Marathon Pace Calculator

Give this calculator a race distance and the time you want to run, and it prints the split you need at every marker: elapsed time and the leg between markers at every 5 km, every mile, every 5 miles or each quarter of the race. A negative split percentage tilts the plan so the second half is run that much faster than the first, and the first and second half paces are shown separately. The second mode predicts an equivalent time at another distance from a race you have already run, using Riegel's 1.06 exponent. For the plain conversion between pace and finish time, the pace calculator is the shorter route; this one exists for the table you pin to your wrist. A predicted marathon from a short race is a ceiling rather than a promise, because the formula assumes your training already covers the longer distance.