HesapHanem

Cameron Race Time Predictor Calculator

Enter a known distance, time, and target distance to predict your race time.

How it is calculated

The engine applies Dave Cameron's model: T₂ = T₁ × (D₂ / D₁) × a(D₁) / a(D₂), where a(D) = 13.49681 − 0.000030363·D + 835.7114 / D0.7905. D₁ and D₂ are the known and target distances in metres, and T₁ is your known time in seconds. The first part, T₁ × D₂ / D₁, is the simple proportional scale-up. The correction a(D₁) / a(D₂) is above 1 when the target is longer, which adds time because pace slows with distance, and below 1 when the target is shorter. The tool shows the predicted time as h:mm:ss.ss, the same time in seconds, and the average pace in minutes per kilometre. All three inputs must be above zero.

Worked example

You ran 5000 m in 1500 s (25:00) and want a 10,000 m forecast. Straight proportion gives 1500 × 2 = 3000 s. The correction term is a(5000) / a(10000) = 14.3404 / 13.7687 = 1.0415. So T₂ = 3000 × 1.0415 = 3,124.6 s, which the tool shows as 0:52:04.58. The pace is 3124.6 / 10 km / 60 = 5.21 min/km, compared with 5.00 min/km for the 5K. The 10K is therefore predicted about two minutes slower than doubling the 5K time.

Try this example →

Common mistakes

  • Entering distances in kilometres. The fields are metres, so a 5K is 5000; typing 5 and 10 for a 5K and a 10K makes the tool see a 5-metre and a 10-metre sprint, and the output is nonsense (a pace of 8,317.63 min/km).
  • Entering the known time in minutes or as 25:00. The time must be in seconds, 1500; a clock format cannot be read.
  • Using a race that was not a hard effort. The model assumes the known time was a good, evenly paced result; a training run will predict a time that is too slow.
  • Predicting a very different distance and trusting it. A 5K time says little about a marathon, since long-distance training and fuelling decide that race. Use a nearer distance when you have one.
  • Expecting the same answer as the Riegel formula or the formula shown elsewhere. Different models weight the slowdown differently, so the predicted times for the same input will not match exactly.

About this calculator

The Cameron formula, developed by running statistician Dave Cameron in the 1990s, predicts a runner's finish time at one distance from a known result at another using a slightly non-linear model rather than a simple proportional scale-up: T2 = T1 × (D2/D1) × a(D1) / a(D2), where a(D) = 13.49681 − 0.000030363 × D + 835.7114 / D^0.7905 and distances are in metres. The correction term a(D) accounts for the fact that pace naturally slows as distance increases, making it more accurate than a flat multiplier across widely different race distances like a 5K to a marathon.

This calculator takes a known race distance and time along with a target distance and returns the predicted finish time. Runners setting a goal pace for an upcoming race and coaches building training plans around realistic time targets use it — alongside similar formulas like Riegel's — to translate recent race fitness into an expectation for a different distance, while acknowledging that specific endurance and training for the target distance still matter.

Was this helpful?

You can pick up to 3 reactions.

Comments (1)

  • Editorial team

    The pace line is shown in decimal minutes, not minutes and seconds. For the 25:00 5K, the 10K forecast of 3,124.6 s reads 5.21 min/km, which is 5:12 per kilometre, not 5:21. Multiply the part after the decimal point by 60 before comparing with your watch, or divide the predicted seconds by the distance in kilometres. Which target distance do you most often forecast, and how close did the last prediction land?

Popular calculators

Loan Calculator

Monthly payment, total interest and full amortization schedule.

Percentage Calculator

Percent change, percent of, and ratio calculations.

Discount Calculator

Calculate final price, savings, and discount amount.

BMI Calculator

Body mass index from height and weight (metric or imperial).

Age Calculator

Compute your exact age in years, months and days from a birth date.

Compound Interest Calculator

Calculate the final amount and interest earned with compounding.

All Calculators