---
title: "Pairwise Comparison Ranking Tool | Bright Peaklet"
description: "Rank a list by comparing items two at a time. Every pair once, keyboard shortcuts and undo, then a ranked list with win counts. Saved in your browser."
url: https://brightpeaklet.top/pairwise-ranking/
---

# Pairwise ranking: two at a time

Ranking a long list in one go is hard. Choosing between two is easy. Answer one quick question per pair and the ranking builds itself.

## How pairwise ranking works

Every item meets every other item exactly once. With n items that is n(n − 1) ÷ 2 pairs: 5 items take 10 choices, 10 items take 45 and 20 items 190. The pairs come in round-robin order, so the same item rarely appears twice in a row and you judge each pair fresh.

A win scores 1 point and "about the same" gives each item half a point. Items are ranked by points, the scoring used in round-robin tournaments and in Copeland's voting method. When two items finish level, the one that won their head-to-head goes first.

Sometimes the answers go round in a circle: A over B, B over C, yet C over A. That isn't a mistake on your part; it usually means those items are close, or that you were weighing them on different grounds. The tool counts these circles so you can look again at those items.

## Sources

- Thurstone LL. A law of comparative judgment. *Psychological Review* 34 (1927), 273–286: the method of paired comparisons. Overview: [Pairwise comparison](https://en.wikipedia.org/wiki/Pairwise_comparison_(psychology)).
- [Copeland's method](https://en.wikipedia.org/wiki/Copeland%27s_method): ranking by pairwise wins, with half points for ties.

## Questions

**How many items can I rank?**

Up to 20, which takes 190 comparisons. For longer lists, shortlist first, or use the decision matrix to score items against criteria.

**Can I change an answer?**

Undo steps back one answer at a time and asks that pair again. Reset answers starts over with the same list.

**Why do items share a rank?**

They won the same number of points and their head-to-head was a tie or part of a circle, so nothing separates them.