How to use it
- Choose the Race distance; pick Custom to type your own swim, bike and run distances.
- Choose Kilometres or Miles under Distances and speeds in, then type your Swim pace per 100 m, Bike speed and Run pace.
- Enter Transition 1 and Transition 2 if you know them. Leave them empty to count them as zero.
- Read the Total time, then open Split times for the time and the elapsed time at each part.
How each part is calculated
The swim time is the distance in metres divided by 100 and multiplied by your pace per 100 m. The bike time is the distance divided by your average speed. The run time is the distance multiplied by your pace per km. The transitions are added as you type them, and the total is the sum of the five parts.
Swim = distance (m) ÷ 100 × pace per 100 m
Bike = distance (km) ÷ speed (km/h) × 3,600
Run = distance (km) × pace per km
Total = swim + transition 1 + bike + transition 2 + run- Miles are converted with 1 mile = 1.609344 km.
- Standard distances: sprint 750 m, 20 km and 5 km; Olympic 1.5 km, 40 km and 10 km; half (70.3) 1.9 km, 90 km and 21.1 km; full (140.6) 3.9 km, 180.2 km and 42.2 km.
Standard distances and what the tool leaves out
The sprint and Olympic distances are the ones World Triathlon gives on its elite page for those formats. The 70.3 and 140.6 distances are the ones in the Wikipedia article on the IRONMAN races, which give them in miles and kilometres. Other events use other distances: check your race guide, and choose Custom for them.
- Course climbs, wind, currents, wetsuit rules and penalties.
- Changes of pace during a race. The tool uses one average pace for each part, and a real race varies with the hills and the other athletes.
Worked example: Olympic distance at 1:50 per 100 m, 30 km/h and 5:00 per km
The swim is 1,500 m: 15 × 110 seconds = 1,650 seconds, or 27:30. The bike is 40 km at 30 km/h: 40 ÷ 30 × 3,600 = 4,800 seconds, or 1:20:00. The run is 10 km at 5:00 per km: 10 × 300 = 3,000 seconds, or 50:00.
With transitions of 1:00 and 0:45, the total is 1,650 + 60 + 4,800 + 45 + 3,000 = 9,555 seconds, which is 2:39:15.
| Part | Distance | Time | Elapsed time |
|---|---|---|---|
| Swim | 1,500 m | 27:30 | 27:30 |
| Transition 1 | 1:00 | 28:30 | |
| Bike | 40 km | 1:20:00 | 1:48:30 |
| Transition 2 | 0:45 | 1:49:15 | |
| Run | 10 km | 50:00 | 2:39:15 |
Frequently asked questions
What are the 70.3 and 140.6 races?
They are the half and full IRONMAN distances. The 70.3 is 1.2 miles of swimming, 56 miles of cycling and 13.1 miles of running; the 140.6 is 2.4 miles, 112 miles and 26.2 miles. The number is the total distance in miles.
Why are the transitions counted separately?
Changing from swim to bike and from bike to run takes real time, and it is part of your finish time. Entering it separately shows how much a faster transition would save.
Can I use miles for the bike and the run?
Yes. Choose Miles under Distances and speeds in, then enter the bike speed in mph and the run pace per mile. The swim pace stays per 100 m, because pools and swim races are measured in metres or yards.
How accurate is the prediction?
It is an estimate that assumes a steady pace in each part. Wind, heat, hills and how you pace yourself change the real time, so use the result for planning and not as a promise.
Do I need to know my exact transition times?
No. Leave them empty to count them as zero, or type an estimate. Because the transitions are part of the total, a realistic estimate is better than zero.
Does the tool keep my times?
No. Everything is worked out in your browser, and nothing you enter is sent to us or saved on your device.
Sources
- World Triathlon: Elite (sprint 750 m swim, 20 km bike, 5 km run; standard/Olympic 1.5 km swim, 40 km bike, 10 km run)
- Wikipedia: Ironman Triathlon (70.3: 1.9 km, 90 km, 21.1 km; 140.6: 3.9 km, 180.2 km, 42.2 km; the miles are given too)
Figures and text last checked on Tuesday, November 10, 2026.