Race Time Predictor
Compare race-distance finish times with an entered power-law exponent or an exponent fitted to two recorded performances.
YOUR CALCULATION
Result
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Calculation steps
Work through one step at a time or reveal the complete calculation. The steps use your current inputs.
How to calculate
Scale finish time by a power of the distance ratio; alternatively identify that exponent from two different race distances and times.
T₂=T₁×(D₂/D₁)^b; fitted b=ln(T₂/T₁)/ln(D₂/D₁)
Worked example
A 25:00 result over 5 km with an entered exponent of 1.06 gives about 52:07.40 over 10 km. An exponent of 1 gives exactly 50:00, the constant-pace case.
Assumptions and input details
The editable 1.06 is a numerical scenario, not a universally validated fatigue coefficient or a claim about the exponent in Riegel’s original paper. Conditions, race preparation, course, weather and endurance differ; extrapolation across large distance ratios can be poor. A fitted exponent summarizes only the two supplied performances. No training targets or guaranteed result are inferred.
References: Primary research: endurance-coefficient comparisons and model limitations
Unit definitions
Unit selection is independent of language. Each selector contains only units for its physical quantity. Calculations use defined base units internally.
Choose from 23 length definitions, including explicitly labelled regional measures. Area conversions square the length factor; geometric volumes cube it.
Regional measures are not interchangeable merely because their names look similar. This is a documented selection, not a claim to include every historical unit.
NIST measurement tables · Japanese traditional units · Mainland China and Hong Kong unit distinctions
Using this calculator
Can I enter my own problem?
Yes. Replace the example values with your own inputs. The result, calculation steps, tables and applicable diagrams update from those inputs. Blank or invalid values clear the result; example values are never silently substituted for missing inputs.
Are the results exact?
Results use floating-point arithmetic and displayed rounding. Read the formula, assumptions and any stated data precision before interpreting the result.
Is my input uploaded?
The calculation runs in your browser. No account, file upload or external AI service is required. Inputs are not saved between page reloads.
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