// alternatives · October 2026
Claude Sonnet 5.5 alternatives
Cheaper models that come close, budget substitutes, and the cheapest step up — chosen on published LiveBench scores and live list price, never on our opinion. Every model here supports tool calling and image input, as Claude Sonnet 5.5 does.
The closest cheaper alternative to Claude Sonnet 5.5 is GPT-6.1 Terra — 2.2 points lower overall, 50% cheaper on LiveBench and list price.
Claude Sonnet 5.5: 80.0 overall on LiveBench, $4.00 per 1M blended tokens, about $1,440/mo for a RAG assistant.
Cheaper, close in quality
Lower list price and within 5 points of Claude Sonnet 5.5 on LiveBench overall — the switches least likely to be noticed by users. Strongest first.
| Model | Overall | vs Claude Sonnet 5.5 | Blended / 1M | RAG assistant | Context |
|---|---|---|---|---|---|
| GPT-6.1 Terraopenai 2.2 points lower overall, 50% cheaper. Head to head → | 77.8 | −2.2 | $2.00−50% | $720.00/mo | 1.1M |
Budget substitutes
Within 15 points of Claude Sonnet 5.5, cheapest first — and only models that are the best score at their price, so nothing here is beaten by a cheaper pick. Worth testing for high-volume traffic where the last few points matter less than the bill.
| Model | Overall | vs Claude Sonnet 5.5 | Blended / 1M | RAG assistant | Context |
|---|---|---|---|---|---|
| Claude Haiku 5.5anthropic 10.2 points lower overall, 95% cheaper. Head to head → | 69.8 | −10.2 | $0.200−95% | $74.00/mo | 1M |
| DeepSeek V4.1 Flash 1017deepseek 6.0 points lower overall, 87% cheaper. Head to head → | 74.0 | −6.0 | $0.525−87% | $194.40/mo | 1.0M |
Match it on one task for less
For each LiveBench category, the cheapest model that scores at least as well as Claude Sonnet 5.5 there. Useful when your workload is mostly one kind of task.
| Category | Cheapest match | Score | Blended / 1M |
|---|---|---|---|
| Coding | DeepSeek V4.1 Flash 1017 | 96.0 vs 94.7 | $0.525−87% |
| Browser | GPT-6.1 Terra | 93.1 vs 89.3 | $2.00−50% |
| Data analysis | GPT-6 Luna | 73.4 vs 59.5 | $0.200−95% |
| Research | SpaceXAI: Grok 4.7 | 86.4 vs 83.6 | $3.00−25% |
Stronger options, cheapest first
Models that beat Claude Sonnet 5.5 on LiveBench overall, ordered by what the upgrade costs.
| Model | Overall | vs Claude Sonnet 5.5 | Blended / 1M | RAG assistant | Context |
|---|---|---|---|---|---|
| GPT-6.1 Solopenai 4.0 points higher overall, the same list price. Head to head → | 84.1 | +4.0 | $4.00 | $1,440/mo | 1.1M |
| Claude Opus 5.5anthropic 5.1 points higher overall, 100% more expensive. Head to head → | 85.1 | +5.1 | $8.00 | $2,880/mo | 1M |
| GPT-6 Astraopenai 5.6 points higher overall, 400% more expensive. Head to head → | 85.6 | +5.6 | $20.00 | $7,400/mo | 1.1M |
| Claude Fable 5.1anthropic 5.7 points higher overall, 400% more expensive. Head to head → | 85.7 | +5.7 | $20.00 | $7,100/mo | 1M |
Claude Sonnet 5.5 alternatives FAQ
What is the best alternative to Claude Sonnet 5.5?
GPT-6.1 Terra. 2.2 points lower overall, 50% cheaper. Every suggestion supports tool calling and image input, like Claude Sonnet 5.5.
What is the cheapest alternative to Claude Sonnet 5.5?
Claude Haiku 5.5 at $0.200 per 1M blended tokens, scoring 69.8 overall against Claude Sonnet 5.5's 80.0. On a RAG assistant at 100K requests a month that is $74.00 instead of $1,440.
Which model is better than Claude Sonnet 5.5?
The cheapest model that scores higher overall on LiveBench is GPT-6.1 Sol — 4.0 points higher overall, the same list price.
Is there a cheaper model that matches Claude Sonnet 5.5 on specific tasks?
Yes, in 4 of the seven LiveBench categories. For example, coding: DeepSeek V4.1 Flash 1017 (96.0 vs 94.7); browser: GPT-6.1 Terra (93.1 vs 89.3); data analysis: GPT-6 Luna (73.4 vs 59.5).
How alternatives are chosen
- Scores — LiveBench release 2026-10-25. Only models with a published run are suggested on quality; a missing model means “not evaluated”, not “worse”.
- Prices — live list prices from OpenRouter, blended 3:1 input:output. Monthly figures price a RAG assistant with the published cached-input rate where there is one.
- Same job — suggestions must support every capability Claude Sonnet 5.5 has among tool calling and image input. Other listings of the same model (free or batch tiers) are variants, not alternatives, and are left out.
A few points on a public benchmark can hide large differences on your own tasks. Shortlist here, then decide with an eval — how to build one.