What is volume in trading?

One bar, one number

The histogram under the price has one bar for every candle, and each bar counts what was traded during that candle. Shares on a stock, contracts on a future, lots on a currency pair. Not money, not orders, and not the number of people involved.

• It belongs to one period. Change the timeframe and every bar changes with it, exactly as the candles do. A five minute bar and a daily bar count different spans of the same market.
• It has no direction. Every trade has a buyer and a seller, so the same number sits on both sides. There is no buying volume and no selling volume in this histogram. A platform that colours the bar green or red is colouring it by where the candle closed, and that adds nothing you could not already see.
• The last bar is not finished. On a live chart it grows until the period ends, for the same reason the last candle has not closed. Comparing it to the finished bars beside it compares half a period with whole ones.

That is the whole object. Everything else on this page is about what to compare it to, because a volume bar on its own says nothing at all.

There is no big volume in the abstract

Forty million shares is not a lot and it is not a little. It is a number, and it only becomes a reading once you know what this market usually does at this hour on this timeframe.

The guide on the ATR already makes this move for range: the only meaningful comparison is a market against its own recent self. Volume works the same way, and the reading that does it has a name.

• Relative volume. This bar against the average of the same bar over the last several days. Above one is busier than usual, below one is quieter. Most platforms will draw it for you.
• The shape of the day. Volume is not flat between the open and the close. It is heavy at the open, thin through the middle, and heavy again into the close. Comparing ten in the morning with one in the afternoon compares two different questions, which is why the average has to be taken hour against the same hour.

The hours have that rhythm because of who is awake, which is covered in the guide on trading sessions.

The three comparisons that are not comparisons

Three habits produce a number that looks like a reading and is not one.

• One market against another. A share count and a lot count are not the same unit, and neither is a tick count. Nothing useful comes out of the ratio.
• One timeframe against another. A bar that covers five minutes and a bar that covers a day are both called volume and measure different spans. Compare like with like or do not compare.
• A normal day against a day that is not one. A half session, an expiry, an index rebalance and a holiday all produce bars that belong to a different population. They are worth knowing about and they are not worth averaging in.

What a big bar does not prove

A large bar says a lot of business was done. It does not say which way it went, and it does not say who did it.

• It is not direction. A spike under a wide up candle and a spike under a wide down candle are the same bar. The direction is in the candle, and it was already visible without the histogram.
• It is as often an ending as a beginning. The heaviest bar of a move is frequently the one where everyone who wanted in finally got in, which leaves nobody to keep pushing.
• It does not arrive early. The bar closes at the same instant the candle closes. It is one more description of that instant, not a confirmation that comes first. What confirms a break on this site stays what it was: a close beyond the level, and then the retest, as set out in the guide on market structure.
• It does not name a participant. One large bar can be a fund rebalancing, an option expiry or an index change, none of which has an opinion about tomorrow.

What the histogram genuinely adds is a second measurement of the same moment, taken from something other than price. That is why the guide on confluence counts it as its own family, and it is also why a volume reading that merely agrees with the candle is not a separate reason.

Where the bar is not really volume

The bar is only as real as the market behind it, and that changes with the venue.

• Stocks and futures. There is a central exchange, it publishes a traded figure, and the bar means what it says.
• Spot forex. There is no central exchange, so there is no true volume. What the platform draws is how many price updates arrived from one broker, counted off movement rather than off trades. It moves with real activity and it is not the same measurement.
• Crypto. Real, and real per venue. A chart from one exchange describes that exchange, and the same coin elsewhere will not draw the same histogram.

This is the same limit the guides on VWAP and the volume profile carry, for the same reason: both are built from this number.

Questions people ask

What is a good volume level?

There is no level. The number is in units of whatever you are looking at, so it cannot be compared across markets, and it cannot be compared across timeframes either. The only useful reading is this bar against the same bar on recent days.

Does high volume mean the price will go up?

No. Every trade has a buyer and a seller, so a busy bar says a lot of business was done and nothing about direction. The direction is in the candle above it.

Does volume confirm a breakout?

It describes it. The bar closes at the same moment the candle closes, so it never arrives before the close you were already waiting for. A break on a quiet bar is worth less attention than a break on a busy one, and neither is a confirmation on its own.

Does volume work on forex and crypto?

On crypto, yes, one exchange at a time. On spot forex there is no true volume, because there is no central exchange: what you see is tick activity from a single broker, which moves with real trading without being it.

Reading the bars that are already on the chart

Trading AI reads a photo or a screenshot of any chart and returns a volume reading when the histogram is visible in the image, alongside the market structure, the key levels, the momentum and a full trade plan. What is not in the frame does not exist for the model, so a chart with the volume pane switched off cannot produce one.

Where the business was done, rather than how much of it there was in this candle: What is a volume profile?

The same number used as a weight, to produce a price rather than a count: What is VWAP?

The four prices the bar sits under, and what they record: How to read a candlestick chart.

This page is educational. It is not financial advice, and nothing here is a recommendation to buy or sell anything.