--- title: "Is Claude Sonnet 5.5 still undominated? · Undominated.ai" canonical: https://undominated.ai/check/anthropic__claude-sonnet-5.5/ description: "Claude Sonnet 5.5: whether it is still undominated. If anything in this catalogue is both better and cheaper, it is named, as of Oct 6, 2026. Unrated stays unrated." --- # Is Claude Sonnet 5.5 still undominated? · Undominated.ai > Claude Sonnet 5.5: whether it is still undominated. If anything in this catalogue is both better and cheaper, it is named, as of Oct 6, 2026. Unrated stays unrated. # Is Claude Sonnet 5.5 a good deal? Whether anything in this catalogue beats Claude Sonnet 5.5 on both quality and price, and what you give up if it does. A computation on the current catalogue, not an opinion. 12 undominated of 145 · Oct 6, 2026 [1 · Choose & set workload](#check-input)[2 · Read verdict](#check-verdict)[3 · Inspect alternatives](#check-options) As of Oct 6, 2026, Claude Sonnet 5.5 is dominated for Balanced on LMArena. Muse Spark 1.3 scores 23.3 higher and costs 50% less, with a covering envelope. 12 of 145 rated, priced standard models are undominated. [Inspect model evidence](/models/anthropic__claude-sonnet-5.5/) [Compare differences & requirements](/compare/?models=anthropic%2Fclaude-sonnet-5.5%2Cmeta%2Fmuse-spark-1.3) Current model Claude Sonnet 5.5 Balanced 3 tokens in per 1 out Balanced Summarise Chat Code gen Agentic Monthly spend (USD) Used only to say how many months a named switching cost would take to earn back. Leave blank to skip. Switching cost (USD) Muse Spark 1.3 is both better and cheaper than Claude Sonnet 5.5: 23.3 points higher on LMArena and 50% less per million tokens, $2.00 cheaper at this mix. [Claude Sonnet 5.5](https://undominated.ai/models/anthropic__claude-sonnet-5.5/) LMArena Elo · higher is better Scale starts at 1040 Elo ** 1466.6 Effective $/M · Balanced · lower is better ** $4.00/M [Muse Spark 1.3](https://undominated.ai/models/meta__muse-spark-1.3/) LMArena Elo · higher is better Scale starts at 1040 Elo ** 1489.9 Effective $/M · Balanced · lower is better ** $2.00/M Claude Sonnet 5.5 takes text, image, file, returns up to 128,000 tokens from a 1,000,000-token context, and is listed by 8 sellers. Compared against 145 rated, priced models on this lens: 3 models dominate it and give up nothing, 5 more dominate it but give something up. Claude Sonnet 5.5 scores 1466.6 at $4.00 per million tokens for this mix. ## Envelope-safe replacements Each row scores at least as high, costs no more, and covers this model’s context, output, modalities, tools, and reasoning. A cheaper narrower model is not listed here. | Model | LMArena | Effective $/M | You save | | --- | --- | --- | --- | | [Muse Spark 1.3](/models/meta__muse-spark-1.3/) | 1489.9 +23.3 | $2.00/M | 50% | | [Muse Spark 1.2](/models/meta__muse-spark-1.2/) | 1483.2 +16.6 | $2.00/M | 50% | | [Muse Spark 1.1](/models/meta__muse-spark-1.1/) | 1479.2 +12.6 | $2.00/M | 50% | ## Higher score, lower price, named losses Not a drop-in. The loss is why these are not a recommendation. | Model | LMArena | Effective $/M | You give up | | --- | --- | --- | --- | | [Gemini 3.8 Flash](/models/google__gemini-3.8-flash/) | 1497.0 | $3.00/M | max output | | [MiMo-V2.6-Pro](/models/xiaomi__mimo-v2.6-pro/) | 1491.0 | $0.540/M | file | | [Gemini 3.7 Flash](/models/google__gemini-3.7-flash/) | 1487.0 | $3.00/M | max output | | [Gemini 3.6 Flash](/models/google__gemini-3.6-flash/) | 1479.5 | $1.50/M | max output | | [Gemini 3.5 Flash](/models/google__gemini-3.5-flash/) | 1477.7 | $3.38/M | max output | 145 rated, priced standard models. Chartreuse is the frontier. Cobalt is the model you named, when it is not on the staircase. Copy watch URL [Open the frontier](/frontier/) The link keeps the model and mix, using the current catalogue. Monthly spend and switching cost stay in this browser tab and are left out of the link. ## Saved decision references Save the model, workload, catalogue date and capability-preservation rule in this browser. Spend, switching cost and bill contents are not saved. No account or notifications. Constraint: replacements must preserve the model’s capabilities; any losses remain named trade-offs. Historical decisions cannot be fully replayed from saved references: past prices, scores and capability evidence are not stored. Save this reference ## Continue your investigation - [Build a shortlist](/compare/) - [Inspect alternatives](/alternatives/) - [Check billing conditions](/traps/) - [Read model evidence](/models/)