Tableau Course
Heat Maps
A heat map places two Dimensions on a grid and fills each cell with a colour encoding a Measure. The result is a compact matrix that lets the eye scan across rows and columns simultaneously to spot the hotspots and cold spots in your data.
Heat Maps — Two Dimensions, One Measure
A heat map is built on a crosstab structure — rows represent one Dimension, columns represent another, and each cell at the intersection is coloured by a Measure value. Unlike a table of numbers, the colour encoding lets the reader absorb an entire matrix in a single glance. Cells that stand out from the surrounding colour immediately draw attention — no scanning of numbers required.
In Superstore, a heat map of Sub-Category (rows) by Region (columns) coloured by Profit Ratio immediately reveals which combinations are profitable and which are not — across all 17 sub-categories and all 4 regions in a single compact view.
Building a Heat Map — Step by Step
Heat Map — Labelled Mockup
Encoding Size as a Second Measure
A heat map can encode a second Measure by varying the size of the square marks in addition to their colour. This is done by dragging a Measure to the Size channel on the Marks card. The result is sometimes called a proportional heat map — cells that represent high Sales are physically larger, cells that represent low Sales are smaller, and the colour still encodes Profit. This adds a third dimension of information without adding another chart.
Use this technique carefully — when squares vary greatly in size, the grid alignment that makes a heat map readable begins to break down. Reserve the Size channel for situations where the second Measure genuinely changes the story rather than adding visual noise.
Sorting Rows and Columns for Maximum Insight
The default row and column order in a heat map is alphabetical — which rarely puts the most important patterns at the top. Sorting rows by a Measure reveals the overall best and worst performers immediately. Right-click the row header pill on the Rows shelf → Sort → Field → choose Profit → Descending. The most profitable Sub-Categories rise to the top, the loss-makers sink to the bottom. The heat map now reads as a ranked performance matrix — the orange cluster at the bottom is instantly visible as the problem area.
Heat Map vs Highlight Table
Heat maps are the most underused chart type in business dashboards for the amount of insight they pack into a small space. A 17-row by 4-column heat map of Sub-Category × Region profit delivers the same information as 68 individual bar chart comparisons — but it fits in a space smaller than a single bar chart and is readable in under five seconds. The key to a great heat map is the colour palette choice. Always use a diverging palette when your Measure can be positive or negative — orange-blue or red-green centred at zero. A sequential palette (light to dark blue) is correct when all values are positive and you are simply showing intensity. Never use a rainbow palette — it introduces false patterns that do not exist in the data. Sort your rows by total Profit descending before publishing to any audience, and always include exact values in the labels so the chart works for readers who need precision as well as pattern.
Practice Questions
1. You have a text table of Sub-Category by Region. What mark type do you switch to on the Marks card to convert it into a heat map?
2. Profit is on the Color channel of a heat map and ranges from negative to positive. Which colour palette type is most appropriate?
3. A heat map rows are in alphabetical order. You want to sort Sub-Categories so the most profitable appear at the top. How do you do this?
Quiz
1. After setting the mark type to Square on a Sub-Category × Region grid, what is the next step to make the cells show profit performance through colour?
2. Sales is dragged to the Size channel of a heat map that already has Profit on the Color channel. What does this addition communicate?
3. A manager wants to spot which combinations of 20 product lines and 4 sales regions have negative profit — at a single glance. Which chart type handles this most efficiently?
Next up — Lesson 26: Highlight tables — combining exact numbers with colour shading to create a performance matrix that serves both analytical and presentation needs.