Calculate the sodium to potassium ratio (Na:K) by mass or molar amount from mg or g of each, with the K:Na ratio, or find potassium for a target ratio.

Use elemental sodium and potassium from the same serving, period or laboratory sample.

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Sodium to Potassium Ratio Formula

The following formula gives a mass ratio when S and P are elemental masses in the same unit, or a molar ratio when both are molar amounts in the same unit. Potassium must be positive. For masses in mg, molar Na:K = (sodium/22.98976928)/(potassium/39.0983), using adopted nominal atomic weights.

SPR = S / P
  • Where SPR is the Sodium to Potassium Ratio (sodium:potassium)
  • S is the total amount of sodium
  • P is the total amount of potassium

Divide sodium by potassium on the same sample and unit basis. A ratio below 1 means less sodium than potassium on the selected mass or molar basis; it is not a health classification. A 1:1 molar Na:K ratio is approximately 0.588:1 by mass, while 1:1 by mass is approximately 1.701:1 molar. Zero sodium gives a zero Na:K ratio, but its K:Na reciprocal is undefined. The inverse solve requires positive sodium and a positive chosen target.

Why Sodium and Potassium Amounts Both Matter

Sodium and potassium both matter, but their quotient cannot replace the absolute amounts. For example, 200 mg sodium with 350 mg potassium has the same mass ratio as 2,000 mg with 3,500 mg. A ratio calculation alone cannot establish nutritional adequacy, diagnose blood-electrolyte imbalance or predict an individual cardiovascular outcome. The calculator reports the entered amounts alongside both ratio bases.

The Evolutionary Baseline: How Far Modern Diets Have Shifted

A single reconstructed ancestral intake ratio is not a clinical benchmark for a modern individual. Comparisons need the same mass or molar basis and comparable dietary measurement methods. This calculator does not assume an evolutionary optimum or infer a personal target from historical food patterns.

What a Healthy Sodium to Potassium Ratio Looks Like

WHO adult dietary guidance discusses sodium below 2,000 mg/day and potassium of at least 90 mmol/day, about 3,510 mg/day. Its potassium guideline does not establish an optimal Na:K ratio; meeting both guidelines produces an approximately 1:1 molar ratio. As unit arithmetic, exactly 2,000 mg sodium and 3,510 mg potassium give about 0.570:1 by mass and 0.969:1 molar. These population recommendations do not set a personal target or a urinary cutoff.

Health Consequences of a High Na:K Ratio

WHO identifies high sodium intake as a contributor to higher blood pressure and notes that potassium can moderate this effect. Interpretation still depends on absolute intake and the individual situation. A calculated ratio does not measure blood pressure or establish the presence or severity of hypertension.

This arithmetic tool does not estimate stroke, diabetes, cognitive or bone-disease risk. Statistical associations in a defined study population cannot be converted into an individual diagnosis or a universal ratio cutoff here. Use an appropriate clinical assessment for health decisions.

Urinary Na:K Ratio as a Clinical Measurement Tool

The urinary mode calculates a ratio from supplied laboratory amounts; it does not estimate urinary excretion from a dietary record. Use sodium and potassium from the same urine sample or collection period with compatible mass units, and retain the laboratory method and ratio basis. Spot and 24-hour results are not interchangeable by assumption. No urinary risk cutoff, treatment-response prediction or medication recommendation is applied.

Population Data: Where Most People Stand

Population comparisons require a named dataset, date, age group, dietary or urinary method, and mass or molar basis. Ratios from unlike methods cannot be compared directly, and a group average does not establish an individual result. This calculator supplies no population percentile or diagnostic classification.

Foods That Move the Ratio in the Right Direction

For a fixed potassium amount, lowering sodium lowers Na:K; for fixed sodium, increasing potassium also lowers the arithmetic ratio. Food amounts vary by serving and preparation, so use current food-composition or label values. NIH lists potassium food sources and safety considerations. A smaller ratio alone does not prove a diet is appropriate, and this calculator does not recommend potassium supplements or salt substitutes.

Special Populations and Ratio Considerations

Kidney disease and medicines such as ACE inhibitors, ARBs and potassium-sparing diuretics can impair potassium excretion and increase hyperkalemia risk. Standard intake references may not apply in these circumstances. Discuss substantial potassium-intake changes, supplements or potassium-containing salt substitutes with the treating clinician. The chosen-ratio result is a mathematical amount, not a safe dose or a medication instruction.