Jaccard Similarity Calculator

Summary

The Jaccard similarity index measures how similar two sets are by dividing the size of their intersection by the size of their union. It returns a value between 0 (no overlap) and 1 (identical sets). This tool accepts any comma- or space-separated tokens — words, tags, IDs, or other discrete items — and displays the intersection, union, unique-only items, and the final similarity score.

How it works

1. Paste or type tokens into Set A and Set B — separate them with commas or spaces.
2. The calculator splits each input into unique tokens, ignoring duplicates and case.
3. It computes the intersection (tokens in both sets) and the union (all unique tokens combined).
4. The Jaccard index is calculated as |A ∩ B| / |A ∪ B|.
5. Results update live as you type, showing the score, intersection, and union lists.

Use cases

• Measure document or keyword overlap for plagiarism detection.
• Compare product tag lists to find similar items in a catalog.
• Evaluate recommendation system quality by checking predicted vs. actual item sets.
• Assess gene set similarity in bioinformatics research.
• Deduplicate datasets by identifying near-duplicate records.
• Validate NLP tokenizer output by comparing expected vs. actual token sets.

Frequently Asked Questions