What is a frailty index?

A frailty index (FI) measures the proportion of health deficits present in an individual from a standardized list. It is calculated as the number of deficits present divided by the total number of deficits assessed. FI values range from 0 (no deficits) to 1 (all deficits present).

What score indicates frailty?

In this educational implementation, scores below 0.10 are labeled robust, 0.10–0.24 pre-frail, 0.25–0.39 frail, and 0.40 or higher severely frail. Cutoffs vary among published frailty indices and must be interpreted with the exact deficit set used.

How is this different from the Clinical Frailty Scale (CFS)?

The Clinical Frailty Scale (CFS) is a single 9-point judgment-based score, while the deficit-accumulation Frailty Index uses a checklist of specific health items. The FI is more granular and sensitive to small changes in health status over time.

Can this tool replace a clinical assessment?

No. This calculator is for informational and educational purposes only. A qualified clinician should conduct a thorough assessment and interpret results in the context of the individual patient's full medical history.

Why does this frailty index use 31 deficits?

Deficit-accumulation indices commonly use at least 30 age-associated items. This educational checklist contains 31; it is not interchangeable with a separately validated instrument using a different item set.

Does a higher number of deficits always mean worse outcomes?

Generally yes — higher FI scores are consistently associated with greater risk of falls, hospitalization, institutionalization, and mortality in large population studies. However, individual variation exists and the FI should complement, not replace, clinical judgment.

Frailty Index Calculator

Select health deficits across multiple domains to calculate a frailty index score and assess vulnerability in older adults.

Health Deficit Checklist

Results

0.00

Frailty Index Score

0 deficits of 31 assessed

0.00 0.25 0.40 1.00

Frailty Category

Robust

No significant deficits identified. Maintain healthy lifestyle habits.

Score Reference

< 0.10	Robust
0.10 – 0.24	Pre-frail
0.25 – 0.39	Frail
≥ 0.40	Severely Frail

For educational use only. Results do not constitute medical advice. Consult a qualified clinician for formal assessment.

Summary

The Frailty Index (FI) quantifies vulnerability by counting the proportion of health deficits present across multiple domains. This educational 31-item implementation labels values of 0.25 or higher as frail and 0.40 or higher as severely frail; published frailty indices use differing item sets and cutoffs, so results are not interchangeable.

How it works

Review each health deficit item across the five domains.
Check all deficits that apply to the individual being assessed.
The calculator counts the number of deficits present.
The frailty index score is computed as deficits present divided by total deficits assessed.
Interpret the score using the four frailty categories shown in the results panel.
Use the results to guide clinical decision-making or care planning.

Use cases

Pre-operative frailty screening for elderly surgical candidates.
Geriatric care planning and prioritization of interventions.
Research studies measuring frailty in older populations.
Monitoring change in frailty status over time with repeat assessments.
Identifying individuals at high risk for falls, hospitalization, or mortality.
Communicating vulnerability risk to patients and families.
Supporting multidisciplinary team discussions about care goals.
Teaching clinical staff about the deficit accumulation model of frailty.

Frequently Asked Questions

Last updated: 2026-05-23 · Reviewed by Nham Vu