BIAS (bias ratio): calculation and reading

The bias ratio is the distance between the closing price and a moving average, expressed as a percentage.

Updated：2026-11-08

Calculation

N-day bias ratio = (close − N-day simple moving average) ÷ N-day simple moving average × 100 (%). By default this site shows three lines at once: 6, 12 and 24 days.

• Positive: the close is above the moving average; the larger the value, the farther from the average.
• Negative: the close is below the moving average.
• 0: the close is exactly equal to the moving average.

How to read it

• The shorter the period, the more the bias ratio swings; the longer the period, the smoother it is.
• Every stock has its own habits of fluctuation, so there is no universal standard for “how large is large”; it is usually compared with that stock’s own historical range. The thresholds of the “bias ratio” condition on the Screener page can also be adjusted.

Limits

The bias ratio only describes how far price is from the moving average. It does not indicate direction and does not predict that price will return to the average. Use adjusted prices for the calculation; otherwise ex-dividend gaps distort the moving average.

This article only explains the calculation and how to read a chart. It is not investment advice.