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Tool Comparison

Sodium Calculator Comparison

An honest, brand-neutral comparison of the five most-cited endurance sodium and hydration tools. Methodology, accuracy, cost, and where each one fits in race-day planning.

We built this comparison because the Performance Lab Sodium Calculator is one of these tools and we think a side-by-side helps athletes pick the right tool for their situation. Where a competitor does something better than we do, we say so.

Free + Brand-Neutral

Beetroot Pro

The only tool in this comparison that lists pickle juice, bouillon, and table salt as primary sodium sources alongside electrolyte capsules. Transparent math, shareable URLs, no forced account.

Lab-Measured Sodium

Precision Fuel & Hydration

The only tool that offers a genuine in-lab sweat patch with a chloride electrode. $120-200 plus travel to an authorized location. Most accurate sweat sodium concentration available to retail.

Research-Grade

AIS

The institutional foundation. AIS published the Sports Supplement Framework that classifies dietary nitrate as Group A (highest evidence tier). No consumer app, but cited by everyone.

Feature Comparison

Methodology check: claims below reflect each tool's public-facing functionality at the time of writing. Where a tool offers something paid in addition to free, the row indicates the free-tier behavior. Scroll horizontally on mobile.

FeatureBRP CalculatorPF&HLMNTMaurtenAIS
Free public access

AIS resources are public but oriented toward sports dietitians, not direct consumer use.

Email required to use

PF&H Fuel & Hydration Planner asks for account creation to save results.

Personalized inputs (event, weight, climate, sweat history)
Sweat-sodium concentration tiers4 tiers (200-1800 mg/L)4 tiers (similar range)Lab-measured (gold standard)
Hourly breakdown / pacing schedule
Hyponatremia overdrinking warnings
Brand-neutral sodium sources

PF&H, LMNT, and Maurten all recommend their own products as the primary source.

Pre-race sodium loading protocol
Branded PDF download
Shareable URL (no account required)
Save plan to account
Measured sweat rate optionyes (free, weigh-in)paid in-lab testresearch-grade
Lab-grade sweat sodium testyes ($120-200)yes (research)
Heat acclimation protocolcontent onlyyes (research)
Carb fueling integrationyes (cross-tool)yes (in same planner)yes (own products)
Mobile-optimizedyes (native-quality)
Mid-race troubleshooting guidance
YesPartialNo

Tool Profiles

The shorthand for each tool: positioning, what it does well, where it falls short, and the kind of athlete it serves best.

Beetroot Pro® Sodium Calculator

Free, brand-neutral methodology

Built as part of an integrated Performance Lab stack covering sodium, carbs, hydration validation, and heat adaptation. Designed to be shareable, transparent, and to teach the math rather than hide it.

Strengths

  • Math is fully transparent and inspectable: concentration times sweat rate, climate multiplier, replacement fraction
  • Lists pickle juice, bouillon, table salt and salt tabs by name; we do not push a single branded electrolyte
  • Free Hydration Audit tool converts a weigh-in test into a measured sweat rate with one-click handoff
  • Hyponatremia warnings stratified by profile, climate and duration
  • Shareable URLs work without forcing account creation
  • AIS Group A nitrate evidence tier informs the Beetroot Pro stack recommendation

Tradeoffs

  • No lab-grade sweat sodium electrode test; we approximate concentration from visible salt residue
  • Brand recognition is newer than the established players
  • Native mobile app would be the next polish layer (current is responsive web)

Cost

Free

Best for

Endurance athletes who want a credible, evidence-backed plan without a forced product upsell or paywall. Coaches and physiologists who want to see the math.

Precision Fuel & Hydration

Free planner, paid sweat test

The market leader. Built the category and refined the funnel from free questionnaire to in-lab sweat test to coaching consultations to product subscription.

Strengths

  • Mature native-quality mobile app
  • Genuine lab-measured sweat sodium concentration via in-person sweat patch test
  • Best-in-class brand recognition: Olympic and IRONMAN champion endorsements
  • Combined carbs, fluid, sodium and caffeine in a single planner
  • Strong educational content library

Tradeoffs

  • Free planner gates results behind account creation
  • Sodium source recommendations are limited to their own PH 250, 500, 1000, 1500 products
  • Math is not shown; users have to trust the black box
  • Lab test is $120-200 plus travel to an authorized location

Cost

Free planner. $120-200 for the in-person Advanced Sweat Test. Consultations and coaching are tiered higher.

Best for

Athletes who want a measured number from a sweat patch and are happy buying the matching electrolyte products to execute the plan.

LMNT

Salt company with content marketing

Not really a calculator competitor at the endurance-event level. LMNT is a high-sodium electrolyte product (1000 mg sodium per packet) with strong content marketing oriented toward keto, paleo, and general-population sodium intake.

