Why I built salz.run

Hi, I’m Sean. I run on trails when I can and sit on the couch when I can’t. I’m not fast. I’ve never been sponsored. I’m signed up for my first 100K next year and I’m currently doing about 42 miles a week, which I’m slowly bumping up because the calendar isn’t on my side.

I’m also a heavy sweater. The kind where my hat develops a salt rim by mile 6 and my eyes start stinging an hour in. For years I bought the nice electrolyte powders — LMNT, Skratch, Precision — because the marketing said they were for people like me and the orange flavors were good.

What I didn’t do for years was the math.

The math

LMNT is about $1.50 a stick. At my volume, a heavy summer week means three sticks on the Saturday long run and two more across the rest of the week. Call it five sticks, $7.50 a week, $30 a month. Skratch and Precision land in roughly the same place. Add Precision PH 1500 ($3+ a bottle for the high-dose ones) and the number creeps north of $50–$80 in a hot month.

That’s not nothing. That’s a pair of trail shoes every quarter.

Meanwhile a 26 oz canister of Morton salt costs $2 and lasts approximately forever. A 1 kg bag of potassium chloride is $14 and lasts longer. Magnesium powder, dextrose — all in, the four-powder kit runs about $55 once and mixes hundreds of bottles after that.

The math is rude. About 10× cheaper, gram for gram of actual electrolyte.

The catch

The catch is that pre-mixed sachets are tuned for the average person on the couch, not for me on a 4-hour mountain day in July. The sodium dose in an LMNT stick (1,000 mg Na) is great if you’re a moderate sweater going for an hour. For my actual sweat rate and a 4–6 hour run, I need closer to 1,800–2,400 mg of sodium an hour, which is two sticks plus an extra pinch.

By the time I’ve torn open three sachets, dumped them in three bottles, and tried to remember which one I drank already, I’ve spent $4.50 and I’m still under-dosed.

If I’m going to mix custom doses anyway, why not just weigh the ingredients myself.

What salz.run does

Four ingredients. Kitchen scale. Bottle.

1. Sodium chloride — table salt
2. Potassium chloride — KCl powder
3. Magnesium citrate — Natural Vitality Calm, unflavored
4. Dextrose — pure glucose powder for the carbs

The calculator does the dosing for me — for my body weight, my sweat rate, the conditions I’m running in, the bottle I’m carrying. Out comes a recipe in grams. I weigh, I pour, I shake.

Per-bottle cost lands around $0.25–$0.40. The salt rim on my hat returns. The eye stinging mostly stops.

What this site is for

Honestly? Mostly for me. The calculator is a thing I needed, and putting it on the internet is cheaper than maintaining it in a Google Sheet I’d lose track of by July.

If it’s useful to you too, I’m glad. The Amazon links earn me a few cents per click — that’s the entire monetization. I’m not selling courses, I’m not sliding into your DMs, and I’m not running a Substack to upsell into anything. The blog is just where I write down what I’m trying on my own legs.

I’d love to hear from you if you spot an error in the math or have a protocol I should try. My email and LinkedIn are on the about page. Real person, real legs, real salt rim.

See you out there.