Money Flow Index (MFI): Definition and Formula

Definitions

It uses typical price times volume, classifies each flow by the change in typical price, and maps the ratio to 0 through 100.

With period 14, PMF and NMF are summed over 14 classified flows and MFI = 100×PMF/(PMF+NMF), with explicit zero-sum handling.

Zones such as 20 and 80 are descriptive conventions, not calibrated probabilities.

MFI = 100 × PMF/(PMF+NMF)

LaTeX: MFI = 100 \times \frac{PMF}{PMF+NMF}

Symbol	Meaning	Unit
`PMF`	positive money flow sum	price-volume
`NMF`	negative money flow sum	price-volume

Output unit: 0 to 100

A reviewer computes Money Flow Index from a small OHLCV fixture and checks readiness, units, and edge cases before publication.

Zones such as 20 and 80 are descriptive conventions, not calibrated probabilities.

Money Flow Index (MFI) TradingView · official platform documentation
Supports: preferred label, short definition, technical definition, formula
Limits: Common overbought/oversold zones are descriptive conventions, not probabilities or guarantees.
Money Flow Index technical note TA-Lib · first party technical publication
Supports: preferred label, short definition, technical definition, formula
Limits: A library note does not settle application-specific edge cases or locale wording.
Volume indicators function group TA-Lib · first party technical publication
Supports: preferred label, short definition, technical definition, formula
Limits: Library compatibility does not by itself prove a project's seed, warm-up, or missing-data policy.
Closing Price Investor.gov · official standard
Supports: preferred label, short definition, technical definition, formula
Limits: A close is not automatically an adjusted close and may vary by market session convention.

This record is evidence-reviewed and readable, but not yet promoted to published — it is served noindex,follow and excluded from the sitemap.