How many carbs per hour should I eat on the bike?

For rides over 90 minutes, sports scientists recommend 30-60g of carbohydrate per hour at moderate intensity and up to 90g per hour for hard, long efforts using a glucose-plus-fructose mix. This calculator scales within that range by your chosen intensity.

How much should I drink per hour?

A common starting point is 500-750ml of fluid per hour, rising in heat or at high intensity. Your true need depends on sweat rate, so weigh yourself before and after a ride to refine the estimate over time.

Why does the tool estimate sodium?

Sweat carries sodium, and on long or hot rides losses can cause cramps and fatigue. A typical sweat sodium concentration is around 800-1000mg per litre, so the tool multiplies estimated fluid loss by that to suggest electrolyte intake.

Can I exceed 60g of carbs per hour safely?

Yes, but only with a mix of glucose and fructose, because each uses a different gut transporter. Train your gut gradually toward 80-90g per hour before relying on it in a race, and avoid this level on easy rides where it is unnecessary.

Does this replace a sports dietitian?

No. These figures follow published endurance guidelines and are a solid starting point, but individual tolerance, heat acclimation, and gut training vary a lot. Use the numbers to build a plan and adjust based on real-ride experience.

Cycling Nutrition & Carb Calculator

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Fuel the ride before you bonk

Running out of carbohydrate — bonking — is the classic way a long ride falls apart, and under-drinking quietly drains performance long before thirst hits. This calculator turns ride duration, intensity, and bodyweight into concrete targets: carbohydrate per hour, total carbs to carry, fluid per hour, and estimated sodium to replace.

How it works

Carbohydrate need is driven mostly by intensity and duration, not weight, so the tool picks a grams-per-hour rate by intensity:

easy / endurance     ->  40 g/h
moderate / tempo     ->  60 g/h
hard / race          ->  85 g/h
total_carbs = rate * hours

Fluid and sodium scale with sweat, which rises with both intensity and body mass:

fluid_ml_per_hour = base_rate(intensity) * (weight_kg / 70)
sodium_mg_per_hour = fluid_litres_per_hour * 900

The base sweat rate ranges from about 500 ml/h easy to 850 ml/h at race pace, normalised to a 70 kg reference rider, and 900 mg/L reflects a typical sweat sodium concentration.

Example and tips

A 75 kg rider planning a 4-hour tempo ride needs about 60 g/h × 4 = 240g of carbs, roughly 650 × (75/70) ≈ 700 ml of fluid per hour, and around 630 mg of sodium per hour. Carry that as a mix of bars, gels, and drink mix, start fuelling within the first 30 minutes rather than waiting until you feel empty, and practise your race-day intake on training rides first.