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Corrected Potassium Calculator

Enter the measured potassium and arterial pH to get the pH-corrected potassium.

How it is calculated

The tool moves a measured potassium to what it would be at the reference pH of 7.4: K_corrected = K + 0.6 × ((pH − 7.4) ÷ 0.1). K is the measured serum potassium in mEq/L and pH is the arterial pH from the same sample. The pH offset, pH − 7.4, is shown too. Each 0.1 pH unit away from 7.4 shifts the potassium by 0.6 mEq/L, and the direction follows the sign: a pH below 7.4 gives a negative offset and lowers the corrected value, a pH above 7.4 raises it. Both inputs must be above zero. The factor of 0.6 is a rough bedside rule, not an exact constant, so the result is an estimate to read together with the clinical picture.

Worked example

A blood sample shows potassium 5.8 mEq/L at an arterial pH of 7.2. The offset is 7.2 − 7.4 = −0.20, which is two steps of 0.1. The adjustment is 0.6 × (−0.20 ÷ 0.1) = −1.2 mEq/L. The corrected potassium is 5.8 − 1.2 = 4.60 mEq/L. Much of the high reading in this sample is therefore explained by the acidic pH rather than by a true excess of potassium.

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Common mistakes

  • Adding the correction when pH is low: the sign is built into the formula, so at pH 7.2 the value goes down, not up.
  • Entering the pH of a venous sample while treating it as arterial pH, or mixing values drawn at different times: potassium and pH must come from the same sample.
  • Using the result as a replacement for the measurement: the 0.6 factor is approximate, and the corrected figure is only a sanity check.
  • Typing the potassium in the wrong unit or with a misplaced decimal: the field expects mEq/L, such as 5.8, not 58 or 0.58.

About this calculator

Blood pH shifts change how potassium moves between blood plasma and body cells, so a measured serum potassium level can look artificially high or low if a patient's blood is more acidic or alkaline than the normal reference pH of 7.4. Corrected potassium adjusts the measured value back to what it would likely read at pH 7.4, using K_corrected = measured K + 0.6 × ((pH − 7.4) / 0.1) — for every 0.1 drop in pH below 7.4 (acidosis, which makes the measured value look too high), potassium is corrected downward by 0.6 mEq/L, and for every 0.1 rise above 7.4 (alkalosis) it is corrected upward by 0.6 mEq/L.

This correction is used in clinical chemistry and critical care, where a patient's arterial blood gas and electrolyte panel are often drawn together, so clinicians can tell whether an abnormal potassium reading reflects a true electrolyte imbalance or is simply an artifact of acidosis or alkalosis shifting potassium across cell membranes. It's a bedside sanity check rather than a replacement for clinical judgment, and any corrected value should always be interpreted alongside the patient's full clinical picture.

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