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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 Sonnet 5.5Muse Spark 1.3

Next to Claude Sonnet 5.5

Presets

Claude Sonnet 5.5

193182–204

WeightsClosed

ReleasedSep 2026

Price in / out$2.0 / $10

Context1M

Core tests taken3 of 8

Muse Spark 1.3

170159–182

WeightsClosed

ReleasedSep 2026

Price in / out$1.25 / $4.25

Context1.05M

Core tests taken2 of 8

Claude Sonnet 5.5 leads Muse Spark 1.3 by 23 points, ahead on 2 of 2 shared core tests, at 2.0× the price.

Test by testindependent results · Epoch AI

Claude Sonnet 5.5Muse Spark 1.3

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.