Delta and cumulative delta.

Every trade has a buyer and a seller, so the useful question is not how much was bought but who crossed the spread. When a buyer sends a market order and pays the ask, the trade is counted as buying volume. When a seller sends a market order and hits the bid, it is counted as selling volume.

Delta for a bar is simply:

Delta = volume traded at the ask - volume traded at the bid

A positive delta means aggressive buyers did more volume in that bar; a negative delta means aggressive sellers did. Delta can be calculated per price level, as on a footprint chart, or per bar, which is how most delta histograms show it.

Cumulative volume delta keeps a running total. Each new bar's delta is added to the previous total, and the result is usually drawn as a line or as candles in a pane under the price chart. Most platforms reset it at the start of each session so that one day's total does not drown out the next; some let you anchor it to a point you choose.

Illustrative example: if three bars print deltas of +200, -50 and +100 contracts, the cumulative delta after the third bar is +250. The level of the line matters less than its direction and how it compares with price.

Confirmation. Price making higher highs while CVD also makes higher highs suggests aggressive buyers are driving the move. The same in reverse for a decline. Traders often treat this as a sign that the trend has participation behind it.

Divergence. Price makes a new high but CVD makes a lower high. Fewer aggressive buyers are willing to pay up at the new price, which can warn that the move is tiring. A bullish divergence is the mirror image at a low. Divergences are warnings, not signals on their own: they can persist through a strong trend.

Absorption. CVD falls sharply while price holds flat or rises. Aggressive sellers are hitting the bid, but passive buyers with limit orders are taking everything. When the selling stops, price can move quickly the other way. This is one of the reasons traders watch delta at important levels such as the prior day's low or the VWAP.

Effort against result. A bar with a large delta but a small price change shows a lot of effort for little result. A bar with a small delta and a large move shows price travelling easily, often because liquidity was thin.

Illustrative scenario, not a trading rule. A market rallies through the morning. Price makes a high, pulls back, then pushes to a slightly higher high in the early afternoon.

• On the first push, CVD rises steeply with price. Aggressive buyers are clearly paying up, and the move has participation.
• On the pullback, CVD dips only a little while price falls further. Selling is not especially aggressive; the drop looks more like buyers stepping back than sellers attacking.
• On the second push to a new high, CVD barely rises and stays below its morning peak. That is a bearish divergence: price is higher, but fewer aggressive buyers came with it.

A trader reading this would not short on the divergence alone. They would note it as a warning and wait for something more, such as price failing back below the morning high, a break below VWAP, or heavy selling showing up on the footprint. If instead price keeps grinding higher and CVD eventually makes a new high too, the warning is cancelled.

The lesson is the same across markets: CVD is a way of asking whether price moved because someone pushed it, or because nobody stood in the way.

• It depends on trade classification. Delta needs to know which side initiated each trade. Exchange data usually carries that. Where it does not, platforms estimate it, for example by comparing the trade price with the last bid and ask, and estimates can be wrong.
• It ignores passive intent. A large buyer working limit orders at the bid shows up as the passive side, not as buying. Delta sees aggression, not all interest.
• Fragmented markets. Spot forex has no central exchange and crypto trades on many venues, so delta from one source is a partial view.
• Resets change the picture. A session reset makes early-session CVD noisy. Compare like with like.

Delta works best combined with levels. On its own, a divergence in the middle of a range tells you very little; at a well-watched level with a volume profile edge behind it, it tells you much more.

The order flow workspace in Mizora Pro includes delta alongside the footprint, imbalances, a liquidity heatmap, a DOM ladder, time and sales, and signals for absorption and large prints.

It is in Beta and modelled from live prices, not exchange depth or tick data. That means the delta shown is a model of buying and selling pressure built from the live price stream, not a count of real exchange trades classified by aggressor. Use it to frame pressure around a level, and check it against price and structure on the chart.

You can study it on a free $50K practice account, and replay past sessions bar by bar in bar replay. Mizora Pro accounts trade simulated capital.