What format do dates need to be in?

ISO `YYYY-MM-DD` at the start of the line. Anything after the date is treated as a count (must be numeric). Lines starting with `#` are comments and skipped.

How are intensity levels assigned?

Five bins relative to the year's peak — empty, <25%, <50%, <75%, ≥75%. So a day at 50% of your busiest day uses the middle shade. The bins re-balance whenever the data changes.

Calendar Heatmap from Date List

Turns a column of dates into the GitHub-contribution-graph view of a year. Each line can be just a date (`2026-03-15`) for count 1, or a date with a number (`2026-03-15 4`) when you have weights. The grid auto-bins counts into five intensity levels relative to the year's peak, picks a palette, and surfaces the longest streak and current streak below. Useful for habit trackers, commit history copies, sales/error logs — any time-series where the rhythm matters more than the exact value.

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How to use

Paste your dates, one per line. Optional second column is the count (default 1) — duplicates on the same date are summed.
Set the year and choose a palette + week start. Hover any cell to see its date and count.
Read the streak metrics below: total active days, average per active day, longest and current streaks.

Frequently asked questions

What format do dates need to be in?: ISO `YYYY-MM-DD` at the start of the line. Anything after the date is treated as a count (must be numeric). Lines starting with `#` are comments and skipped.
How are intensity levels assigned?: Five bins relative to the year's peak — empty, <25%, <50%, <75%, ≥75%. So a day at 50% of your busiest day uses the middle shade. The bins re-balance whenever the data changes.

Related tools

Lunar Calendar Converter

Convert between solar (Gregorian) and East Asian lunisolar calendar dates. Returns zodiac animal and ganzhi (heavenly-stem/earthly-branch) year name. Covers 1900-2099.

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