Volume and average volume: calculation and reading

Average volume is a moving average of volume, used to judge whether today’s volume is large or small relative to the recent past.

Updated：2026-11-08

Volume

Volume is the quantity traded over a period; in Taiwan the unit is the “lot” (1 lot = 1,000 shares). The bars below the candlesticks are each day’s volume.

Average volume

N-day average volume = the simple average of volume over the last N days. By default this site draws two average-volume lines, 10 days and 20 days.

How to use it

• Compare the day’s volume with the average: above average means more active than the recent past, and below average means quieter than the recent past. The “volume ratio” style conditions on the Screener page use this idea: how many times its average volume today’s volume is.
• Volume is measured in lots, and different stocks have different share capital and free float, so volume cannot be compared directly across stocks; use each stock’s own average volume as the baseline.

Limits

Volume is affected by events such as ex-dividend dates, index rebalancing days and major news, so a single day of heavy or light volume does not necessarily mean the trend has changed; it describes trading that has already happened and does not predict the future.

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