Strengths

  • Brand recognition from podcast saturation (mainstream wellness audience)
  • Excellent content marketing and recipe guides
  • High-sodium single-serve packaging fits salty sweater profiles
  • No paywall, no friction

Tradeoffs

  • No event-specific or hourly-paced calculator
  • One-size-fits-most recommendations (~5,000 mg sodium per day)
  • No hyponatremia warnings or stratification by sweat profile
  • Recommendations always route to their own product

Cost

Free content. Product is $45 for 30 packets (~$1.50 per serving).

Best for

Athletes following keto or low-carb diets who already need higher baseline sodium, and want a simple branded electrolyte without a planning tool.

Maurten

Product configurator for Maurten gels and drinks

A product configurator dressed as a fueling tool. Built around their hydrogel technology (Drink Mix 160, 320, Gel 100). Their tool tells you which of their products to use at which aid station.

Strengths

  • Premium positioning with elite-athlete brand halo (Kipchoge sub-two marathon)
  • Tight integration between tool and product SKUs makes execution easy if you already use Maurten
  • Predictable race-day kit list with no guessing

Tradeoffs

  • Calculator does not surface sodium as a target separate from product selection
  • No sweat profile differentiation
  • No hyponatremia warnings
  • Tool only useful if you are already a Maurten product user
  • Premium product pricing ($60+ per box of gels) limits accessibility

Cost

Free tool. Products are premium-tier ($3-5 per gel, $4-6 per drink mix serving).

Best for

Marathon and ultra athletes already committed to the Maurten product line who want a turnkey execution plan in their preferred ecosystem.

AIS (Australian Institute of Sport)

Research-grade institutional resource

Not consumer software. AIS publishes the Sports Supplement Framework that classifies nitrate as Group A (highest evidence tier). Their sweat-sodium testing is research-grade (sweat patch plus chloride electrode) and is performed in lab.

Strengths

  • Genuine methodological rigor; AIS Group A classification is the credibility lever the entire field cites
  • Free public publications, position statements, and protocols
  • Foundation of much of the underlying science in this category
  • Institutional credibility unmatched by private companies

Tradeoffs

  • No consumer-facing calculator app
  • Resources are PDFs and position statements, not interactive tools
  • Designed for sports dietitians and physiologists, not athletes directly

Cost

Free, but designed for technical users.

Best for

Coaches, sports dietitians, and athletes who want to read the source research and understand the methodological basis of every other tool in this comparison.

Common Questions

Which sodium calculator is most accurate for endurance athletes?

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Accuracy depends on the input quality. The most accurate sodium concentration comes from an in-lab sweat patch test with a chloride electrode (Precision Fuel & Hydration offers this for $120-200). For free tools, accuracy depends on whether you can accurately classify your sweat profile and whether you can validate the body-weight-based sweat rate estimate with a weigh-in test. Beetroot Pro is the only free tool that includes a separate hydration audit to convert a weigh-in test into a measured rate.

Do I need a lab-measured sweat sodium test to plan my race nutrition?

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No. Visible white salt residue on skin or kit after long efforts is the strongest field indicator of above-average sweat sodium concentration. Combining that observation with a 60-minute weigh-in test for sweat rate gets most athletes within 10-15% of their lab-measured numbers. A lab test is most useful for athletes who already cramp at race pace and want to remove every variable.

Is LMNT a calculator?

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No. LMNT is a high-sodium electrolyte product with content marketing about daily sodium intake. They do not have an event-specific or hourly-paced calculator. Their methodology is one-size-fits-most rather than personalized.

What is the difference between Precision Hydration and Beetroot Pro?

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Precision Fuel & Hydration is the market leader with a paid in-lab sweat test and a product line. Beetroot Pro is brand-neutral on sodium sources (we list pickle juice, bouillon, salt tabs, and table salt explicitly), shows the math behind every calculation, and includes a free Hydration Audit tool that approximates the value of the paid sweat test using a weigh-in protocol.

Why does Beetroot Pro list competitor products in the source reference?

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Brand neutrality is a credibility lever. The sodium source reference table lists salt tabs, electrolyte capsules, sports drinks, pickle juice, bouillon, and table salt by function rather than brand. This lets athletes build a plan using whatever sources they already have access to. Beetroot Pro is positioned as the oxygen-efficiency layer on top of an athlete's existing electrolyte strategy, not as a replacement for it.

How does heat acclimation fit in?

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Heat exposure over 10 to 14 days expands plasma volume by roughly 10 to 15%, which lowers core temperature at race pace and reduces sweat sodium concentration. Beetroot Pro is the only tool in this comparison with a free, day-by-day heat acclimation protocol that pairs directly with the sodium calculator's profile tiers.

Try It For Yourself

Run The Beetroot Pro Calculator

Free. No account required. Shareable URL. The math is right there on the page if you want to audit it. We list pickle juice, bouillon, and salt tabs alongside electrolyte capsules, because the best sodium source is the one you will actually use.

Sodium CalculatorHydration Audit