Endurance training,
reduced to math.
A focused suite of 13 calculators for runners and cyclists. No accounts. No wearables. No data harvesting. Open a calculator, get an answer, close the tab.
13 tools.
Pick one. Get an answer.
Inputs stay in your browser. No accounts. No tracking. Runners and cyclists, nutrition and performance.
Daily fuel needs
Calories you actually need today — BMR, lifestyle activity, and the energy cost of training.
Formula & limits
BMR — Mifflin–St Jeor (1990): male 10W + 6.25H − 5A + 5, female 10W + 6.25H − 5A − 161.
NEAT = BMR × (lifestyle factor − 1). Training kcal = MET × kg × hours. Run easy ~9 MET, tempo ~11, intervals ~13. Cycle easy ~6, tempo ~8, threshold+ ~11.
Macro split: endurance default 55% carbs / 20% protein / 25% fat.
Estimates. Individual variance is ±10–15%.
During-workout carbs
Grams of carbohydrate per hour — scaled by duration, intensity, and gut training.
Formula & limits
< 60 min no carbs (mouth rinse optional) 60–150 min 30–60 g/hr (glucose alone) 150–180 min 60–75 g/hr (glucose + fructose ~2:1) > 180 min 75–90 g/hr (multiple transportable) Race / trained 90–120 g/hr (advanced gut training)
Practice race-day fueling in training. The upper end requires weeks of gut adaptation.
Race time predictor
One known race time. Predicted times across every common distance, using Riegel's formula.
Formula & limits
T₂ = T₁ × (D₂ / D₁) ^ 1.06 (Riegel, 1981)
Most accurate within ~3× of the known distance. Marathon-specific endurance (long-run base, fueling) isn't captured.
VDOT training paces
Jack Daniels' training paces — Easy, Marathon, Threshold, Interval, Repetition — from a recent race.
Formula & limits
VO₂ = −4.6 + 0.182258·v + 0.000104·v² (v in m/min)
%max = 0.8 + 0.1894393·e^(−0.012778·t)
+ 0.2989558·e^(−0.1932605·t) (t in min)
VDOT = VO₂ / %max
Zone %VDOT: E 70 · M 84 · T 88 · I 97 · R 105
FTP power zones
Coggan's 7-zone power breakdown from your Functional Threshold Power.
Formula & limits
Z1 Active Recovery < 55% FTP Z2 Endurance 56–75% Z3 Tempo 76–90% Z4 Threshold 91–105% Z5 VO₂ max 106–120% Z6 Anaerobic 121–150% Z7 Neuromuscular > 150%
FTP ≈ highest power sustained for ~1 hour. Estimate via 20-min test × 0.95.
W/kg power-to-weight
The number that matters on every climb. FTP ÷ weight, mapped to rider category.
Not built yet.
This calculator is part of the v1 roadmap and will land here once the formula and chart are dialled in. The page exists so the route works and so you know it's coming.
In the meantime, six calculators are Live and ready to use.
← Back to all calculatorsSports nutrition,
cut to the bone.
Short articles on the nutrition questions endurance athletes actually ask. Coming soon.
First articles drop alongside v1.0. Calculators ship first.
About t90.club
A clean, free toolbox of endurance calculators — built because every existing one wants your email first.
What this is
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A solo builder making the tool I wished existed when I was training.
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