Sodium to Potassium Ratio Calculator (Na:K Balance)
Your daily sodium-to-potassium ratio by mass and molar, compared with US (NASEM / Dietary Guidelines), WHO and American Heart Association targets: salt equivalent, mmol, percent of each limit or target, how much potassium to add or sodium to cut to reach a 1:1 molar ratio, and potassium-rich foods.
How it works
Mass ratio = sodium mg ÷ potassium mg · Molar ratio = (sodium mg ÷ 22.99) ÷ (potassium mg ÷ 39.10) = mass ratio × 1.70 · Salt (g) = sodium mg ÷ 393.4 · Potassium for a 1:1 molar ratio = sodium mmol × 39.10 mg
Blood pressure depends on the balance of sodium and potassium, not just on salt. Potassium helps the kidneys excrete sodium and relaxes blood-vessel walls, and in cohort studies a lower sodium-to-potassium ratio predicts lower blood pressure and fewer strokes and heart attacks better than either mineral alone. The calculator shows the ratio two ways. The mass ratio uses the milligrams on food labels. The molar ratio compares numbers of atoms (sodium 22.99 g/mol, potassium 39.10 g/mol), which is how studies and the WHO express it; the WHO intake goals of under 2,000 mg sodium (87 mmol) and at least 3,510 mg potassium (90 mmol) work out to a molar ratio of about 1. A molar ratio of 1 is a mass ratio of about 0.59. Typical US and European diets have a molar ratio of 2 or more. You can enter sodium as mg, g, grams of salt or mmol and potassium as mg, g or mmol, and compare with the US limits (sodium under 2,300 mg; potassium Adequate Intake 3,400 mg for men and 2,600 mg for women, different in pregnancy, breastfeeding and the teen years), the WHO goals or the American Heart Association ideal of 1,500 mg sodium. When your ratio is above 1 the calculator shows how much potassium to add, or sodium to cut, to reach 1:1. Food-record estimates are rough; a 24-hour urine test is the most accurate way to measure intake.
Worked example
Default: 3,400 mg sodium and 2,600 mg potassium, a man (US targets). Mass ratio = 3,400 ÷ 2,600 = 1.31. In millimoles: 3,400 ÷ 22.99 = 147.9 mmol sodium and 2,600 ÷ 39.10 = 66.5 mmol potassium, so the molar ratio = 147.9 ÷ 66.5 = 2.22, high and typical of Western diets. Sodium is 148% of the 2,300 mg limit (1,100 mg over) and potassium 76% of the 3,400 mg Adequate Intake (800 mg short). The sodium equals 8.6 g of salt, about 1.4 teaspoons. A 1:1 molar ratio would need about 5,783 mg of potassium at this sodium intake, or sodium cut to about 1,529 mg at this potassium intake; in practice a mix of both, such as 2,300 mg sodium and 3,900 mg potassium, gets close.
Sources: CDC: Sodium and potassium · WHO: Guideline on sodium intake for adults and children (2012) · WHO: Guideline on potassium intake for adults and children (2012) · NIH Office of Dietary Supplements: Potassium fact sheet
Frequently asked questions
What is a good sodium-to-potassium ratio?
The WHO goals (under 2,000 mg sodium and at least 3,510 mg potassium) correspond to a molar ratio of about 1 or less, which is about 0.6 by mass. Studies link ratios at or below 1 (molar) with lower blood pressure and cardiovascular risk; most Western diets are around 2 or higher.
How much sodium and potassium do I need per day?
US guidance is under 2,300 mg of sodium for everyone 14 and older and an Adequate Intake of potassium of 3,400 mg for adult men and 2,600 mg for adult women (2,900 mg in pregnancy, 2,800 mg while breastfeeding). The WHO advises under 2,000 mg sodium and at least 3,510 mg potassium for adults; the American Heart Association sets an ideal of 1,500 mg sodium.
How do I convert salt to sodium?
Salt (sodium chloride) is about 39.3% sodium by weight, so 1 g of salt has about 393 mg of sodium and 1 teaspoon (about 6 g) has about 2,360 mg. To go from sodium to salt, divide the milligrams of sodium by 393.
Why show a molar ratio too?
Sodium atoms are lighter than potassium atoms (23 vs 39 g/mol), so the same milligrams contain 1.7 times as many sodium atoms. The body handles the minerals atom for atom, so research and the WHO use the molar ratio; the mass ratio is easier to read from labels.
What foods are high in potassium?
Beans and lentils (about 600–730 mg per cooked cup), potatoes (about 610 mg in a medium baked potato), orange juice (about 500 mg per cup), bananas (about 420 mg), milk, yogurt, salmon, tomatoes and leafy greens. Two or three extra servings of these foods add roughly 1,000 mg a day.
Can too much potassium be harmful?
From food, rarely, if your kidneys work normally. People with kidney disease, or who take ACE inhibitors, ARBs, potassium-sparing diuretics or potassium supplements, can develop high blood potassium; check with a clinician before using salt substitutes or supplements.
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Educational estimate only, not medical or dietary advice. If you have high blood pressure, kidney disease or heart failure, or take medicines that affect potassium, ask your clinician or a registered dietitian before changing your sodium or potassium intake.