Level 5 · Fix the chart before it ships

Power BI’s defaults are built to show you the data quickly, not to present it. Before a chart goes on a big screen, it needs a short review against a handful of rules.

What you are working in

The charts are drawn on this site from the store’s 2025 data; Power BI Desktop runs only on Windows. The fixes are all in the Format visual pane (the paintbrush in Visualizations): Y-axis → Range → Minimum for the baseline, Columns → Colors for colour, General → Title for the title, and the More options (…) → Sort axis menu on the visual for sorting.

Rule 1: bars and columns start at zero

People compare bars by their length. With the axis at $200K, Textiles’ column shows only its $51K above the cut, and Furniture’s shows $373K, so Furniture is drawn about seven times taller. Its real sales are about 2.3 times Textiles’. Power BI chooses the axis range automatically and sometimes starts above zero; set the minimum to 0 for any bar or column chart. Line charts may zoom in, because they are read by slope, not length, as long as the axis is labelled.

Rule 2: order carries meaning

Alphabetical order is right for finding a name in a long table and wrong for a chart about which category sold most. Sort by the value, largest first, unless the categories have a natural order (months, sizes, age bands).

Rule 3: a limited palette

Colour should mean something. When each column already has a label under it, giving each one a colour adds a legend to decode and nothing to learn. Use one colour, and an accent colour for the one bar the story is about. Keep contrast high enough to read on a projector.

Rule 4: titles that say something

“Sum of line_total by category” is how Power BI names a visual it built from fields. Rename it, in the visual’s Title text, to what the reader should take away: “Furniture and Outdoor led 2025 sales”, or at least “Sales by category, 2025”. The same goes for axis titles and measure names: “Sales”, not “Sum of line_total”.

Page layout and consistency

The same rules scale up to a page: cards and KPIs along the top, the main charts in the middle, detail tables at the bottom, with space between visuals. Use the same colour for the same thing on every page (Sales is always the same blue), the same number formats, and aligned edges (Format → Align on the ribbon).

Common mistakes

• Trusting the automatic axis. Check every bar chart’s minimum.
• Rainbow defaults. Colour by category only when the categories need to be told apart.
• Shipping the field names. Every visible label is a word your reader has to understand.