Champagne Running / Race-time predictor
Your next race.
A range of outcomes.
Start with a race you’ve run. Explore what it suggests about another distance.
Estimated marathon finish
Loading the outcomes…
Middle 80% of outcomes
—A range from real runners’ personal bests.
01 / The bigger picture
A range of outcomes
Real runners with a similar personal best at your starting distance.
These are recorded best times, not a promise for race day. Preparation for your target distance matters.
02 / Different approaches
Compare the predictions
Choose a method to see its estimate above.
The range comes from similar runners. Differences between formulas are not a range of uncertainty.
03 / Your finish line
A time in mind?
See where your goal sits among similar runners.
04 / Keep exploring
At other distances
A little context
Behind the numbers
Useful estimates, with room for race day.
Where does the range come from?
The middle estimate is the median personal best among runners with a similar PB at your starting distance. The range covers the middle 80% of their target-distance best times. Each runner counts once.
We match PBs within ±2.5% of the nearest supported lookup time. The comparisons do not account for training, course, weather or when the races were run. Goal percentages describe this group, rather than a calibrated personal probability.
What do the other methods mean?
Original research uses the archived median and smoothed (LOWESS) relationships from the Poultry project. Riegel uses the standard distance-scaling exponent of 1.06. Daniels / VDOT finds an equivalent performance at the same fitness score.
Riegel and VDOT often agree closely for faster runners; that agreement does not independently validate a forecast. World Athletics finds equal-point performances in the original men’s and women’s scoring tables. The tables’ edition is unverified and is not the current 2025 edition. Scoring equivalence is not an individual forecast.
A selected formula changes the headline estimate. The observed range and goal share always remain based on similar runners.
Why are some estimates unavailable?
Some distances and finish times have too few comparable runners, or fall outside the original tables. We leave those results blank rather than extrapolate. A formula may still provide a single estimate when there is no supported range.
Data, privacy and source notes
Your inputs stay in this browser. The site downloads aggregate counts and percentiles, not runner names or IDs. Recorded personal bests can come from different race dates.
The original curves were saved in November 2023. The similar-runner groups were rebuilt separately from the same results archive and do not reproduce every original cleaning step. The half-marathon and marathon formulas use 21.0975 km and 42.195 km; archived research retains its original rounded distance categories.
Vickers & Vertosick (2016) · Official V.O2 calculator · World Athletics table update
Daniels & Gilbert, Oxygen Power (1979). Riegel, Athletic Records and Human Endurance (1981).