DIY Sports Drink Calculator

A commercial sports drink is water, sugar, salt and marketing in a patented ratio — and the ratio is published science. Enter your bottle size, the carbohydrate strength you want and a sodium target, and this calculator weighs out your homemade version: grams of sugar, grams of table salt, and the calories in the bottle.

The Three Ingredients, Priced Honestly

Sports-drink science reduces to three levers, each with a physiological job. Carbohydrate (the calculator's percentage, grams per 100 mL by the sports-science convention) fuels the work and, crucially, drags water across the gut wall via the glucose–sodium co-transport pump — the discovery, from cholera rehydration research, that built this entire product category. Sodium replaces sweat's main electrolyte, holds the fluid in the body rather than letting it straight through, and keeps thirst switched on; commercial drinks run 460–690 mg per litre and heavy or salty sweaters may need the calculator's upper ranges on long days. Water is the point of the exercise. Everything else in the bottled article — colour, flavour, the potassium garnish — is decoration at these doses. The calculator's job is to get the two weighed ingredients right for your bottle; the kitchen supplies the rest for pennies against the branded article's price per litre, which is the open secret of this page's existence.

Worked Example: The 750 mL Bottle at Classic Strength

The defaults mix the archetype: a 750 mL bidon at 6% carbohydrate with a 600 mg/L sodium target. Sugar: 0.75 × 6 × 10 = 45 g (about 11 level teaspoons, or 3 heaped tablespoons — the calculator wants you to weigh it once and learn your spoon's dialect). Sodium: 0.75 × 600 = 450 mg, which as table salt (39.3% sodium by mass: 450 ÷ 0.393) is 1.15 g of salt — about a fifth of a level teaspoon, a generous pinch with table manners. Energy in the bottle: 45 × 4 = 180 kcal, delivered at roughly the rate endurance guidelines prescribe for the second hour onward when drunk steadily. That recipe — sugar, a pinch-scale of salt, citrus to taste — is functionally the drink on the supermarket shelf, at perhaps a twentieth of its cost per litre, which is why the DIY page of this hub is a favourite of every high-mileage amateur alive.

Strength, Duration and the Gut's Ceiling

The selector's three strengths map to the exercise science consensus on fuelling: sessions under an hour need water alone (the 4% light mix is for palates and short-second-hours); the classic 6% serves the 1–2.5 hour band where 30–60 g of carbohydrate per hour is the target; the strong 8% approaches the intestinal comfort ceiling, beyond which drinks empty slowly and slosh — at and beyond which the modern practice is to split the difference with glucose-plus-fructose blends (the two sugars use different gut transporters, raising the absorption ceiling toward 90 g per hour for events long enough to need it, which the calculator's note gestures at with its maltodextrin suggestion). Potassium, magnesium and the rest of the electrolyte periodic table are lost in sweat in quantities the diet replaces at the next meal; sodium is the one whose acute absence ends days early, and it is the one this page makes you measure. Mix, taste for "pleasantly seasoned, faintly sweet", and train the gut with the race-day bottle, never the reverse order.

The Oral Rehydration Lineage

The drink in your bottle descends from one of medicine's greatest hits: oral rehydration therapy, the glucose-electrolyte solution whose discovery The Lancet called potentially the most important medical advance of the twentieth century, which cut cholera's mortality from a third to under one percent wherever it reached in time. Sports science borrowed the co-transport mechanism, diluted the salt to training tolerances, added flavour, and built an industry — the honest history this page stands in, and the reason its recipe's ratios deserve respect out of proportion to their simplicity. When your kitchen scale weighs out 1.15 grams of salt for a bidon, it is measuring the recreational dose of a therapy that has saved tens of millions of lives: a pedigree no energy gel can match.

Caffeine, and Other Legal Additions

The home mixer's advanced shelf holds one ingredient with genuine evidence behind it: caffeine, at roughly 3–6 mg per kilogram of body weight taken in the hour before and during long events, improves endurance performance by a few percent through central-nervous-system channels — a strong coffee before the start is the classic delivery, and caffeinated mixes exist for those who tolerate them mid-race. Everything beyond caffeine descends quickly into garnish economics (the calculator's three-ingredient discipline is the audit): if an additive cannot state its mechanism and its dose-response as crisply as sugar, sodium and water state theirs, it is flavouring wearing a lab coat, priced accordingly by the experienced.

