Waterfall Chart Builder
Takes a Category and Amount table and renders a bridge: a starting total, a series of increases and decreases floating between them, and an ending total. It is the standard way to explain how a figure moved from one value to another, which a pair of bars cannot do.
How to use it
- Paste two columns: Category and Amount, with negatives for decreases.
- Make the first and last rows your opening and closing totals.
- Order the intermediate steps deliberately — the sequence is part of the message.
- Choose a theme and export a high-resolution PNG.
Absolute totals and floating steps
The chart treats the first and last rows differently from everything between them. Those two are absolute: they are drawn from zero and represent the opening and closing values. Every row in between is incremental, drawn floating from wherever the running total sits.
A floating bar is what makes the format work. Its bottom edge is the running total before the step and its top edge is the running total after, so the bar length is the size of the change and its vertical position is the level it happened at. A cost of 200 taken at a running total of 1,000 sits in a different place from the same cost taken at 400, and that placement is information a plain bar chart discards.
Positive amounts step up and negative amounts step down, with colour reinforcing the direction. The closing total should equal the opening total plus the sum of the steps, and if it does not, something is missing from the bridge — which is one of the more useful properties of the format, since the reconciliation is visible rather than assumed.
What it is used for
The dominant use is a variance bridge: explaining the difference between two figures in terms of the components that caused it.
Budget to actual is the canonical case. Budgeted revenue as the opening bar, then the individual variances — volume, price, mix, foreign exchange — as steps, then actual revenue as the closing bar. The reader sees not just that there was a shortfall but which components caused it and in what proportion.
Period over period works the same way: last quarter revenue, then new customers, expansion, contraction, and churn, then this quarter revenue. This is the standard SaaS revenue bridge and it is far more informative than two bars, because the net change is usually small relative to the gross movements underneath it. A flat quarter can conceal substantial new business offset by substantial churn, and the waterfall is what makes that visible.
Profit bridges follow the same shape: revenue at the top, then cost of goods, operating expenses, and tax as negative steps, arriving at net income. Here the intermediate subtotals — gross profit, operating profit — often matter enough to warrant their own absolute bars.
Ordering is an editorial decision
The steps sum to the same closing total in any order, so the sequence is a choice, and it changes what the chart emphasises.
Grouping all the increases first and then all the decreases produces a clean peak-and-descent shape that is easy to read, and it separates the drivers from the drags. Ordering by magnitude puts the biggest movers first, which is right when the message is what dominated. Ordering by process — the sequence in which things actually happened — is right when the narrative matters more than the size.
What to avoid is an order that appears meaningful but is not, such as alphabetical or spreadsheet row order. Readers assume the sequence means something, and if it does not, they will infer a relationship that is not there.
The other decision is granularity. Too few steps and the chart says little more than a pair of bars; too many and the small ones become unreadable slivers. Somewhere between five and ten steps is usually right, with the immaterial ones combined into a single Other bar rather than shown individually.
Where it breaks down
A waterfall assumes the components are additive and independent. Where they interact, the decomposition is not unique and the chart implies more precision than exists.
Price and volume variances are the standard example. If both price and volume changed, part of the total variance is attributable to their interaction, and how you allocate that part is a convention rather than a fact. Different allocation methods give different step sizes for the same underlying result, so a variance bridge should state its convention rather than presenting one decomposition as the decomposition.
Large intermediate swings against a small net change also cause trouble. If the running total goes far above or below both endpoints, the axis has to accommodate the excursion, and the opening and closing bars get compressed into near-identical heights. The chart is accurate and the endpoints, usually the headline, become hard to read.
Finally, a total that crosses zero — from profit to loss — makes the running total ambiguous to follow, since the bars cross the axis mid-sequence. Splitting into two charts, or annotating the crossing explicitly, reads better than leaving the reader to work it out.
At a glance
| Input format | Two columns: Category and Amount |
|---|---|
| First and last rows | Absolute totals, drawn from zero |
| Middle rows | Incremental, floating from the running total |
| Negative amounts | Step down, coloured as decreases |
| Recommended steps | Five to ten between the totals |
Frequently asked questions
How do I mark the opening and closing totals?
The first and last rows are treated as absolute totals drawn from zero. Everything between them is incremental.
How do negatives work?
Negative amounts step the running total down and are coloured as decreases. Positive amounts step up.
What order should the steps be in?
A deliberate one. Increases then decreases reads cleanly; by magnitude emphasises the biggest movers; by process suits a narrative. Avoid alphabetical.
Why does my closing total not match?
The opening total plus the steps must equal the closing total. A mismatch means a component is missing from the bridge.
When is a waterfall the wrong format?
When the components interact rather than being additive, or when large intermediate swings compress the endpoint bars into near-identical heights.
Read more
Flow and change — Two bars tell you a number changed. These formats tell you what changed it, which is usually the question.