Duathlon Time Calculator
Duathlon finish time, longest leg, and pace from splits.
What it does
Duathlon swaps the swim for second run legs. Run, bike, run plus two transitions sum to the finish line.
The tool above adds the legs. A sprint at 6 min run pace and 2.5 min bike pace with 4 min of transitions totals 1 h 39 min, led by the 50 min bike leg at 3.6 min per km overall.
Formats set the distances. Sprint runs 5/20/2.5 km, standard doubles to 10/40/5, and super sprint shortens the first run.
The bike usually rules. Twenty to forty kilometers at two to three minutes each dominate totals, so bike fitness decides most finishes.
Transitions count free speed. Four practiced minutes beat eight fumbling ones with no extra fitness.
How to use
- Pick race: sprint suits the default.
- Enter run pace per km.
- Enter bike pace per km.
- Enter transitions total.
- Read finish time first.
- Read longest leg and average pace.
Formula
- race
- Sprint, standard, or super sprint race.
- run pace
- Run minutes per km.
- bike pace
- Bike minutes per km.
- transitions
- Both transitions combined.
Distances are World Triathlon duathlon formats in km. Paces are minutes per km for run and bike separately.
Worked example
Example: sprint duathlon splits
Defaults: sprint duathlon at 6 min run and 2.5 min bike pace with 4 min transitions. These are also the default values, so the page opens on this answer.
- Race: sprint 5 km run, 20 km bike, 2.5 km run.
- Run pace: 6 min per km.
- Bike pace: 2.5 min per km.
- Legs: 5 x 6 = 30 min, 20 x 2.5 = 50 min, 2.5 x 6 = 15 min.
- Total: 30 + 50 + 15 + 4 transitions = 1 h 39 min.
- Longest: 50 min bike leg. Pace: 99 / 27.5 = 3.6 min per km.
- Tool shows 1 h 39 min, 50 min longest leg, 3.6 min per km.
Reference table
| Race | Format | Total km |
|---|---|---|
| Super sprint | 2.5/20/2.5 | 25 km |
| Sprint | 5/20/2.5 | 27.5 km |
| Standard | 10/40/5 | 55 km |
Limits
- Split math only, not coaching.
- Course hills and wind shift races.
- Draft rules change bike paces.
- Gear failures need backup plans.
Common mistakes
- Forgetting transitions in totals.
- Sprint pace for standard distance.
- First run too hot, second run walking.
- Untested shoes on race day.
- Skipping brick workouts.
Try it yourself
Quick checks. Answers sit tucked under each question.
Standard at 6 run, 2.5 bike, 6 transitions?
Legs are 10 x 6 = 60, 40 x 2.5 = 100, 5 x 6 = 30. Total is 60 + 100 + 30 + 6 = 196 min, or 3 h 16 min.
Sprint at 5 run, 2 bike, 3 transitions?
Legs are 5 x 5 = 25, 20 x 2 = 40, 2.5 x 5 = 12.5. Total is 25 + 40 + 12.5 + 3 = 80.5, or 1 h 21 min after rounding (80.5 rounds to 81).
Questions
Total finish time?
Add each leg plus transitions. Here 30 + 50 + 15 + 4 = 99 min, or 1 h 39 min.
Race distances?
Sprint 5/20/2.5, standard 10/40/5, super sprint 2.5/20/2.5 in km.
Longest leg?
Take the max of the three legs. Here the 50 min bike leg.
Average pace?
Divide total by race km. Here 99 / 27.5 = 3.6 min per km.
Course effects?
Yes. Hills, wind, and heat move real races past flat math.
Does this pace the race?
No. Pacing advice needs coaching.