The footprint chart and delta

A footprint chart (also called a cluster chart, or order flow bars) takes every print from the tape and sorts it into a grid: one column per bar, one row per price, and in each cell the volume that traded at the bid and the volume that traded at the ask. It is the tape, folded into a shape your eye can scan across an entire session.

Reading one footprint bar

Here is a single five-minute bar. The convention used in this course is bid volume × ask volume in each cell: sellers hitting the bid on the left, buyers lifting the ask on the right.

  Price   |  Bid vol x Ask vol  |
  --------+---------------------+
  5003.00 |     12 x    0       |  <- high; 12 sold, nobody bought
  5002.75 |     85 x   40       |
  5002.50 |    140 x  210       |
  5002.25 |    160 x  380       |
  5002.00 |    210 x  420       |  <- most volume: bar POC
  5001.75 |    190 x  260       |
  5001.50 |     95 x  110       |
  5001.25 |     30 x   60       |
  5001.00 |      0 x   18       |  <- low; 18 bought, nobody sold
  --------+---------------------+
  Total   |    922 x 1498       |  Delta = 1498 - 922 = +576

Read the bar from the bottom up as the sequence of the auction: buyers lifted from 5001.00 upward, the heaviest two-sided trade was at 5002.00, and at the top, 5003.00, twelve contracts sold and nobody bought. The bar closed somewhere in the middle.

The row with the most total volume (here 5002.00 with 630 contracts) is the bar's point of control. The bottom line is the bar's delta: total ask volume minus total bid volume. Positive means buyers were more aggressive across the bar; negative means sellers were.

Delta is not direction

The most common misreading of a footprint is treating positive delta as bullish. Delta measures who was aggressive. Price measures who won. Those can disagree, and when they do it is the most informative thing on the chart.

Bars 2, 3 and 5 are where the footprint earns its place. On a candle chart they look like an ordinary small-bodied bar. On a footprint they show a fight and who was losing it.

Key idea: Delta = ask volume − bid volume = who was aggressive. Price = who won. When aggression and result disagree, someone is absorbing, and that is worth knowing.

Where in the bar the volume sits

The vertical distribution matters as much as the total.

  Bar A (volume at top)       Bar B (volume at bottom)
  5003.00 |  40 x 310         5003.00 |   4 x   2
  5002.75 |  60 x 280         5002.75 |  10 x   8
  5002.50 |  30 x 120         5002.50 |  20 x  15
  5002.25 |  20 x  60         5002.25 |  60 x  70
  5002.00 |  10 x  25         5002.00 | 210 x 340
  5001.75 |   5 x  10         5001.75 | 180 x 290
  Delta       +640                        +245

Bar A: heavy buying at the top of the bar. If the bar closed near its high, buyers were in control and the auction is still searching upward. If it closed near its low, all that buying at the top was absorbed and those buyers are trapped.

Bar B: heavy buying at the bottom of the bar, light at the top. Buyers stepped in low and pushed up, but nobody was lifting at the high. The push is running out of aggression; lesson 3 calls the thin top a completed auction.

Same sign of delta, opposite meaning. Always look at where in the bar the volume is, and where the bar closed relative to it.

Bar POC and its shift

Tracking the bar POC from bar to bar shows where two-sided trade is migrating.

Bars 1 to 3: POC rising with price, delta positive, closes near highs. Healthy. Bar 4: POC still high but delta flipped negative and close fell back from the high. Bar 5: POC stayed at 5003.50 while price fell away from it and delta went strongly negative. The acceptance moved up and then the market rejected the higher prices. This is the footprint version of a failed push.

Choosing the bar type

Footprints work with time bars, but many order flow traders prefer bars that close on volume (every N contracts), on range (every N ticks of movement) or on delta. The reason: time bars in a quiet period contain little and in a fast period contain too much. Volume bars normalise for activity so that each bar represents a similar amount of business. There is no right answer; pick one, keep it fixed for weeks, and learn what normal looks like on it.

Try it: Take any ten consecutive footprint bars. For each, write down delta and price change (close minus open, in ticks). Mark every bar where the signs disagree, or where delta is large and the price change is small. Then look at what price did over the next three bars after each marked one. Do this for a few sessions and you will have your own evidence about what those disagreements mean on your product.

Recap

• A footprint bar shows bid volume and ask volume at every price within the bar; it is the tape, sorted.
• Delta = ask volume − bid volume = net aggression for the bar.
• Delta measures who was aggressive; price measures who won; disagreements indicate absorption or pulled liquidity.
• Where volume sits within the bar, and where the bar closes relative to it, changes the meaning entirely.
• Track the bar POC from bar to bar to see where acceptance is migrating.