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Race Fuel Cost Calculator
Should you buy gels, make your own mix, or use both? Pick a race preset or set your own session, and get a gram-accurate recipe, its cost per gram of carbohydrate, and what a full training block would save you.
Default for this duration: 60 g/h
Gentler on an untrained gut and less sweet — a good starting point.
Cheapest; fine for most mixes.
Your recipe — per bottle
500 ml bottle — drink one per hour
- 40 g maltodextrin (≈ 11.4 tsp)
- 20 g fructose (≈ 5 tsp)
- 1.65 g table salt (≈ 0.28 tsp · 650 mg sodium)
- 500 ml water
Grams first — teaspoons are rough. A basic kitchen scale (under €10) makes this repeatable.
Estimated gut-load: Amber — concentrated
12 g carbs per 100 ml. Sip gradually; test carefully in training first. This is an estimate from concentration, ingredient type and sodium — not a lab osmolality test.
- Carbs delivered: 60 g/hour · 240 g total over 4 h
- Servings for the session: 4
- Cost per serving: €0.38
- Cost per gram of carb: €0.0064 (≈ €0.38 per 60 g)
- Whole session DIY: €1.53 vs gels ≈ €18.00 (10 × €1.80)
Training-block savings estimate
Edit ingredient prices (€/kg) & gel reference
Set your local prices and currency — the defaults are only rough EU starting points.
Your inputs are encoded in the URL — send it to a training partner.
Every output here is a training-tested starting point, not a prescription: start at the lower end, test on easy long sessions, and never try anything new on race day.
Why this formula?
Maltodextrin is a glucose polymer: it carries a lot of carbohydrate with less sweetness and fewer osmotically-active particles than straight sugar, which is why a malto-heavy mix can deliver more carb at a lower estimated gut cost. Fructose is absorbed through a separate intestinal transporter, so a glucose+fructose mix raises how much you can take in per hour. Sodium replaces some of what you sweat out, and the water is what actually carries it all in.
What could go wrong?
GI upset from too much too soon; a mix that is too concentrated for your gut on the day; more sodium than you need; caffeine sensitivity if you add it on top; or not drinking enough plain water alongside a syrup. Heat and race-day nerves make all of these more likely — which is why everything here starts lower than the maximums.
How to test it
Start below your target carbs per hour. Try the mix on easy long sessions first, log how your stomach felt, and only then build towards race intake. Adjust for hot days. Never race on a recipe you have not trained with.
Commercial gels still have a role
DIY is best for
Regular training, long runs, cost control, bottle-based fuelling, and custom sodium or carb targets.
Commercial gels are best for
Race-day convenience, travel, aid-station simplicity, measured caffeine doses, and a known texture and tolerance with no mixing.
About the gut-load estimate
This is an estimate, not a lab osmolality test. The calculator uses carbohydrate concentration, ingredient type and sodium level to flag whether your mix is likely to behave like a normal drink, a concentrated syrup, or a gel that should be chased with water. Real-world osmolality depends on things a consumer calculator cannot know precisely — maltodextrin chain length, exact dissociation, and how accurately you measure and mix.
Worth knowing before you rely on any of this: if you have diabetes or glucose-control issues, kidney disease, high blood pressure or a sodium-restricted diet, caffeine sensitivity or a heart-rhythm condition, a history of GI distress, or relevant allergies and intolerances, treat these numbers as a conversation starter with a professional — not a plan.