Free Heat Map Generator & Heatmap Maker
Charts & GraphsPaste a table and every cell is colored by its value: TV episode ratings, GitHub-style calendars, monthly returns and gradebooks. Free PNG, no signup.
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How to Use
- 1
Pick the kind of heatmap
Choose Grid, Episode ratings, Calendar or Monthly returns at the top of the Data panel. Each one opens with a ready-made example you can replace.
- 2
Paste your data
Paste a spreadsheet range with row and column labels, lines like "S1E1 8.4", date,value lines, or lines like "2024-01, 2.4". Blank cells stay empty instead of counting as zero.
- 3
Choose the colors
Pick a palette, then a smooth gradient or labeled bands. Reverse it, or set the range yourself (Auto, 1–10 or Custom).
- 4
Add the extras
Show averages for every row and column, ring the highest and lowest cells, transpose or sort, then click the title, subtitle, axis titles, legend title or source line on the chart to type your own.
- 5
Download
Pick a theme and a size (Slide, Page, Square, or Story 1080×1920 for Shorts, Reels and TikTok), then download a free PNG at exactly that size.
Why Choose GraphMake?
What Is a Heatmap?
A heatmap is a table in which color stands in for each number. Rows and columns keep their labels, but instead of reading every value you see the pattern at once: the hot corner, the cold week, the one bad episode in a great season.
Use one when your data has two dimensions and one measure: region and month for sales, season and episode for ratings, week and weekday for a calendar, year and month for returns. When there is only one dimension, a bar chart from the bar chart maker says it more plainly.
Episode Ratings Heatmaps
The episode ratings grid is one of the most shared charts online: seasons run across, episodes run down, and every cell is colored by its rating, so a show's peak and its slump are obvious from across the room.
Paste one line per episode, such as S1E1 8.4, or a grid copied from a spreadsheet. Bands mode colors the grid Bad, Regular, Good, Great and Awesome on a fixed 1–10 scale, so two shows can be compared fairly, and season averages add a summary row along the bottom.
Calendar Heatmaps
A calendar heatmap is the GitHub contribution graph applied to anything you count by day: kilometres run, pages written, sales, support tickets. Each day is a square, weeks run left to right, and a darker square means a bigger day.
Paste dates with values, or just dates to count occurrences. Rest days stay blank rather than showing as zero, and the legend shows the lowest and highest days at either end of the scale.
Choosing Heatmap Colors
Use a single-hue palette, light to dark, when the numbers only go up, such as sales or ratings. Use a diverging palette, red through neutral to green, when the numbers can be negative, such as returns or change from last year, so zero sits on the neutral middle.
Gradient mode shows every difference; Bands mode groups values into a few solid steps with round cut points, which are easier to read aloud (episode ratings get the named rating bands). Reverse the palette when low is good, such as error rates or response times, and set a custom range when several charts need to share one scale.
What You Can Create
TV Episode Ratings
The viral episode-by-episode grid for any show: seasons across, episodes down, rating bands, and season averages along the bottom.
Calendar Heatmaps
A GitHub-style year of runs, study sessions, sales or streaks, one square per day.
Monthly Returns
A portfolio or strategy by month and year, red for losses and green for gains, with compounded yearly totals.
Business Reports
Sales by region and month, or team KPIs by week, with row and column averages for the monthly deck.
Gradebooks
Students down, assignments across, blanks for missing work, so a struggling student or a hard test stands out.
Frequently Asked Questions
Is this heat map generator free?
Yes. Making a heatmap and downloading it as a PNG is free, with no signup and no watermark. The PNG is exactly the canvas size: Slide 1280×720, Page 816×1056, Square 1080×1080 or Story 1080×1920. GraphMake Pro adds a vector SVG and 2×, 3× and 4× HD PNGs.
How do I make a TV show episode ratings graph?
Choose Episode ratings and paste your ratings. It reads lines like S1E1 8.7, S01E01, 1x01 or "Season 1 Episode 1", ratings written as 8.7/10, a CSV with season, episode and rating columns (extra columns such as the title are ignored), or a grid either way round. Short seasons leave empty cells, and specials (season 0) are left out.
What do the rating colors mean?
In Bands mode, episode ratings use a fixed 1–10 scale: under 6 is Bad, 6–7 Regular, 7–8 Good, 8–9 Great and 9 or more Awesome, and a rating of exactly 7 counts as Good. The legend spells the bands out. Switch to Gradient for a smooth scale instead.
How does the calendar heatmap work?
It lays weeks across and weekdays down, like a GitHub contribution graph. Paste one date per line with an optional value: repeated dates add up, and a date with no number counts as 1. Weeks can start on Sunday or Monday, leap days land correctly, and it takes up to about three years. On tall canvases the year wraps into stacked strips so the squares stay big.
How is the yearly total calculated in a monthly returns heatmap?
By compounding the months, (1 + r₁)(1 + r₂)… − 1, the way returns actually add up: +10% followed by −10% is −1.0% for the year, not 0%. A year still in progress is marked as year to date. Values like 0.024 are read as 2.4%, with a note, and the colors are centered on 0% so gains and losses read at a glance.
What happens to blank or bad cells?
A blank cell, "-" or "n/a" is treated as missing, not zero: it is drawn hatched and left out of the averages and the color range. If a cell has a word where a number should be, the Data panel names the row, and the download waits until you fix it.
Can every number be read on every color?
Yes. Colors are mixed in OKLab so a gradient brightens evenly, and each number is set in black or white, whichever contrasts more with its cell — at least 4.5 : 1 on every palette color. All the values share one size, the largest at which every one fits its cell.
What if my table is too big for the canvas?
The canvas grows taller instead of cutting rows off. When cells get too small for their numbers, the numbers hide and the panel tells you why, and suggests Transpose when turning the table would make the cells bigger.
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