How this instrument works
Commercial sports drinks are formulated around two main ingredients beyond water: carbohydrate, for fuel during exercise, and sodium, to help retain fluid and reduce the risk of hyponatremia during longer sessions. The American College of Sports Medicine's position stand on exercise and fluid replacement recommends roughly 4-8% carbohydrate concentration and about 500-700 mg of sodium per liter for fluids consumed during exercise lasting over an hour — the exact range this calculator's default carbohydrate (6%) and sodium (500 mg/L) inputs sit within.
This calculator converts those percentage-based targets into two simple grocery-list quantities: grams of ordinary table sugar (sucrose) for the carbohydrate portion, and grams of table salt (sodium chloride) for the sodium portion. Since sodium is only about 39.3% of table salt's mass by weight (the rest being chloride), the calculator divides your target sodium mass by that 0.393 conversion factor to get the actual grams of salt needed — a chemistry constant, not a nutrition guideline.
This produces a straightforward electrolyte-and-carbohydrate mix, not a full nutritional replica of any specific commercial product — it doesn't include added flavoring, potassium, or other minor electrolytes some sports drinks contain. For most exercise under an hour, plain water is generally sufficient per ACSM guidance; this kind of mix is intended for longer or hotter-condition sessions where carbohydrate and sodium replacement genuinely help.
- Enter Batch volume in liters — how much drink you're making.
- Enter Target carbohydrate concentration as a percentage — ACSM's guidance range is roughly 4-8%.
- Enter Target sodium concentration in mg per liter — ACSM's range is roughly 300-700 mg/L for this calculator's slider.
- Read Table sugar to add in grams — dissolve fully into your total water volume.
- Read Table salt to add in grams — stir in alongside the sugar until fully dissolved.
Worked example — a 1-liter batch at ACSM's typical mid-range targets
Enter 1 liter for batch volume, 6% for carbohydrate concentration, and 500 mg/L for sodium — both squarely inside ACSM's published ranges. Sugar comes out to 1 x 1000 x (6/100) = 60 g, roughly 5 tablespoons. Salt comes out to (1 x 500/1000) / 0.393 = 0.5 / 0.393 = 1.27 g, a little under a quarter teaspoon.
Dissolving 60 g of table sugar and 1.27 g of table salt into 1 liter of water produces a drink in the same carbohydrate and sodium range as most commercial sports drinks, at a fraction of the cost. Scaling up to a 2-liter batch at the higher end of ACSM's range (8% carb, 700 mg/L sodium) needs 160 g sugar and 3.56 g salt — proportionally more of both, since doubling the volume doubles the sugar requirement and both volume and concentration scale the salt requirement together.
Questions
Why table sugar and table salt specifically?
Table sugar (sucrose) is a readily available, inexpensive carbohydrate source that the body absorbs and uses for fuel during exercise, and it's the ingredient most homemade sports-drink recipes are built around. Table salt (sodium chloride) is likewise the simplest, cheapest way to add sodium at home. Commercial sports drinks sometimes use other carbohydrate sources (like glucose or maltodextrin blends) and other sodium compounds, but sucrose and sodium chloride achieve the same functional goal for a DIY version.
Do I need a sports drink at all, or is water enough?
For exercise sessions under about an hour, ACSM's own guidance generally considers plain water adequate for most people. Carbohydrate-and-sodium drinks become more useful for exercise lasting longer than an hour, in hot conditions with heavy sweating, or for high-intensity efforts where maintaining blood glucose and replacing sodium losses genuinely helps performance and reduces hyponatremia risk. Match the tool (water vs. a formulated drink) to the actual demands of your session.
Why does the calculator divide sodium by 0.393 to get salt grams?
Table salt (sodium chloride, NaCl) is a compound of two elements, and sodium only accounts for about 39.3% of its total mass — the remaining roughly 60.7% is chloride. So if you want a specific mass of sodium, you need more than that same mass in salt; dividing the target sodium mass by 0.393 gives you the actual salt mass required to deliver it. It's a fixed chemistry constant, not something that varies by recipe or brand of salt.
Can I add flavoring or juice to this base recipe?
Yes — this calculator handles only the carbohydrate and sodium math; flavoring (citrus juice, a small amount of squash or cordial, or a pinch of a flavored electrolyte mix) is commonly added afterward purely for palatability and doesn't change the sugar or salt amounts calculated here. Just be aware that adding juice introduces its own sugar content, which would push your total carbohydrate concentration above the calculated target unless you reduce the added table sugar to compensate.
Is 6% carbohydrate and 500 mg/L sodium the 'right' recipe for everyone?
Those are simply the calculator's defaults, chosen because they sit in the middle of ACSM's published ranges (roughly 4-8% carbohydrate, 500-700 mg/L sodium) for fluids consumed during exercise longer than an hour. Individual sweat rate, sweat sodium concentration, exercise intensity, and heat conditions all vary, so endurance athletes with heavy or salty sweat losses often target the higher end of the sodium range, while shorter or cooler sessions can use less. Adjust both sliders to match your own conditions rather than treating the defaults as fixed.