The Best Electrolyte Powders, Compared by the Numbers That Matter

One serving of Ultima Replenisher has 55 mg of sodium. One stick of LMNT has 1,000 mg. Both are sold as electrolyte powders, both go into a glass of water, and there is an eighteen-fold difference between them.

That gap is the single most useful thing to understand about this category, and it is the reason a ranked "best electrolyte powder" list is mostly noise. There is no winner. There is a right amount of sodium for your sweat rate and your activity, and then a price you are willing to pay per glass.

Everything below comes from the manufacturer's own nutrition or supplement facts panel, read directly off the product page or the packaging image on the brand's site, with the exact SKU pinned. We did not test anything in a lab, and we did not copy figures from other comparison articles — a lot of the contradictions floating around this category come from exactly that.

Here is what this guide covers:

• What the four numbers on the label actually do. Sodium, potassium, magnesium, added sugar, and which of them genuinely differentiates products.
• A verified per-serving comparison. Eight products, sodium sorted high to low, with the water volume each brand tells you to use.
• The serving-size trap. Why one guide lists DripDrop at 330 mg and another lists it at 660 mg, and how to spot the same problem elsewhere.
• How to match a powder to your use case. Heavy sweating, recovery from illness, keto and fasting, and everyday sipping.
• Electrolyte brands you can shop with Flex. Four in the marketplace right now.

What the numbers on the label actually mean

Electrolytes are minerals that carry an electrical charge in solution. Your body uses them to move fluid between cells, fire nerve signals, and contract muscles. You lose them mostly through sweat, and secondarily through urine, vomiting, and diarrhea.

Four numbers on the panel determine whether a given powder suits you.

Sodium — the one that varies

Sodium is the primary electrolyte lost in sweat, and it is what drives your body to hold onto the water you drink rather than pass it straight through. It is also the number that swings hardest between products, which is why it is worth checking before anything else on the label.

How much you personally lose is not a fixed quantity. Gatorade Sports Science Institute researcher Lindsay B. Baker writes that sweat sodium "typically ranges from ~10 to ~90 mmol/L (when measured via local methods)" — roughly 230 to 2,070 mg per liter of sweat once converted. Two people doing the same workout side by side can be at opposite ends of that. It is the honest reason a powder feels transformative to one person and pointless to another.

For scale: the FDA Daily Value used to calculate the % figures printed on these labels is 2,300 mg of sodium. A single LMNT stick is about 43% of that.

Potassium and magnesium — usually not the deciding factor

Potassium works alongside sodium to regulate fluid inside your cells. You lose much less of it in sweat than sodium, and most people get a reasonable amount from food.

Magnesium is involved in muscle function and energy metabolism, and it is the mineral most often flagged as under-consumed. Amounts here run from nothing at all to 100 mg, against daily targets in the hundreds. Treat it as a bonus, not a source.

Both matter. Neither is usually the reason to pick one product over another — sodium is.

Added sugar — the most misread number on the panel

Glucose is not a filler that snuck into your hydration drink. It is the mechanism. Oral rehydration solutions work because sugar and sodium are absorbed together across the gut wall, dragging water with them; a 2023 paper in Molecules puts it plainly: "The use of ORS stimulates fluid uptake through SGLT1." The World Health Organization describes oral rehydration salts as, simply, "a mixture of clean water, salt and sugar."

So a powder with 11 g of sugar is not a worse version of a sugar-free one. It is a different tool. If you are rehydrating during hard exercise or recovering from a stomach bug, the sugar is doing work. If you are sipping at a desk, on keto, or fasting, it is about 50 calories you did not need.

Electrolyte powder comparison: verified per-serving figures

Every figure below is from the manufacturer's own panel for the exact SKU named. Sorted by sodium, high to low. Cost per serving is manufacturer-direct list price divided by servings, checked October 22, 2026, excluding subscription discounts.

