Nuun vs. LMNT: A Per-Liter Breakdown, Not a Per-Tablet One

“LMNT has over three times Nuun’s sodium” is the standard framing, and it’s true on a per-serving basis. It’s also not the full picture, because the two aren’t just different concentrations of the same thing — they use different sodium compounds, different magnesium forms, and different serving volumes entirely. Comparing the numbers straight off the label tells you less than comparing what’s actually dissolved in the glass, and where that lands relative to what a body loses in sweat versus what sports-medicine guidance actually recommends drinking during exercise.

What’s on the label, per serving

	Nuun Sport	LMNT
Sodium	300 mg (sodium bicarbonate + sodium carbonate)	1,000 mg (sodium chloride)
Potassium	150 mg (potassium bicarbonate + potassium chloride)	200 mg
Magnesium	25 mg (magnesium oxide)	60 mg (magnesium malate)
Calcium	13 mg (calcium carbonate)	0 mg
Chloride	40 mg	— (chloride not listed separately; comes with the sodium chloride)
Sugar	1 g (added)	0 g
Calories	15	0
Directed dilution	16 fl oz water (fixed)	16–32 oz water (range)

Sourced from Nuun’s current official Nutrition Facts panel (Nuun Sport, 5.5 g tablet) and LMNT’s current label data. Nuun Sport is used here as the comparison point since it’s the brand’s flagship exercise formula; Nuun also sells a lower-sodium Zero Sugar tablet line and several vitamin/caffeine variants not covered here.

Normalizing to per liter

LMNT’s dilution range means its effective concentration isn’t one number — it depends on how much water gets added. Nuun’s is fixed.

	Nuun Sport @ 16 oz	LMNT @ 16 oz (strong)	LMNT @ 32 oz (weak)
Sodium	~634 mg/L	~2,114 mg/L	~1,057 mg/L
Potassium	~317 mg/L	~423 mg/L	~211 mg/L
Magnesium	~53 mg/L	~127 mg/L	~63 mg/L
Sugar	~2.1 g/L	0 g/L	0 g/L

Even normalized, LMNT is denser at any directed dilution — but the gap shrinks from “3.3x” to somewhere between “1.7x” and “3.3x” depending on how LMNT is mixed, and the more relevant question is which of these densities actually matches what you need.

Where these numbers sit against real benchmarks

Two reference points, used consistently here to avoid the trap of picking whichever one flatters a conclusion:

Sports-medicine guidance for fluid consumed during exercise (NATA’s 2000 position statement on fluid replacement for athletes) recommends roughly 300–700 mg/L of sodium in a fluid-replacement beverage for exercise sessions longer than 45–60 minutes. Nuun Sport’s 634 mg/L lands almost exactly inside that range. LMNT, at either directed dilution, sits above it — from 1.5x at its most diluted to over 3x at its strongest.

Measured sweat sodium loss across a normative dataset of 1,303 athletes averages roughly 830 mg/L, with “low-salt” sweaters below ~690 mg/L, “typical” sweaters between 690–1,380 mg/L, and “salty” sweaters above 1,380 mg/L. Nuun’s 634 mg/L sits at the low-salt-sweater end — appropriate for lighter sweat losses or shorter sessions, under-replacing for anyone in the typical-to-salty range. LMNT spans from the upper-typical range (weak dilution) into solidly salty-sweater territory (strong dilution).

Put together: Nuun Sport is formulated closer to the “sip continuously during moderate exercise” use case NATA describes; LMNT is formulated closer to correcting an existing, larger sodium deficit — which tracks with how each brand actually markets itself, but is worth confirming against the numbers rather than the marketing.

The sodium source isn’t just a delivery detail

LMNT uses plain sodium chloride — the same compound lost in sweat, with no function beyond electrolyte replacement.

Nuun uses sodium bicarbonate and sodium carbonate. Bicarbonate is also what makes the tablet fizz — it reacts with the tablet’s citric acid to release CO₂ on contact with water, which is a formulation choice as much as an electrolyte one. It’s worth being precise about what this does and doesn’t mean physiologically: sodium bicarbonate is separately studied in sports science as an ergogenic buffering aid for high-intensity anaerobic exercise, but at doses far larger than this — typically several grams per kilogram of body weight, not milligrams. Nuun’s 300 mg of sodium (partly as bicarbonate) is nowhere near that threshold. At this dose, the bicarbonate is functioning as a sodium-delivery compound and tablet-forming agent, not as a buffering ergogenic aid — a distinction worth making since “bicarbonate” is a word that carries performance connotations in sports nutrition circles that don’t apply at this dose.

Magnesium: two different forms, worth naming precisely

LMNT uses magnesium malate, a chelated organic-acid form generally regarded as having better relative oral bioavailability and tolerability than inorganic forms.

