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Frailty Index Calculator

Work out frailty index instantly with clear inputs, formula shown and shareable results.

About Frailty Index Calculator

Divides the number of health deficits present by the number assessed, the cumulative deficit model of frailty described by Rockwood and Mitnitski.

Formula

Cumulative deficit frailty index

Frailty index = deficits present / deficits assessed; commonly quoted bands are under 0.12 fit, 0.12-0.24 vulnerable and over 0.24 frail

Worked example

With the default values below, Frailty Index Calculator returns Frailty index of 0.200. Change any input above and every figure here is recalculated in your browser.

Inputs used

Deficits presentaccepts 0–80
8
Deficits assessedaccepts 5–80
40

Results

Frailty index
0.200
Deficits present
20.0%
Band
Pre-frail or vulnerable

Step by step

  1. 1Values used
  2. 2Cumulative deficit frailty index
  3. 3Frailty index= 0.200
  4. 4Deficits present= 20.0
  5. 5Band= Pre-frail or vulnerable

Assumptions and limits

  • The result is derived only from the 2 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 3 decimal places, 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

How many deficits are needed?

At least 30 to 40 items give a stable index; the exact list matters less than the count and breadth.

Is there a practical ceiling?

Empirically the index rarely exceeds about 0.7, a submaximal limit seen across many populations.

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