Running calculators

Seven tools that cover the questions runners ask most. Every one shows its formula and its limits.

Pace, time or distance from the other two.

One race in, predicted times from the mile to the marathon.

Easy, marathon, threshold and interval paces from a recent race.

Five zones from your max heart rate, using the Norwegian model.

Even or negative splits for any goal time.

Speed and incline converted to outdoor pace.

How much to slow down in heat and humidity.