Which is better, Claude Sonnet 5.5 or GPT-5.3 Codex?

Claude Sonnet 5.5 scores higher on 2 of 2 shared quality measures, GPT-5.3 Codex on 0. Claude Sonnet 5.5 costs about 17% less than GPT-5.3 Codex on a blended price of $4.00 against $4.81 per million tokens. Which one is better for you depends on your task and budget, so test both on your own work.

Which is cheaper, Claude Sonnet 5.5 or GPT-5.3 Codex?

Claude Sonnet 5.5 is cheaper on blended price: $4.00 per million tokens for Claude Sonnet 5.5 against $4.81 for GPT-5.3 Codex. For 100 chats of about 1,000 tokens in and 500 tokens back, that is about $0.70 for Claude Sonnet 5.5 and $0.88 for GPT-5.3 Codex.

Which can read longer documents, Claude Sonnet 5.5 or GPT-5.3 Codex?

Claude Sonnet 5.5 has a context window of 1M tokens and GPT-5.3 Codex has 272K tokens.

AI Rankings

Claude Sonnet 5.5 vs GPT-5.3 Codex: Scores, Price and Which to Choose

Side by side on every measure both models share: overall score, human votes, tests, price and context window. Close results are called too close to call.

Data updated 26 Oct 2026

Read the model pages for the full picture: Claude Sonnet 5.5 and GPT-5.3 Codex.

Side by side

A check mark shows the better side on each measure. Scores that are too close to call have no winner.

Claude Sonnet 5.5 compared with GPT-5.3 CodexClaude Sonnet 5.5 against GPT-5.3 Codex on 4 measures. Claude Sonnet 5.5 is better on 4, GPT-5.3 Codex on 0, 0 are too close to call, 0 have no data for one side.

Claude Sonnet 5.5
GPT-5.3 Codex

Epoch Capabilities IndexClaude Sonnet 5.5 leads
Combined score over many tests. Bar shows where it sits between the lowest and highest score we track.
Claude Sonnet 5.5:
Better: 166.2
GPT-5.3 Codex:
157.1
Arena web development ratingClaude Sonnet 5.5 leads
Rating from head-to-head votes by people. Bar shows where it sits between the lowest and highest score we track.
Claude Sonnet 5.5:
Better: 1769
GPT-5.3 Codex:
1407
Blended price per million tokensClaude Sonnet 5.5 costs less
Blended price: lower is better.
Claude Sonnet 5.5:
Better: $4.00
GPT-5.3 Codex:
$4.81
Context windowClaude Sonnet 5.5 leads
How much text it can read at once.
Claude Sonnet 5.5:
Better: 1M tokens
GPT-5.3 Codex:
272K tokens

Data updated 26 Oct 2026. Only measures that both models have are shown.

The numbers

Claude Sonnet 5.5 against GPT-5.3 Codex, measure by measure. A check mark shows the better side.
Measure	Claude Sonnet 5.5	GPT-5.3 Codex
Epoch Capabilities Index	166.2	157.1
Arena web development rating	1769	1407
Blended price per million tokens	$4.00	$4.81
Context window	1M tokens	272K tokens

What it costs in everyday terms

Estimate for 100 chats of about 1,000 tokens in and 500 tokens back, from list prices. Your bill depends on how you use it.

100 chats with Claude Sonnet 5.5: $0.70; Blended price $4.00 per million tokens.
100 chats with GPT-5.3 Codex: $0.88; Blended price $4.81 per million tokens.

Who should pick which

Pick Claude Sonnet 5.5 if these matter most

Epoch Capabilities Index: 166.2 against 157.1
Arena web development rating: 1769 against 1407
Blended price per million tokens: $4.00 against $4.81
Context window: 1M tokens against 272K tokens

Pick GPT-5.3 Codex if these matter most

It does not lead clearly on any measure we hold for both models.

Scores come from tests and votes, not from your own work. Try both on a task you care about before you commit.

Go deeper

Claude Sonnet 5.5: full page

GPT-5.3 Codex: full page

Questions about this comparison

Which is better, Claude Sonnet 5.5 or GPT-5.3 Codex?: Claude Sonnet 5.5 scores higher on 2 of 2 shared quality measures, GPT-5.3 Codex on 0. Claude Sonnet 5.5 costs about 17% less than GPT-5.3 Codex on a blended price of $4.00 against $4.81 per million tokens. Which one is better for you depends on your task and budget, so test both on your own work.
Which is cheaper, Claude Sonnet 5.5 or GPT-5.3 Codex?: Claude Sonnet 5.5 is cheaper on blended price: $4.00 per million tokens for Claude Sonnet 5.5 against $4.81 for GPT-5.3 Codex. For 100 chats of about 1,000 tokens in and 500 tokens back, that is about $0.70 for Claude Sonnet 5.5 and $0.88 for GPT-5.3 Codex.
Which can read longer documents, Claude Sonnet 5.5 or GPT-5.3 Codex?: Claude Sonnet 5.5 has a context window of 1M tokens and GPT-5.3 Codex has 272K tokens.

Where this data comes from

Epoch AI: Benchmark data: Epoch AI, 'Capabilities & benchmarking', epoch.ai/benchmarks (CC BY 4.0). We match models across sources, rank them and show them in charts. Scores are not changed. Epoch AI does not endorse this site.
Arena (formerly LMArena): Human-preference ratings: Arena (arena.ai) leaderboard dataset, CC BY 4.0. We keep the latest published ratings, match them to models from other sources and rank them. Ratings are not changed. Arena does not endorse this site.
LiteLLM model price list: Prices and context windows: LiteLLM model price list (github.com/BerriAI/litellm, MIT licence). We use the model maker's own price entry when there is one. Prices change often, so always confirm on the maker's site before you buy.

Newest data on this page: 26 Oct 2026. Prices are list prices and change often, so confirm on the maker's site before you buy. Sponsors never change a score or an order. How we calculate this · Report a mistake