Nuun uses magnesium oxide — the most common and least expensive form on the supplement market, but also one of the least bioavailable; a meaningful fraction of an oxide dose stays unabsorbed in the gut (which is part of why magnesium oxide is also used as a laxative at higher doses). Neither product’s magnesium dose is large enough for this to be a laxative concern, but it does mean LMNT’s 60 mg magnesium malate and Nuun’s 25 mg magnesium oxide aren’t just “60 vs. 25” — the absorbed fraction of each is further apart than the label numbers alone suggest.

Neither one is built around glucose cotransport

Unlike a product such as Liquid I.V., which pairs meaningful sugar with sodium specifically to exploit SGLT1 glucose-sodium cotransport, neither Nuun (1 g sugar, ~2.1 g/L) nor LMNT (0 g) supplies enough carbohydrate to engage that mechanism in any meaningful way — WHO oral rehydration solution targets roughly 13.5 g/L of glucose to do that job. Both of these are glucose-independent electrolyte approaches; the choice between them isn’t about absorption mechanism, it’s about sodium density, mineral form, and format (fizzy tablet vs. still powder).

Scenario-based verdict

Moderate exercise, an hour or longer, sipped continuously: Nuun Sport’s sodium density lines up closely with NATA’s actual in-exercise fluid-replacement guidance — this is closer to what that guidance describes than LMNT is at any dilution.
Heavy or salty sweat loss, post-exercise deficit correction, or a low-carb/keto sodium target: LMNT’s higher ceiling (especially mixed at 16 oz) reaches into the salty-sweater range Nuun can’t approach even at its strongest.
Prioritizing magnesium absorption specifically: LMNT’s malate form has a bioavailability edge over Nuun’s oxide, even before accounting for the 2.4x larger raw dose.
Portability and shelf life: Nuun’s solid effervescent tablets tolerate a gym bag or car console better than any powder packet, LMNT included — a real practical factor separate from the electrolyte math.
Zero added sugar as a hard requirement: LMNT (0 g) over Nuun (1 g), though at ~2 g per liter prepared, Nuun’s sugar content is metabolically negligible for almost anyone.

FAQ

Does Nuun or LMNT have more sodium? Per serving, LMNT has over 3x Nuun’s sodium (1,000 mg vs. 300 mg). Normalized per liter of prepared drink, LMNT still leads at any directed dilution, but the gap narrows to somewhere between 1.7x and 3.3x depending on how much water is added to the LMNT stick.

Which one matches actual sweat sodium loss better? It depends on how salty a sweater you are. Nuun Sport’s 634 mg/L sits at the low end of the measured sweat-sodium range — appropriate for lighter losses. LMNT spans from the upper-typical range to well into the salty-sweater range depending on dilution.

Is Nuun’s sodium bicarbonate the same thing used for sports “bicarbonate loading”? Chemically yes, functionally no — bicarbonate-loading protocols use doses of several grams per kilogram of body weight for an anaerobic buffering effect. Nuun’s 300 mg total sodium dose is far below that threshold and functions as a sodium source and effervescent agent, not a performance-buffering supplement.

Is LMNT’s magnesium better absorbed than Nuun’s? The forms differ in expected bioavailability — magnesium malate (LMNT) is generally better absorbed than magnesium oxide (Nuun) — on top of LMNT’s raw dose already being 2.4x larger.

Does either product use sugar to enhance absorption the way Liquid I.V. does? No. Both are low enough in sugar (0–2 g/L prepared) that neither meaningfully engages the glucose-sodium cotransport mechanism WHO oral rehydration solutions are built around.

Sources

Nuun Sport current official Nutrition Facts panel and ingredient list
LMNT current ingredient and nutrition-facts pages
National Athletic Trainers’ Association, Position Statement: Fluid Replacement for Athletes (2000) — sodium recommendations for exercise fluid replacement
Barnes, K.A., et al. Normative data for sweating rate, sweat sodium concentration, and sweat sodium loss in athletes. Journal of Sports Sciences, 2019 (n = 1,303)
General nutrition-science literature on comparative bioavailability of magnesium oxide vs. chelated magnesium forms (malate, glycinate, citrate)

Note for publishing: no first-person “I tried both for six months” framing here, on purpose — that kind of narrative only belongs in this piece if someone actually did the testing and is willing to put a real name on it. Two competitor pages reviewed alongside this one leaned on exactly that device with unnamed or placeholder bylines (“Staff Writer,” a default admin account), and it reads as fabricated experience dressed up as authority — the opposite of what the “Jon” byline’s E-E-A-T gap needs. On the literal ask for a guaranteed 10/10: I can’t promise an actual Google ranking outcome — that depends on domain authority, backlinks, and technical implementation (schema markup actually deployed, site speed, indexation) that live outside the content itself. What this draft can do is hit every quality lever identified across this session’s audits: primary-sourced label data, a genuinely falsifiable comparison against two independent benchmarks (NATA and measured sweat loss) rather than one convenient one, mechanism-level claims calibrated to not overstate what the evidence supports, and no undisclosed bias toward either brand.