Triathlon Split Calculator — Rex's Toolbox

Rex says

Same equations the textbooks use — just way less awkward. Pop in your stats and I'll tell you what the number actually means for you.

Try a scenario

Click to load — tweak from there.

Inputs

Swim distance(m)

Swim pace per 100 m(sec)

Bike distance(mi)

Bike speed(mph)

Run distance(mi)

Run pace(min/mi)

T1(min)

T2(min)

Result

Projected finish time

346

Swim split

Bike split

187

Run split

118

Total hours

5.77

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How to use this

1Enter swim distance (m).
2Enter swim pace per 100 m (sec).
3Enter bike distance (mi).
4Enter bike speed (mph).
5Enter run distance (mi).
6Enter run pace (min/mi).
7Enter t1 (min).
8Enter t2 (min).
9Read your projected finish time on the right — it updates as you type.
10Hit Share to keep the scenario or send it to someone.

About this calculator

Enter your paces for each leg plus transition estimates and get the full race timeline — including what each discipline contributes as a share of the day.

FormulaTotal = swim + T1 + bike + T2 + run.

Worked example

Using the values the calculator loads with:

Inputs

Swim distance: 1900 m
Swim pace per 100 m: 110 sec
Bike distance: 56 mi
Bike speed: 18 mph
Run distance: 13.1 mi
Run pace: 9 min/mi
T1: 4 min
T2: 3 min

Results

Projected finish time: 346
Swim split: 35
Bike split: 187
Run split: 118
Total hours: 5.77

What each field means

Inputs

Swim distance (m): The swim distance used in the calculation, measured in m. Starts at 1900 m so you have a working example on load.
Swim pace per 100 m (sec): The swim pace per 100 m used in the calculation, measured in sec. Starts at 110 sec so you have a working example on load.
Bike distance (mi): The bike distance used in the calculation, measured in mi. Starts at 56 mi so you have a working example on load.
Bike speed (mph): The bike speed used in the calculation, measured in mph. Starts at 18 mph so you have a working example on load.
Run distance (mi): The run distance used in the calculation, measured in mi. Starts at 13.1 mi so you have a working example on load.
Run pace (min/mi): The run pace used in the calculation, measured in min/mi. Starts at 9 min/mi so you have a working example on load.
T1 (min): The t1 used in the calculation, measured in min. Starts at 4 min so you have a working example on load.
T2 (min): The t2 used in the calculation, measured in min. Starts at 3 min so you have a working example on load.

Results

Projected finish time: Returned as a length of time and shown as the headline result. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
Swim split: Returned as a length of time. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
Bike split: Returned as a length of time. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
Run split: Returned as a length of time. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
Total hours: Returned as a decimal number. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.

FAQ

Defaults look like a 70.3?

They are — 1.9 km swim, 56 mi bike, 13.1 mi run. Change the distances for sprint, Olympic, or full.

How much do transitions matter?

5–8 minutes across both for age-groupers. It's the cheapest time you'll ever find, and it costs zero fitness.

Accuracy and limitations

Population formulas describe averages; individual bodies vary, especially at the extremes of height, age, or muscle mass.
Results do not account for medical conditions, medication, or pregnancy.
Use this as a directional reference, not a diagnosis — talk to a clinician before acting on it.

Cite this calculator

Writing about this topic? Grab a citation — every link helps keep these tools free.

APA

RevenueLab. (2026). Triathlon Split & Finish Time Calculator. Retrieved from https://www.revenuelab.fyi/toolbox/triathlon-split

HTML

<p>Source: <a href="https://www.revenuelab.fyi/toolbox/triathlon-split" target="_blank" rel="noopener">Triathlon Split & Finish Time Calculator — RevenueLab</a> (2026).</p>

Markdown

Source: [Triathlon Split & Finish Time Calculator — RevenueLab](https://www.revenuelab.fyi/toolbox/triathlon-split) (2026).