Prepare the structure
Paste CSV/TSV or import an Excel workbook, choose its sheet and inspect the grid. Map categories and series, then check the shape required by the selected chart family.
Heatmap Chart Maker
Paste a grid of values and get an exact heat map — every cell shaded to the number you entered, never to an approximation.
A heatmap, also written heat map, is a grid where colour encodes magnitude: rows and columns give you the two dimensions, and the shade of each cell gives you the value. It is the right chart when you have a measure across two categories — sales by region and month, errors by service and day, scores by team and criterion — and a bar chart would need dozens of bars to say the same thing. Note that a data heatmap is a different thing from a website heatmap: this page is about charting values you supply, not about tracking where visitors click.
Prism · real output
See the supplied values in the finished visual.
Inspect an actual output, then use the appropriate maker for your own data shape. Structured charts, diagrams and composed artwork offer different editing tools and export options.
Heatmap — fictional example
A current Prism render from explicitly supplied fictional inputs. Inspect the full-size output, original request and rendered HTML together.
Inspect the source brief or data
Team,Apr,May,Jun North,10,18,22 East,22,12,16 West,15,25,20
Read the sample review notes
Fictional demonstration data, not customer results. Check labels, units, branches and all supplied values before reuse.
Refine with meaning
Choose legible type, deliberate colors, labels and units. Bold is the default for new visuals; a saved or explicitly selected theme remains yours. Check figures against your source and inspect retained data after a chart-type change.
Inspect and share
Read the chart data table or diagram labels, add appropriate alternative text and inspect the actual export. Review and publication permissions are separate from clean-output download rights.
Data mapping, chart objects and accessibility
Inspect an imported workbook's sheet and cells, edit the data grid and choose series and category mappings. Chart-specific shape checks, axes, numeric formatting, labels and legends affect the reading. Review alternative text, long descriptions and the data table. A changed chart type can retain data that needs reshaping.
Graphs, compositions and connected data
Review nodes and branches, Mermaid interchange and saved revision comparisons for structured diagrams. Compositions can combine visual blocks with brand type and colors. Their editing tools differ from those used for structured charts. Connected data controls offer bounded filtering, sorting, column selection, row limits and supported calculated columns; inspect a refresh before accepting changed source values.
Campaign assets and print proofs
Campaign kits support channel choices, sized artwork, photos and crops, captions, selected-channel regeneration and review of edited copy. Print controls cover copy, layout, photo placement, fit, density and proof checks. Print supports English, Germanic, Latin, Cyrillic, Arabic, Indian, Chinese, Korean and Japanese language/script groups. Inspect the actual export and destination requirements.
Color and preflight options are checks with defined scope, not accessibility certification. Structured SVG editability does not imply that composed raster artwork has the same editing model.
What makes a heatmap chart maker trustworthy?
Values, not impressions
The shade of a cell is computed from the number you entered. Nothing is smoothed, rounded to a nicer band, or adjusted to make the grid look tidier.
The number is in the cell
A heat map a reader has to decode against a colour ramp is half a chart. Prism prints the value inside every cell, so nobody has to convert a shade back into a number.
No AI image model
The heatmap is rendered deterministically to SVG from your grid, not generated as a picture of a heatmap. That is why the numbers survive.
Heat map or bar chart: when to use which
Use a bar chart when you have one dimension and want precise comparison — the eye reads length far more accurately than colour. Use a heat map when you have two dimensions and want the pattern: which row runs hot, which column is empty, where the outlier sits. If your reader needs to quote exact figures, keep the values printed in the cells rather than relying on shade alone.
How do you make a heatmap with Gixo Prism?
1
Bring a grid
Paste rows and columns with a value at each intersection, or upload the CSV you already have.
2
Choose the scale
Pick the colour range and whether it runs from zero or from the minimum value. This changes what the chart says, so it is a decision rather than a default.
3
Review and export
Read the grid back against your source, then export as SVG for a deck, a doc or a page.
A heat map is one of 22 chart types Prism renders. See the full set on the chart maker overview.
Frequently Asked Questions
What is a heatmap chart?
A grid where colour encodes magnitude across two dimensions. Rows and columns give the categories; the shade of each cell gives the value. It is the standard way to show one measure across two category axes without drawing dozens of bars.
Is a heat map the same as a heatmap?
Yes — the one-word and two-word spellings refer to the same chart. Both are in common use, and this maker handles either phrasing.
Is this a website heatmap tool?
No. This is a data heatmap: you supply a grid of values and it renders them. Website heatmaps that show where visitors click or scroll are a different category of tool entirely.
Are the cell values exact or estimated?
Exact. Prism renders your grid deterministically to SVG, so the value you enter is the value the shade encodes. There is no AI image model between your data and the chart.
Can I print the numbers inside the cells?
Yes, and it is usually worth doing when a reader may need to quote a figure. Colour communicates the pattern; the printed value communicates the number.
What formats can I export?
Individual deterministic makers export HTML, SVG, PNG, PDF and PPTX. Compatible charts can contain native editable PowerPoint data; other supported maker visuals use selectable shapes and text. In the PPTX, bar, horizontal bar, stacked bar, line, area, pie, donut, scatter, radar, and bar-and-line combo charts arrive as native PowerPoint charts with their numbers in an embedded workbook that Edit Data opens; waterfall, funnel, Gantt, heatmap, treemap, symbol map, Marimekko, bubble, Sankey, bullet, slope, and dumbbell charts arrive as editable PowerPoint shapes and text, as does any chart PowerPoint cannot draw the way Prism does, such as a pie with a negative slice or an area chart with a missing value. Generated AI infographics, frameworks and decisions use their separate PNG/HTML path. Attributed HTML/SVG maker output is free; owners can download saved maker revisions without a current generation plan.
How much does Gixo Prism cost?
There's a 14-day free trial with no credit card. From there, Gixo Prism starts at $10/month for Starter (one seat) and rises through Professional, Business and Enterprise; the Brand Kit, which applies your own colours and typeface, starts on the Professional plan.
Explore the Prism chart toolkit
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