The DIY electrolyte kit: four ingredients, one cart
I switched from $1.50-per-stick pre-mixes to four powders and a kitchen scale. Costs about $0.25 a bottle and works better for the kind of running I do.
The kit is four things. That’s the whole bill.
- Sodium chloride — Morton iodized salt
- Potassium chloride — Nutricost KCl powder
- Magnesium citrate — Natural Vitality Calm (unflavored)
- Dextrose — NOW Foods glucose powder
You’ll spend about $50–$70 to assemble the kit on Amazon, and it’ll make several hundred bottles’ worth of formula. Per-bottle cost lands around $0.20–$0.40 depending on how much carb you’re loading. Commercial equivalents (LMNT, Skratch, Precision) run $1.50–$3 per serving. That’s a 6–10× premium for the privilege of having someone else weigh your salt — fine if you’re an occasional 5K runner, less fine if you’re heading into 4-hour trail days.
Why each ingredient
Sodium chloride
Just table salt. Pure NaCl + iodine. By mass, table salt is 39.3% sodium — so 1 gram of salt delivers 393 mg of sodium. You want fine-grain (not sea salt or kosher) because the grain size has to be consistent for kitchen-scale doses to be accurate.
Don’t bother with “Himalayan pink” salt — it’s the same NaCl with trace minerals at concentrations too low to matter. You’d need to eat 10 grams of pink salt to get 0.1 mg of any minor mineral. That’s not how dose-response works.
Potassium chloride
KCl powder. 52.4% potassium by mass. Tastes mildly metallic on its own, but at the dose you’re putting in a bottle (200–400 mg of K = 0.4–0.8 g of powder), you won’t notice it once it’s mixed with salt and dextrose.
Get a third-party tested brand. Nutricost publishes their COAs. NOW Foods makes a version too. Avoid the “no-salt salt” products from the grocery store — they’re often only 60–70% KCl with the rest being anti-caking agents.
Magnesium citrate
This is the one you can argue about. Sweat magnesium losses are real but small — about 30 mg/L of sweat. At 1 L/hr that’s 30 mg/hr, and you only need to replace half because magnesium has a long body half-life. So a 500 ml bottle gets ~7 mg of Mg, which is functionally nothing.
I put it in anyway. Mg citrate is well-tolerated, may help with cramping (the evidence is mixed but plausible), and the cost is negligible.
Get unflavored Natural Vitality Calm — the flavored versions have stevia and citric acid that clash with your mix. The unflavored powder is roughly 80 mg of elemental Mg per gram of product, with citrate as the counter-ion.
Dextrose
Pure glucose powder. 4 kcal per gram, 1 gram of powder = 1 gram of carb for nutrition-label purposes.
Why dextrose specifically and not maltodextrin or sucrose? Two reasons:
- SGLT1 co-transport. Glucose and sodium are absorbed across the gut wall by the same transporter (SGLT1). They literally help each other across. Putting glucose with your sodium speeds up both.
- Single-sugar simplicity. For carb loads above 60 g/hr, you’d want to mix glucose with fructose (different transporter, additive capacity). But up to 60 g/hr, dextrose alone is fine and doesn’t need a second powder.
If you’re loading 90+ g/hr (ultra-distance), add fructose at a 1:0.8 glucose:fructose ratio. That’s a separate post.
What you don’t need
- Citric acid — only if you want sour. Doesn’t do anything physiologically. Skip it.
- Flavor powders — same. Most ruin the mix. If you must, add a squeeze of fresh lemon to the bottle.
- Sodium citrate / sodium bicarb — these are for endurance buffering, not hydration. Different topic. Don’t blend them in unless you know what you’re doing — they shift the pH and the taste hard.
- Stevia, sucralose, monk fruit — sweeteners are a personal call. I don’t bother. Dextrose at 4–8% concentration is already noticeably sweet.
- Encapsulated electrolyte pills — these are convenient but defeat the entire point of dosing by gram for your body.
The scale
Get one with 0.01 g resolution (sometimes called 10 mg resolution) and at least a 50 g capacity. American Weigh, Smart Weigh, anything in the $15–$25 range. The big chefs’ scales that read in 1 g increments are not precise enough — at our doses (0.5 g, 1.2 g, 2.8 g) a 1 g error is 20–80% off target.
This is the single most-skipped piece of the kit. Don’t skip it.
How fast it goes
My usage: one hot-weather long run a week (3 bottles) plus a couple of midweek runs (2 more bottles), about 30 useful weeks a year. Call it ~150 bottles. That’s:
- ~140 g of salt (less than half the 26 oz container)
- ~70 g of KCl (7% of a 1 kg bag)
- ~35 g of Mg powder (small dent in a 16 oz tub)
- ~2.7 kg of dextrose (most of a 2 lb bag — buy two)
You will run out of dextrose before anything else. The minerals last for years.
Ready to dose? Run the calculator and it’ll spit out grams for your bottle size and sweat profile.