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The Variance Bridge: Showing Why the Total Moved, Not Just That It Did

Michael Nocito · Updated August 2026 · Every number on this page was worked before it was published

A variance total answers one question and provokes a second. Yes, we are 28,750 ahead of plan. Because of what? A bridge chart is the answer laid out as bars, starting at the plan, stepping through one bar per reason, and landing on the actual.

What you do: decide the bars before you open the chart menu, make them sum exactly to the gap, and give any leftover its own honest bar. The chart type takes two minutes; the decomposition is the job.

The short version. A bridge that does not add up is not a chart, it is an illustration.

The bridge this page builds

The four middle bars are 9,200 + 9,350 + 4,200 + 6,000 = 28,750, which is exactly 428,750 minus 400,000. That is the whole test of a bridge, and it is worth doing in a cell with a formula rather than by eye:

=SUM(middle_bars) - (end_total - start_total)

That cell should read 0. If it reads anything else, do not adjust the bars until it does. Add the difference as a bar named "unexplained" and put it on the chart. Reviewers trust a bridge with a labelled residual far more than one that lands perfectly and cannot be reproduced.

Building it in Excel

Excel 2016 and later

1. Lay out two columns: label and value. Start and end hold the totals, the middle rows hold the changes, with negatives entered as negatives.
2. Select both columns, Insert, then the Waterfall chart in the chart gallery.
3. Click the first bar once to select the series, click again to select just that point, right click, Set as Total. Repeat on the last bar.
4. Turn on data labels. A bridge without labels is a stack of rectangles.

Older Excel, or when you need full control

Use a stacked column with three series: an invisible base, the increases, and the decreases. The base is what floats each bar off the axis.

Base      =IF(step is a total, 0, previous running total + MIN(value,0))
Increase  =MAX(value,0)
Decrease  =-MIN(value,0)

Stack them base, increase, decrease, then set the base series fill to No fill and remove it from the legend. The connector lines that the native chart draws for you can be added as a second plot or left off; they help a reader follow a long bridge and clutter a short one.

Choosing the bars

The bars are the argument. Three rules, in order of how often they are broken.

Group by kind, then order within the group. Volume effects together, rate effects together, one-offs last. A bridge sorted purely by size looks like a league table and quietly implies that the biggest bar is the most actionable, which is often the opposite of true: the one-off is usually the biggest and the least repeatable.

Between four and seven middle bars. Below four you have not explained anything the total did not already say. Above seven the reader stops reading labels and starts looking at shapes. If you have eleven reasons, the eleventh is not a reason, it is a level of detail.

Name the bar after the cause, not the account. "Volume, existing regions" is a cause. "GL 4010 movement" is a place where the money was recorded. Only one of those tells somebody what to do differently.

When a bridge is the wrong chart

A bridge is specifically a from one number to another number chart. Using one to show a composition at a point in time is the most common misuse, and it produces a chart whose bars cannot sum to anything meaningful.

How to apply this to your own work

1. Take your last variance total and write down, in words, the four reasons it moved. If you cannot get to four, the bridge is premature and the analysis is not done.
2. Put a number against each reason, then compute the residual. Whatever is left over is a real bar with a real name.
3. Build the two columns first and the chart last. The layout is where mistakes are visible; the chart is where they are hidden.
4. Add the check cell that must read zero, and leave it in the workbook rather than deleting it before you send.
5. Read the bridge aloud left to right as one sentence. If the sentence needs an and also more than twice, you have too many bars.

The one habit to keep

Build the bridge before the meeting, not for the meeting. If the bars do not sum, you have found something real in the data, and you have found it while there is still time to look into it rather than while somebody is asking about it.

Could you name the four largest reasons your last total missed, without opening the file?