Pace Calculator

Calculate your running pace per km and per mile from any distance and time. Free, instant pace and speed calculator.

Race Time Predictor

Predict your race finish time for 5K, 10K, half and full marathon from a recent result using the Riegel formula.

Age Grading Calculator

Calculate your WMA age-graded percentage and age-graded time for 5K, 10K, half marathon and marathon by age and sex.

Built for runners, not for sign-up forms.

01

Genuinely free

No account, no paywall, no trial. Supported by ads — never by your wallet.

02

Accurate by design

Age grading uses the official WMA tables; race predictions use the proven Riegel formula.

03

Fast & private

Every calculation runs in your browser. Nothing to install, nothing stored.

Guides

Learn the numbers

What Is Age Grading? A Runner’s Guide to Age-Graded Scores

How age-graded percentages let a 25-year-old and a 70-year-old compare performances on a level playing field — and what your score actually means.

How to Calculate Your Running Pace (and Actually Use It)

Pace is the number every runner lives by. Here’s how to calculate it, convert it to speed, and turn it into race splits and training zones.

Race Time Prediction Explained: Using the Riegel Formula

How a single recent result can predict your 5K, 10K, half or marathon time — and why the Riegel formula’s 1.06 fatigue factor matters.

Even vs Negative Splits: How to Pace Your Race

The difference between even, negative and positive splits — and how to plan the splits that stop you blowing up in the second half.

Ready to run the numbers?

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New to the numbers? Read the guides