Free running calculators
The calculations Endu uses to build your plan, free to use: MAS and MAS test, training paces, race time prediction, split times, pace/speed conversion, effort kilometres, heart rate zones, swim CSS, cycling FTP, triathlon times and race fuelling.
Free, no sign-up. Everything is computed in your browser: nothing you type here is sent anywhere.
MAS calculator
Work out your MAS from a race time or a 6-minute test and get your five training paces. Method explained, no sign-up.
MAS test: protocols and calculator
How to run a MAS test on your own, with or without a track: 6 minutes all out, Cooper test, 1,500 m. The calculator gives your MAS and paces.
Training pace calculator
Your five paces in min/km from your MAS or a race time: easy, marathon, threshold, intervals, repetitions — each with its use.
Race time predictor
From a single race time, estimate your times on every distance from 5 km to 100 km, pace included. No exponent formula.
Effort-kilometre calculator
Convert distance and elevation into flat kilometres, with the terrain coefficient and a time estimate. To compare a trail with a road race.
Heart rate zone calculator
Your five heart rate zones from the best data you have: heart rate reserve, threshold HR or max HR, using the Tanaka formula.
CSS calculator (critical swim speed)
Work out your CSS from the 400 m and 200 m tests and get your six swim paces in min/100 m. For triathlon and swimrun.
FTP and power zone calculator
Work out your FTP from a 20-minute test and get your six Coggan power zones, plus your watts per kilo.
Triathlon time calculator
Estimate your total time and three splits, transitions and bike fatigue included, from super sprint (XS) to Ironman.
Race fuelling calculator
How much carbohydrate per hour, at what rhythm to take it, and the list of what to buy and carry — computed with your own products, from a 10K to an ultra.
Split times calculator
Your pace per kilometre and your split times, every km or every 5 km, for a 10K, a half or a marathon, with your pace and speed.
Pace / speed converter
Convert a pace in min/km into a speed in km/h, and back. With a table from 3:00 to 8:00 /km and the matching times over 5K, 10K, half and full marathon.
Long-term goal: your roadmap to UTMB, an Ironman or a marathon
Pick your dream race and the year: Endu works out the steps, one category at a time, suggests races for each and counts the Running Stones for UTMB.
Already have a plan?
Written by ChatGPT, a coach or a magazine: have it checked against training science, for free.
Now the plan that goes with it
These numbers are exactly the ones Endu uses to build a full preparation: phases, volume, detailed sessions, exported to your watch. 14-day trial, cancel any time.
Create my plan