Winter Training and the Warm Version

The recipe has a cold-weather afterlife its summer inventors underplay: in winter the failure mode flips — athletes under-drink because thirst dulls in the cold while sweat continues under layers — and a warm, palatable bottle (the same ratios, mixed with warm water and taken as a mild sweet tea of effort) measurably improves voluntary intake on long cold sessions. The sodium's job is unchanged; the carbohydrates double as genuine warmth-adjacent fuel when the body's furnace is splitting its output between muscles and temperature. It is the same calculator, the same grams — only the serving temperature and the season's psychology differ, which is this page's closing reminder that hydration formulas are constant and hydration behaviour is the variable that actually decides outcomes.

Related Tools

More from the Sports Calculators hub: the Calories Burned by Heart Rate Calculator to size the session this bottle fuels, and the Anaerobic Threshold Calculator — the intensity above which no drink can keep up with the burn.

Frequently Asked Questions

Can I just use this instead of commercial sports drinks?

For training and most racing, yes — the active ingredients and their ratios are what this calculator replicates, and the commercial advantages are convenience, consistent flavouring and, in the premium lines, the glucose-fructose blends and caffeine variants you can also replicate at home (maltodextrin from a homebrew supplier, as the note suggests). What the homemade version lacks is the lab: weigh carefully, because the recipe's entire virtue is its ratios, and a heavy-handed salt pour produces an undrinkable — and at the extreme, unhelpful — bottle. Kitchen scales cost less than a case of the branded article.

How much should I drink per hour?

To thirst, within the guardrails the literature converged on: most athletes in most conditions land at 400–800 mL per hour, smaller and cooler toward the low end; drinking beyond sweat losses (gaining weight during an event) courts hyponatremia, the genuinely dangerous failure mode of endurance hydration, whose prevention is one reason this drink contains sodium and this paragraph contains restraint. Weighing yourself before and after long training sessions calibrates your own sweat rate once, and the calibration outlives any chart — the bottle this calculator mixes is then simply the vehicle for the volume your body actually asked for.

Is the salt really necessary for a one-hour run?

Honestly, no — for sessions under about an hour, water alone serves, and the calculator's 4% light option exists for taste as much as physiology. Sodium's hour comes with duration, heat and heavy or salty sweating (the white tide-marks on kit are sodium's signature and its owner's hint to use this page's higher targets). The recipe scales honestly in both directions because its author is a ratio, not a brand: what matters is that when the long day arrives, the drink you mix matches the drink the science describes.

What can I use instead of table sugar?

Any carbohydrate the gut tolerates: honey and maple syrup are mostly glucose and fructose with flavour included (weigh them as roughly 80% sugar by mass, so divide the calculator's grams by 0.8); fruit juice concentrate works diluted; maltodextrin — nearly tasteless — is the professional's choice at high strengths, usually blended half and half with table sugar or fructose to engage both absorption routes. Brown versus white sugar is a flavour decision, not a physiological one. What does not work: artificial sweeteners, which deliver the taste with none of the fuel the formula is counting.

Why does the drink need sugar for hydration at all?

Because the gut's fastest water tap is co-transport: the SGLT1 transporter pulls sodium and glucose through the intestinal wall together and water follows osmotically — the mechanism that makes oral rehydration solution save lives and that sports drinks inherited. Plain water absorbs fine too, more slowly, and dilutes blood sodium as it goes (one root of the hyponatremia warning); the sugar-salt pairing is not a flavour conspiracy but plumbing. It is also why the recipe's ratios matter in both directions — too strong a mix slows gastric emptying, too weak forfeits the pump — and why this calculator exists to land the bottle in the narrow, effective band between.

Can I make a big batch for the week?

Mix the dry ingredients in batch (sugar and salt in the calculator's ratio, scaled to the week's bottles, stored in a jar with the per-bottle scoop count written on it) and add water and citrus fresh — the drink itself, mixed, keeps a few days refrigerated but tastes its age. Race-week discipline suggests mixing the actual race bottles the night before and no earlier: freshness aside, the ritual of weighing the race-day recipe is the last quality-control step between the science and the start line, and it has caught more forgotten-salt disasters than any checklist.