Potassium-to-Sodium Ratio Calculator

Understanding the potassium-to-sodium ratio calculator — concept and principle

Blood pressure depends not only on how much sodium you eat but on the balance between sodium and potassium. This calculator compares your daily potassium and sodium intakes as a weight ratio and as a molar ratio (the ratio of the number of atoms), and sets them against the World Health Organization targets.

More potassium (fruit, vegetables, beans) or less sodium both push the ratio up.

How it is calculated

K : Na ratio = potassium (mg) ÷ sodium (mg)
Molar ratio = (potassium ÷ 39.1) ÷ (sodium ÷ 23)

Both inputs are in milligrams per day. Dividing by the atomic mass (about 39.1 for potassium, 23 for sodium) converts milligrams to millimoles, so the molar ratio compares numbers of ions, which is how physiologists usually express it.

The principle

Sodium tends to hold water in the circulation and raise blood pressure, while potassium helps the kidneys excrete sodium and relaxes blood vessel walls. Raising potassium lowers blood pressure, especially in people who eat a lot of salt. The WHO recommends at least 90 mmol of potassium (3,510 mg) and less than 2,000 mg of sodium a day. Dividing these gives a weight ratio of about 1.75 and a molar ratio of about 1.0, so meeting both targets means eating at least as many potassium ions as sodium ions.

Worked example

Default inputs: potassium 3,000 mg, sodium 3,200 mg.
Weight ratio = 3,000 ÷ 3,200 = 0.9375, shown as 0.94.
Potassium = 3,000 ÷ 39.1 ≈ 76.7 mmol; sodium = 3,200 ÷ 23 ≈ 139.1 mmol.
Molar ratio = 76.7 ÷ 139.1 ≈ 0.551, shown as 0.55.

The calculator shows a K : Na ratio of 0.94 and a molar ratio of 0.55.

Each point is the calculator re-run with only “Sodium (mg)” changed; the gold point is the default example. Change the inputs above and this chart follows your numbers.

Sodium (mg)	K : Na ratio
800	3.75
1,600	1.88
2,400	1.25
3,200	0.94
4,000	0.75
4,800	0.63
6,400	0.47

How to read the result

A higher ratio is better. A weight ratio of about 1.75 or more (molar about 1 or more) matches the WHO targets. Typical diets based on processed food often have a molar ratio well below 1, as in the example, where there are almost twice as many sodium ions as potassium ions. You can improve the ratio from both sides: cut sodium from processed foods, soups and sauces, and add potassium from vegetables, fruit, beans, potatoes, yoghurt and nuts.

Common mistakes

Mixing units, for example potassium in mg and sodium as grams of salt; convert salt to sodium first.
Counting only one meal; the ratio is meaningful over a whole day or several days.
Assuming a good ratio cancels very high sodium; the absolute sodium target still applies.

Keep in mind: This tool is general information, not a diagnosis. People with kidney disease, or who take medicines such as ACE inhibitors, angiotensin receptor blockers or potassium-sparing diuretics, can develop dangerously high blood potassium and should not raise potassium or use salt substitutes without medical advice.

Frequently asked questions

Which foods are high in potassium?

Potatoes, beans and lentils, leafy greens, tomatoes, bananas, dried fruit, milk and yoghurt are good sources.

Are potassium-based salt substitutes a good idea?

For healthy people they can lower sodium and raise potassium, but they are risky for people with kidney problems or on the medicines listed above.

Sources: World Health Organization. Guideline: Potassium intake for adults and children. Geneva: WHO, 2012. · World Health Organization. Guideline: Sodium intake for adults and children. Geneva: WHO, 2012.

Checked 8 Nov 2026. Published formulas cited on the page. For information only — not medical advice.

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