Index
Running calculators
Six tools, each with the formula behind it published on the page and an honest account of where the model breaks down.
Pace, speed and unit conversion
Pace from distance and time, every standard split, plus mile/kilometre and speed conversion.
02Race time prediction
Riegel across all distances, equivalent times, and the half-to-full question.
03Training paces
Five VDOT-derived zones, plus Yasso 800s and why it works better than it should.
04Heart rate zones
Threshold, Karvonen and percentage methods, ranked, plus target heart rate.
05Treadmill, incline and finish projection
What a grade is really costing you, and where your current pace ends up.
06Sweat rate and fluid planning
Measured hourly loss turned into a per-aid-station drinking plan.
Which one do you need?
You have a finish time and want your pace. Start with the pace calculator. It also produces the split sheet for every standard checkpoint, which is the part most runners actually use.
You have a recent race and want to know what you are capable of at another distance. The race time predictor uses Riegel’s fatigue exponent, and includes a method for calibrating that exponent to your own history rather than accepting the default.
You have a race result and want to know how to train. The training pace calculator converts it into five zones using the VDOT equations.
You want to control intensity when pace is unreliable. Heat, hills and fatigue all break the link between pace and effort. The heart rate zone calculator offers three anchoring methods and explains which to trust.
You train indoors or on hills. The grade-adjusted pace calculator converts belt speed and incline into the flat-road pace of equivalent oxygen cost.
You are racing long, or racing warm. Measure your losses with the sweat rate calculator before the day rather than during it.