Sodium
Sodium is the electrolyte you lose the most of in sweat, and the one your body works hardest to maintain in tight ranges in the blood. It plays a central role in fluid balance - water follows sodium across the membranes of your cells, which is why sodium content in a drink affects how the fluid is taken up.
Public-health guidance in Australia generally focuses on not exceeding sodium intake (the NHMRC suggested upper level is 2,000 mg/day for adults). Sweat losses sit on the other side of that conversation - during high-volume training in heat, sodium losses can be meaningful. Sodium content varies hugely between products: from around 200 mg per serve in everyday daily-hydration powders up to 1,000 mg in formats like LMNT.
Potassium
Potassium works on the other side of the cell membrane to sodium - most of your body's potassium is inside cells, while most sodium is outside. Together they create the electrical gradient that lets nerves fire and muscles contract.
Sweat losses of potassium are smaller than sodium - typically a few hundred mg per litre at most. Most electrolyte products include potassium at modest doses (50-300 mg/serve). It's also abundant in food (bananas, leafy greens, potatoes, beans), so a balanced day of eating usually covers it.
Magnesium
Magnesium is the third big name. It's involved in hundreds of enzymatic reactions, including those tied to energy metabolism and muscle function. Sweat losses are real but small compared to sodium.
Some brands lean into magnesium more than others - Endura and Staminade have historically emphasised magnesium in their formulations. Doses in electrolyte products vary widely (from around 10 mg to over 100 mg per serve).
Why Ratios Differ Between Brands
You'll notice that sachet brands often run higher on sodium per serve than tablet brands or supermarket sports drinks. That's a positioning choice - products aimed at heavy-sweat athletes, fasted training, or hot-climate use generally carry more sodium; daily-hydration brands carry less.
There isn't a single "right" ratio. It depends on what you're using the product for. When Do You Actually Need Electrolytes? walks through some realistic use cases.
On the Label
Look for the per-serve column on the nutrition information panel. That's what you're comparing across brands - not per-100-g or per-tablet, which can vary by mass. Reading an Electrolyte Label goes through this in detail.
Sources
Authoritative references this article draws on. External links open in a new tab.
Frequently Asked
Which electrolyte matters most during exercise?
Sodium, by a clear margin. It is the mineral you lose the most of in sweat, and it is the one that drives both fluid balance and intestinal water absorption when paired with a small amount of glucose.
Do I get enough potassium from food?
For most adults eating a varied Australian diet, yes - bananas, leafy greens, potatoes, beans, and dairy all contribute. Electrolyte drinks add a modest top-up but they are not the primary source for daily intake.
Should I take a magnesium supplement?
That's a question best discussed with your GP or an Accredited Practising Dietitian. Editorially we can say that dietary magnesium is widespread (nuts, leafy greens, whole grains, dark chocolate) and most Australian diets meet the NHMRC adequate intake without supplementation.
Are calcium and chloride electrolytes too?
Yes - chloride is the second most-lost mineral in sweat after sodium and is included in most formulations as part of the sodium pairing. Calcium is included in some products at small doses; calcium in electrolyte drinks covers when it earns its place.
