The following calculator is based on the World Association of Veteran Athletes (WAVA) age-graded tables from 2006 (updated in 2010). The rational is the assumption that if you can run a 10K at 75% for your age and sex then you can probably run a 5K and a 15K at about 75% too. This calculator merely figures out your age-graded percentage for a specific race and applies that to a bunch of other distances...
Of course the correlation between a 5K and a Marathon isn't as meaningful as the correlation between a 10K and a 15K.
And a time on Pier to Peak or the State Street Mile doesn't correlate well with a flat race.
The idea for this calculator grew out of (separate) conversations with Rusty and Kornell.
The following graph shows the age related decline in speed for the selected race. These are the WAVA data which are based (loosely) on world record times for each age (and then smoothed).
The graph has been normalized so that when people are running their fastest that is considered a speed of 100%. The decline for men is shown with a blue line, the decline for women with a red line. The fainter red line compares women's speeds at various ages to the men's best speed (instead of the women's best speed).
The horizontal axis is in years. The WAVA data start at 5 years old and end at 99.
When I was 48 I ran a 10K race where the lead woman was .1 second ahead of me but my age graded percentage was .1% more than hers. That was the first time a woman beat me in a race with a lower age-graded-percentage than mine, and I wondered when does the cross-over happen?
The following graph allows you to fiddle with the WAVA data for given races by comparing men against women where the women's age is offset from the men by a certain amount (so men can be compared to younger (or older) women).
The graph has been normalized so that when men are running their fastest that is considered a speed of 100%. The decline for men is shown with a blue line, the decline for women with a red line.
The horizontal axis is in years with men marked in blue, and women in red (or, if the age offset is 0, then everyone is in purple).