From the founder
truefuels exists to help you be your best. It was built on a simple idea: stop fuelling being the thing that lets you down. I set out to simplify the process and simplify the products — to build a fuelling solution you could rely upon whatever the event. Energy gels fuel the work. Electrolytes keep the fluid environment right so that work is possible. CoreCtrl supports the cooling system that keeps you in control when the heat is on.

This calculator helps you put the right products together, in the right amounts, at the right time. It's not going to be perfect 100% of the time, but use it as a good guide — I built the logic on the latest scientific literature and my own experience. And always test your nutrition in training.

— Alistair Brownlee, co-founder, truefuels

truefuels

nutrition calculator

Science-driven fuelling from pre-start through 30 min before the finish. Validate in training.

confidence: medium

Inputs

Quick start

Monthly product plan

What you need for training + race day

Monthly training
Energy Gels (high salt)
3 sessions/wk × 2 gels
24
per month
Race day
4 gels
⚡Practise your race strategy at least 3 times before race day. This means 12 gels for practice runs alone.
Suggested order: 1× box of 40 gels — approx. £72/month
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This plan assumes you start race-ready — well hydrated, with good electrolyte balance and fully topped-up glycogen stores. Follow a proper pre-race nutrition strategy in the 24–48 hours before your event to ensure these levels are optimised.

When to fuel

Plan carbs, fluid, and sodium from pre-start through 30 minutes before the finish — little benefit from pushing intake in the final half-hour.

Products per hour

rounded to practical steps
40truefuels
HIGH SALT · 1g
40truefuels
LOW SALT · 0.25g
2gels / hour
≈ 2 truefuels gels per hour
Total needed3 gels
truefuels1.0
ELECTROLYTE SACHET
0sachets / hour
≈ 0 electrolyte sachets per hour
Total needed0 sachets
truefuels
BOTTLE
396mL / hour
≈ 0.8 bottles per hour
Total needed0.6 L

Total calculated requirement (targets)

CarbohydratesTotal: 108g
72g/h
≈ 2 truefuels gels per hour
Sodium (Salt)Total: 3g
2g/h
FluidTotal: 0.6 L
396mL/h
Plan ~396 mL/h (band 396–396) · ≈ 0.8 bottles/h mid-band

Bottle planner

Race nutrition timeline

When to take each product — based on your calculated rates (in-race fuel stops 30 min before finish).

💧 Water — 396 mL/h (sip gradually)
🟠 High salt gel — every 30 min (2/h)
-5'
30'
60'
🟣 Electrolyte sachet — every — min (0/h)
START
1h
FINISH
Total: 3 gelsTotal: 0 electrolyte sachetsWater: 0.6 L total
320 mLwaterWATER3 HIGH SALT GELS0 ELECTROLYTES

Each 500 mL bottle contains:

320 mL water
3 high salt gels — mix in or carry separately
0 electrolyte sachets — dissolve in water
Running / no-carry events
For events where it's not practical to carry water (e.g. marathon, half marathon), decant your gels into a small squeezable flask and pick up water at on-course aid stations.

Confidence

Plan confidence?Medium
~Sweat rateestimated
~Sweat sodiumestimated
✓Body weightmeasured
✓Durationmeasured
✓Temperature/humiditymeasured
  • CHO recommendation based on RPE, session type, and gut tolerance; fluid and salt are estimated—validate in training.

Safety note

This is an estimate based on the inputs provided. If sweat rate and sweat sodium are not measured, water and salt targets can be materially off. Validate in training and adjust for thirst, GI tolerance, and practical bottle access.