Two things jump out. Ultima is not a low-sodium version of the others — at 55 mg it is barely in the same category, and it compensates with the highest magnesium here. And Skratch has almost no potassium (50 mg) despite being the most performance-oriented product on the list, because it is formulated to mirror the ratio actually lost in sweat, which is overwhelmingly sodium.

The serving-size trap

If you have read other comparisons, you may have seen DripDrop listed at 660 mg of sodium. Its label says 330 mg. Both are true: DripDrop tells you to mix one 10 g stick into 8 oz of water, so two sticks — the amount most people use to fill a 16 oz bottle — is 660 mg.

Pedialyte does the same thing inside its own product line. The 8.5 g Classic Powder Pack goes into 8 fl oz and has 260 mg of sodium and 180 mg of potassium. The 17 g Classic Powder Pack goes into 16 fl oz and has 490 mg and 370 mg. Same brand, same product name, roughly the same concentration, wildly different per-serving numbers.

Liquid I.V. splits a different way: the original and the Sugar-Free version have identical sodium and potassium, and differ only in sugar and calories.

So before you compare two products, check three things: the exact SKU, the serving size in grams, and the water volume the brand tells you to use. A per-serving number with no volume attached — which is the situation with LMNT's product page — tells you what is in the packet, not how concentrated your drink will be.

How to match a powder to how you'll actually use it

If you sweat heavily or train in heat

Prioritize sodium and treat everything else as secondary. LMNT at 1,000 mg is the most aggressive mainstream option, and it is unapologetic about it — the brand's own guidance for sessions over an hour in the heat is "16–20 oz of water with ½ – 1 LMNT stick pack per hour." For efforts past about 90 minutes, carbohydrate starts earning its place too, which points toward Skratch, whose 16 g of added sugar (in the Mango flavor — sugar varies by flavor) is fuel rather than sweetener.

If you're rehydrating after illness

You want the oral rehydration profile: real sodium plus glucose to drive absorption. Pedialyte is built precisely for this and is the most conservative choice. DripDrop is formulated on the same principle. A zero-sugar powder is the wrong tool here — it removes the part that makes rehydration fast.

If you're on keto or fasting

Cutting processed carbohydrate removes a large share of most people's dietary sodium, which is why the first weeks of a low-carb diet often come with headaches and fatigue. A high-sodium, zero-sugar powder addresses that directly, and LMNT is the obvious fit. Liquid I.V. Sugar-Free is the gentler version at 500 mg.

If you want everyday hydration

You need much less than the marketing implies. Nuun at $0.75 a serving is the cheapest option here and modest across the board. Ultima is the choice if what you actually want is magnesium with a bit of flavor, since its sodium is essentially token. Neither will make your water taste like seawater, which is a real consideration if you are drinking it daily.

How much sodium do you actually need?

The honest answer is that it depends on how much you sweat and for how long, and most people estimate from marketing rather than from sweat loss.

A rough check: weigh yourself before and after an hour of your typical exercise, without drinking. Each pound lost is roughly 16 oz of sweat. Someone losing two pounds an hour outdoors in August is in genuinely different territory from someone losing half a pound in an air-conditioned gym, and only the first person has a use for a 1,000 mg product.

Signs you may be under-replacing sodium include cramping late in long sessions, visible salt on skin or clothing afterward, headaches after heavy sweating, and feeling worse rather than better after drinking a lot of plain water.

Sodium is not universally benign, and this is the part the category tends to skip. If you have high blood pressure, kidney disease, or heart failure, or you have been told to limit sodium, talk to your clinician before adding a high-sodium powder to your routine. And if a clinician has given you a specific sodium target, follow their number, not a product label. Nothing here is medical advice.

4 electrolyte brands you can shop with Flex

These four hydration brands are sold in the Flex nutrition category. They aren't in the comparison table above, so check each product page for the current supplement facts panel, since formulations change and most brands run more than one line.

Whether HSA or FSA funds can be used for electrolyte products depends on IRS rules and your plan; our guide to whether electrolytes are HSA/FSA eligible explains how it works.