# Reading a money-flow diagram of your finances > How to read a Sankey diagram of income and spending, what the shape of it tells you, and the three things to look at first. Source: https://trybica.com/guides/money-flow-sankey/ Updated: 2026-08-13 --- A money-flow diagram — a Sankey — shows your month as a river. Income enters on the left as one or more streams, splits into categories, and exits on the right. The width of every band is proportional to the amount flowing through it. It contains the same information as a table of category totals. It's more useful anyway, because proportion is something people read instantly and numbers are something people have to compute. ## Reading it Three elements: **Sources, on the left.** Salary, freelance income, interest, refunds. Usually one dominant band and a few thin ones. **Flows, in the middle.** Each split is a division of the total. The thickness of the band going to *Housing* against the one going to *Groceries* is the comparison, and you don't have to do arithmetic to see it. **Destinations, on the right.** Where it ended up: spent by category, or saved. The one thing that should *not* appear anywhere is a transfer between your own accounts. Money moving from your current account to your savings is not a flow out of your finances, and a diagram that shows it as one is [misleading you](/guides/transfers-are-not-spending/). ## The three things to look at first ### 1. Is there a band going to savings at all? The band on the right representing money that didn't leave is the most important one in the diagram, and it's the one people don't look for. If it's missing, the month broke even or worse regardless of what anything else looks like. If it's a thin thread against a wide income band, that ratio *is* your savings rate, visible without calculating it. ### 2. Which single band is widest after housing? Housing is almost always the widest, and almost always the one you can't change this month. The second-widest is the interesting one, because it's usually large enough to matter and elastic enough to move. For most households it's food — often split across *Groceries* and *Eating out*, which is exactly why those two are worth [keeping separate](/guides/spending-categories-that-work/). Merged, food looks like one immovable necessity. Split, one half is a necessity and the other is the most flexible spending you have. ### 3. How wide is the band you can't name? The *Other* band is the diagram's honesty check. A thin one is normal and healthy. A wide one means a meaningful share of your money is going somewhere you haven't characterised — and you can't make a decision about a band with no name on it. ## Shapes worth recognising **Wide and even.** No dominant band, everything mid-sized. Usually means the categories are too coarse, or spending is genuinely diffuse — the second is hard to act on, the first is a five-minute fix. **One enormous band.** Housing over half the income. See [fixed vs variable spending](/guides/fixed-vs-variable-spending/): this is a structural situation, and no amount of trimming the small bands changes it. **Many thin threads.** Death by a thousand cuts, and often a subscriptions problem hiding in plain sight. [Worth auditing](/guides/find-forgotten-subscriptions/). **Income narrower than outflow.** The month spent more than it earned. Obvious in a diagram, easy to miss in a table, because a table doesn't force the two to be the same width. ## Comparing months A single month is a snapshot; two months side by side is where it becomes useful. Look for a band that changed width — that's a behaviour change, visible without tracking a number over time. Watch for the annual costs, though. The month your car insurance lands has a band that doesn't exist in any other month, and reading it as a trend is a mistake. [Three months](/guides/where-your-money-goes/) is the minimum before drawing conclusions about anything. ## Why the visual form earns its place There's a real difference between reading *"eating out: €340"* and seeing that the eating-out band is nearly as wide as the rent band. The first is a fact you file away. The second is a comparison you can't unsee. That's the entire argument for the diagram. It doesn't tell you anything a table couldn't. It just makes the proportion impossible to skip past — which for most people is the step that was actually missing. You can see one built from real anonymised data on the [Bica home page](/), and your own once your accounts are connected.