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Potassium Replacement Calculator

Work out potassium replacement instantly with clear inputs, formula shown and shareable results.

About Potassium Replacement Calculator

Uses the widely quoted rule that each 0.3 mmol/L fall in serum potassium reflects roughly a 100 mmol total body deficit, then converts that into infusion time or oral doses.

Formula

Potassium deficit

Deficit (mmol) = (target K - current K) / 0.3 x 100; hours = deficit / infusion rate

Worked example

With the default values below, Potassium Replacement Calculator returns Estimated total body potassium deficit of 333. Change any input above and every figure here is recalculated in your browser.

Inputs used

Current serum potassiumaccepts 1.5–5 mmol/L
3 mmol/L
Target serum potassiumaccepts 3–5 mmol/L
4 mmol/L
Planned infusion rateaccepts 2–20 mmol/h
10 mmol/h

Results

Estimated total body potassium deficit
333 mmol
Hours at the planned rate
33.3 h
Equivalent 20 mmol oral doses
16.7

Step by step

  1. 1Values used
  2. 2Potassium deficit
  3. 3Estimated total body potassium deficit= 333 mmol
  4. 4Hours at the planned rate= 33.3 h
  5. 5Equivalent 20 mmol oral doses= 16.7

Assumptions and limits

  • The result is derived only from the 3 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
  • Figures are rounded for display to 1 decimal place, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
  • Educational estimate only. Not a substitute for professional clinical judgement, and must not be used to make treatment or dosing decisions.
  • This is an estimate for general information and not professional medical advice. See the full disclaimer for the limits that apply to this kind of calculator.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Educational estimate only. Not a substitute for professional clinical judgement, and must not be used to make treatment or dosing decisions.

Frequently Asked Questions

What infusion rate is safe?

Peripheral infusions are commonly limited to 10 mmol/h; faster rates need central access and cardiac monitoring.

Is the rule accurate?

It is a rough guide only; acid-base state and insulin shift potassium between compartments and change the relationship.

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