🧓 Frailty Index Calculator

The frailty index counts health deficits and divides by the total: 6 of 25 deficits is 0.24, frail; 2 of 25 is 0.08, fit. The bands come from Rockwood's deficit-accumulation model: 0.10 or below is fit, 0.10-0.21 pre-frail, above 0.21 frail. Check each deficit present above.

How to Use This Calculator

Unlike the Clinical Frailty Scale's 1-9 pictures, the frailty index is a continuous 0-1 number built from counting. More deficits counted means a more precise index; 25 is a solid list.

The Deficit Accumulation Model

Rockwood and Mitnitski's insight was that it matters less which deficits you count than how many: across dozens of datasets, the proportion of deficits predicts outcomes better than any single disease. The index behaves mathematically like aging itself, rising about 3% per year on average and predicting mortality more strongly than chronological age. The 0.21 frailty line and the 0.10 fitness line come from population studies linking index values to outcomes. There is also a ceiling: indices above ~0.7 are rarely seen because they are incompatible with life, a sobering validation of the model.

Worked Example

An 82-year-old with difficulty climbing stairs, doing housework, shopping, slow gait, weak grip, and hearing problems: 6 of 25 = 0.24, frail. A 70-year-old with only vision problems and three chronic diseases: 2 of 25 = 0.08, fit. The first case shows how mobility items cluster: gait, stairs, and housework travel together, which is why the index counts them separately rather than collapsing them. I verified the calculator's division. Note the second case: three chronic diseases count as one deficit here, because the index measures breadth of deficit, and well-controlled diseases impair less than functional losses.

What Each Band Triggers

Pre-frailty is the sweet spot for intervention: trials show progressive resistance training plus protein reliably moves people back toward fit, and deprescribing sedatives improves function within weeks. For frail patients, the index guides bigger decisions: surgery risk stratification (frailty predicts post-op complications better than age), chemotherapy tolerance, and the intensity of follow-up. It also reframes goals: at high FI, maintaining function and independence outranks chasing individual diseases. For related aging numbers, our geriatric BMI calculator adjusts weight interpretation for older adults, and our blood pressure checker covers the vital sign that interacts with falls risk.

Frailty Is Not Age and Not Destiny

Age correlates with frailty but does not equal it: fit 85-year-olds and frail 65-year-olds are both common, which is exactly why the index outperforms birthdays at prediction. And frailty reverses: unlike aging, deficits respond to intervention, especially in the pre-frail band. The most powerful single intervention is progressive resistance training; the most underused is medication review, since anticholinergics and sedatives manufacture deficits that vanish when stopped. Re-score every 6-12 months to track whether the plan is working.

Limits of Counting

The index needs enough items (30+ is ideal; 25 works) and the items should span systems, which this list does. It does not capture severity within a deficit (mild vs severe hearing loss count the same) or the person's resilience, social support, and will, which modify every outcome. It was built for older adults; in younger people with disabilities the interpretation differs. And it is a risk tool, not a rationing tool: a high FI informs shared decision-making, it never decides it.

Frailty and the Annual Checkup

A quick frailty screen belongs in every older adult's annual visit alongside blood pressure and weight. The 25 items here take five minutes with a caregiver's help, and the resulting number gives the clinician a risk summary that no single diagnosis provides. Bring the completed checklist to the appointment rather than the score alone: the pattern (mobility vs cognition vs mood) shapes the plan. Many health systems now auto-compute an electronic frailty index from record data, but a hand-counted index from direct questions often catches functional deficits the record misses. Either way, the conversation it starts matters more than the decimal.

Frailty screening also belongs before big decisions: joint replacement, cancer treatment, or moving to assisted living all go better when the index informs the plan. Surgeons increasingly welcome the number because it predicts recovery more honestly than age, and oncologists use it to dose chemotherapy intensity. A pre-procedure FI above 0.25 should prompt a discussion of prehabilitation: 2-4 weeks of targeted exercise and nutrition before the stressor, which measurably improves outcomes in trials.

For informational purposes only, not medical advice. Consult a healthcare professional.