Hydration science without the sachet tax — branded electrolytes vs DIY sodium and potassium

Sweat is not pure water. You lose sodium (Na⁺), chloride (Cl⁻), and smaller amounts of potassium (K⁺) and magnesium (Mg²⁺). Sports and ‘keto’ brands package that as clinical stick packs. The chemistry is table salt, potassium chloride and a magnesium salt dissolved in water — citric acid and stevia for taste.

DupeStack’s job is the cost-per-serving maths. When a box of 30 sachets costs ~£42, you are paying well over a pound a stick for grams of commodity minerals. The LMNT teardown puts bulk DIY near £0.06-class ingredient cost per serving before flavour.

A representative high-sodium stick (LMNT-style) lists on the order of 1,000 mg sodium, 200 mg potassium and 60 mg magnesium. Convert to weighing mass carefully: sodium comes from NaCl (table or rock salt) — roughly 2.5 g fine salt supplies about 1,000 mg Na. Potassium from KCl is roughly 380 mg KCl for 200 mg K. Magnesium at 60 mg elemental needs a salt-specific calculation (malate and glycinate are not the same compound weight).

Batch-mix dry powders in a jar, scoop with a level teaspoon once you have calibrated it, and dissolve in ~750 ml water. That is the same ion story as the sachet without the stick-pack tax. Use a 0.1 g scale the first time — kitchen spoons lie.

Endurance athletes, outdoor workers in heat, and some very low-carbohydrate diets can run low on sodium relative to water intake. A salty drink can be rational in those contexts. It is not a default ‘optimisation’ for sedentary office days, and it is a poor idea if you have been told to restrict salt.

Potassium and magnesium doses in these sachets are modest compared with food. They are not a licence to megadose KCl (dangerous in excess) or to treat cramp as a magnesium deficiency without labs. Food-supplement comparison only.

Beam Dream and Nutrition Geeks glycinate target evening oral magnesium rituals — different job, different salt maths. BetterYou ‘oil’ is topical chloride brine. None of those replace a weighed NaCl + KCl drink when the goal is sweat replacement.

Pick one teardown that matches the label in your hand. Run the calculator or the serving maths once. Then buy bulk salts sized for weeks of use, not a month of foil sticks.

Food-grade salts only — not fertiliser-grade muriate of potash from the garden shed, not laboratory reagents of unknown purity. Keep KCl away from children; accidental overdose is a medical emergency.

People with kidney disease, on ACE inhibitors/ARBs, potassium-sparing diuretics, or heart-failure fluid restriction need clinician guidance before DIY electrolyte stacks. DupeStack compares shop maths, not prescriptions.