What is the Piotroski F-Score?
A 0 to 9 quality score from Joseph Piotroski's 2000 paper, built from nine binary financial-strength tests. The cleanest single quality overlay you can layer on a value-screened cohort.
The Piotroski F-Score scores a stock 0 to 9 by giving one point for each of nine binary financial-strength tests: positive net income, positive operating cash flow, OCF exceeding net income, ROA increasing, leverage decreasing, current ratio improving, no equity issuance, gross margin improving, and asset turnover improving. F-Scores of 8 or 9 historically delivered ~7.5 percentage points annual outperformance over low-F-Score peers in the cheapest value cohort.
The nine tests
Piotroski organised the nine binary tests into three categories. Profitability: net income positive, operating cash flow positive, OCF exceeding net income (signaling earnings backed by cash), and ROA improving over the prior year. Leverage and liquidity: long-term debt ratio decreasing, current ratio increasing, and no new equity issued in the period. Operating efficiency: gross margin improving and asset turnover improving.
Each test that passes earns one point; the total ranges from 0 (worst) to 9 (best). The construction is deliberately binary so the score is robust to small differences in accounting interpretation: either ROA went up or it didn't.
How it's used in practice
The original paper applied the F-Score to stocks in the top quintile of book-to-market (the cheapest 20% on a traditional value metric). Within that already-cheap cohort, the high-F-Score names outperformed the low-F- Score names by approximately 7.5 percentage points annually over 1976 to 1996. The signal was robust to size, time period, and exchange.
In invest-like, the F-Score appears inside the Graham defensive-investor framework and the Greenblatt Magic Formula deal-breaker overlay. It's one of three academically-validated quality screens layered on top of the multi-framework consensus.
Limitations
Survivorship and look-ahead bias affect the original study; the in-sample window may not generalise to all regimes. The F-Score is most informative within an already-screened value cohort; applied indiscriminately, the signal is muted. The binary construction means a firm just barely crossing each threshold earns full points alongside a firm comfortably above; the score cannot distinguish "barely improving" from "substantially improving".
Frequently asked questions
What is the Piotroski F-Score?
A 0 to 9 integer quality score from Joseph Piotroski's 2000 paper. Each point comes from passing a binary financial-strength test across profitability, leverage, and operating efficiency.
What's a good F-Score?
8 or 9 is high-quality; 0 to 2 is weak. The Piotroski sample found that within the cheapest 20% by book-to-market, the high-F-Score quintile outperformed the low quintile by roughly 7.5 percentage points annually.
How does invest-like use the F-Score?
Inside the Graham defensive-investor framework and the Greenblatt Magic Formula deal-breaker overlay, as one of three academic quality screens layered on the multi-framework consensus.
Related
- Working papers - the consensus screen methodology that incorporates the F-Score.
- Methodology hub
- Benchmarks - the original Piotroski 1976 to 1996 sample as an academic baseline.
- What is the Magic Formula?
Educational only. invest-like is not a registered investment adviser; nothing on this page constitutes personalised investment advice.