Triathlon calculator — Sprint to Ironman.
Free triathlon calculator and Ironman time calculator. Pick a distance — Sprint, Olympic, 70.3 / medio Ironman or Full Ironman — plug in your swim, bike and run pacing, and we'll estimate your splits and total finish time.
Ironman & 70.3 Time Predictor: Realistic Forecasting
Why most long-course predictions are wildly optimistic — and the inputs that actually matter.
The Taper Myth
Why most age-group triathletes blow the taper — and how to enter race week sharp.
Heart Rate vs Power vs Pace
Which metric should anchor each leg of your race? Use this with the time predictor.
Jack Daniels VDOT: The Complete Guide
Translate any race into prescription-grade training paces with the most useful number in distance running.
VDOT calculator
Jack Daniels race predictor for runners — translate any race into all 5 training paces (Easy, Marathon, Threshold, Interval, Repetition).
Ironman time predictor
Dedicated full Ironman calculator with bike-fade and run-fade modeling for IM distance.
Half Ironman (70.3) predictor
70.3-specific finish-time predictor with transitions baked in — metric or imperial.
AI race-day nutrition plan
Personal carbs/hr, sodium and fluids plan — the fueling side of any IM/70.3 prediction.
Carb loading calculator
Race-week carbs to bank for a 70.3 or full Ironman without GI distress.
Sweat & sodium calculator
Bottle-by-bottle hydration plan that protects the predicted run split.
Triathlon coach
1:1 coaching across sprint, Olympic, 70.3 and full IRONMAN.
IRONMAN 70.3 coach
16–24 week 70.3 builds with course-specific brick work.
Marathon coach
Turn the predicted split into a real PR — pacing, fueling, taper.
Online triathlon coach
Fully remote 1:1 coaching for triathletes worldwide.
Want a 70.3 or full Ironman build, not just a finish-time guess?
Predictions only matter if the swim, bike and run all hold up on race day. Coaching turns these splits into a periodized 16–24 week plan with course-specific brick work and fueling.
Boston-based · Trilingual EN/PT/ES · RRCA · USAT · TrainingPeaks L2 · 12× Boston qualifier
Frequently asked
How accurate is this triathlon time calculator?
It uses your real swim, bike and run paces (no fitness assumptions) plus realistic transition defaults, so for Sprint and Olympic it's typically within 2–3%. For 70.3 and Ironman, accuracy depends on whether you can actually hold those splits for 4–12 hours — most athletes overestimate sustainable bike power and run pace by 5–10% at the long distances.
What's a realistic Ironman finish time for a first-timer?
Most first-time Ironman finishers come in between 12:30 and 14:30. Aim for: 1:15–1:45 swim (1.5–2.3 min/100m), 6:00–7:00 bike (26–30 km/h average), 4:30–5:30 run (6:25–7:45 min/km) plus 10–15 min of transitions. Sub-12 requires sub-7 bike + sub-4:30 run consistently.
Should I plan to ride my FTP on race day?
No. For 70.3 target 75–82% of FTP (intensity factor 0.78–0.85). For full Ironman target 65–75% of FTP (IF 0.68–0.78). Going harder almost always blows up the run — fast bike splits cost more time than they save when you walk the marathon.
How do transitions affect my finish time?
T1 (swim→bike) typically takes 2–4 min for age-groupers, T2 (bike→run) 1–3 min. Across an Ironman that's 4–7 minutes — meaningful but tiny vs the bike+run pacing decision. Beginners often lose 5–10 minutes here; practicing transitions is the cheapest time you'll find.
Why is my predicted Ironman run pace so much slower than my open marathon?
After 180km on the bike, most athletes run 25–45 seconds per km slower than their fresh standalone marathon pace. The calculator already assumes that fade — if you enter your standalone marathon pace, your real Ironman split will be longer. Use a brick-workout pace as the input for the most realistic forecast.