Venn Diagram Maker

About the Venn Diagram Maker

Draw Venn diagrams for 2, 3 or 4 sets in two ways. Paste lists — names, email addresses, product codes, one per line — and the tool finds every intersection: which items are in A only, in A and B only, in all sets, and so on, with the members of each region listed and ready to download. Or type the numbers you already have: the size of each set and of its overlaps.

For 2 or 3 sets the diagram can be area-proportional (circle areas follow your numbers — exactly for two sets, as closely as circles allow for three, with the remaining error reported) or classic (equal circles, every region shown). Four sets use four ellipses, the classic layout in which all 15 regions exist. Edit the set names and colours, then download PNG or SVG. The lists never leave your browser.

Common uses

• Comparing two or three lists: customers who bought both products, students in several clubs, overlapping mailing lists.
• Showing survey results such as “which of these apps do you use?”.
• Teaching sets, unions and intersections with real numbers.
• Finding the items that appear in every list, or in exactly one.

Totals or regions?

Numbers for overlaps can mean two things. As totals, “A and B” counts everyone in both A and B — including those also in C — the way most survey tables report it. As region counts, each number is one region on its own (“A and B only”, not C). With totals, the region counts come from inclusion–exclusion: for each region you add and subtract the totals of the overlaps that contain it, e.g. A only = |A| − |A∩B| − |A∩C| + |A∩B∩C|. If the numbers contradict each other (an overlap larger than a set, or a negative region), you get a message saying which numbers to check.

Area-proportional diagrams and their limits

In an area-proportional (Euler) diagram each circle’s area equals its set’s size. Two circles can always match both sizes and their overlap exactly: the distance between the centres is found so that the lens-shaped overlap has the right area. Three circles generally cannot match all seven regions — Wilkinson (“Exact and approximate area-proportional circular Venn and Euler diagrams”, IEEE TVCG 18(2)) shows why — so the circles are first placed with the venn.js layout algorithm and then moved to make the squared error over all seven regions as small as possible. The notes give how much of the drawn area ends up in the wrong region, and the table shows each region’s number next to its drawn share. Four circles cannot show all 15 regions of four sets, so four sets use the classic four-ellipse layout, which shows every region but does not size them by count.

How lists are matched

Each line (or comma-separated part) is one item; spaces at the ends are trimmed and empty lines ignored. With Ignore upper/lower case on, “Asha” and “asha” are the same item (the first spelling is kept). An item repeated inside one list counts once. The CSV download has one row per item with yes/no for every set and its region, so you can sort or filter it in a spreadsheet.

Limitations

• 2 to 4 sets; for five or more, an UpSet-style chart or a table works better than a Venn diagram.
• Up to 50,000 items per list.
• Region labels that do not fit inside a small region are left out of the drawing (hover or tap it, or read the table).
• Items are matched exactly (apart from case and surrounding spaces): “Mumbai” and “Mumbai.” are different items.

Privacy

Everything happens in your browser. What you enter or open here is not uploaded or stored by MySmartCoPilot.