Transparency and trust
TriSplitCalc Methodology
Every serious calculator on TriSplitCalc should show what it calculates, what it assumes, and where the estimate can break.
Maintained and reviewed
Maintained by
M Imtinan Farooq
Last updated
July 13, 2026
Scope
Planning calculators, not coaching or medical advice
Finish time and splits
Formulas
- Swim split = swim distance / 100 x swim pace per 100m
- Bike split = bike distance / average bike speed
- Run split = run distance x run pace
- Total finish time = swim + T1 + bike + T2 + run
Limitation
These formulas assume the entered paces are realistic for race conditions. Open water, terrain, wind, heat, crowding, nutrition, and fatigue can change the result.
Cutoff buffer
Formulas
- Swim buffer = official swim cutoff - wave offset - swim split
- Bike buffer = official cumulative bike cutoff - wave offset - swim - T1 - bike
- Finish buffer = official finish cutoff - wave offset - total finish time
Limitation
Cutoff defaults are planning presets only. Official athlete guides and race-day instructions control the real cutoff rules.
FTP bike split
Formulas
- Target watts = FTP x intensity factor
- Watts per kg = target watts / body mass
- Bike TSS = bike hours x intensity factor squared x 100
- Estimated speed = broad W/kg speed estimate x course modifier x setup modifier
Limitation
This is not a course-file physics model. It does not model wind, CdA, rolling resistance, altitude, gradient-by-gradient pacing, or road surface directly.
Run off the bike
Formulas
- Adjusted run pace = standalone pace + distance penalty + bike-effort penalty + heat penalty + nutrition penalty
- Run split = adjusted pace x run distance
Limitation
The penalty is a durability planning estimate. Brick workouts, race history, and long-course experience should calibrate it.
Heat adjustment
Formulas
- Adjusted pace = base pace + temperature penalty + humidity penalty + acclimation adjustment
- Heat-adjusted split = adjusted pace x run distance
Limitation
This is a pacing guardrail, not medical advice. Hot races require cooling, hydration, and race medical guidance.
Course adjustment
Formulas
- Adjusted swim pace = neutral swim pace x swim condition modifier x wetsuit modifier
- Adjusted bike speed = neutral bike speed x bike course modifier
- Adjusted run pace = neutral run pace x run course modifier
- Course buffer = adjusted race-day estimate - neutral estimate
Limitation
Course modifiers are broad planning categories. They do not replace course files, official athlete guides, weather forecasts, or segment-by-segment modeling.
Aid-station nutrition
Formulas
- Bike carbs = bike hours x carb target per hour
- Run carbs = run hours x carb target per hour
- Bottle count = bike carbs / bottle carbs, rounded up
- Gel count = required carbs / gel carbs, rounded up
- Sodium total = bike + run hours x sodium target per hour
Limitation
Carb, fluid, and sodium tolerance varies by athlete. Practice in training before using any race-day plan.
Validation examples
Formulas
- Example outputs are calculated from the same swim, bike, run, and transition formulas as the calculator pages
- Realism notes compare the output against the scenario, not against a guaranteed athlete result
- Training checks identify what should be proven before trusting the plan
Limitation
Examples are archetypes for sanity-checking. They are not personalized coaching, medical advice, or proof that a target is appropriate for every athlete.
Source library
Build the plan from the right tool
Trust and methodology
How this page should be used
Last updated
July 13, 2026
Maintained by
M Imtinan Farooq
Status
Planning estimate, not a race guarantee
Formula summary
Finish time = swim + T1 + bike + T2 + run, with related tools for risk checks.
Key assumptions
Entered paces, distances, transitions, and condition choices are race-realistic.
Limitations
Weather, course profile, water conditions, equipment, and execution can change results.