Up to four models

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Side by side on the same independent tests, with price and context. The link in your address bar shares this exact comparison.

Claude Opus 5.5GPT-5.6 Terra

Next to Claude Opus 5.5

Presets

Claude Opus 5.5

200188–211

WeightsClosed

ReleasedSep 2026

Price in / out$4.0 / $20

Context1M

Core tests taken4 of 8

GPT-5.6 Terra

178167–189

WeightsClosed

ReleasedJul 2026

Price in / out$2.0 / $12

Context1.05M

Core tests taken4 of 8

Claude Opus 5.5 leads GPT-5.6 Terra by 22 points, ahead on 3 of 4 shared core tests, at 1.8× the price.

Test by testindependent results · Epoch AI

Claude Opus 5.5GPT-5.6 Terra

Only tests that at least two of these models have taken. Bold rows are the core tests shown on every profile; all of these results inform the index score. Task length (METR) is listed below the chart because it is a duration, not a percentage.