Cheaper alternatives to Claude Sonnet 5.5
Claude Sonnet 5.5 costs $2 / $10 per 1M input / output tokens and scores 167 on Epoch AI’s Capabilities Index. 2 current models score within its margin of error for less, the cheapest being Claude Haiku 5.5 at 95% less. Prices checked 13 Oct – 6 Nov 2026.
Similar capability, lower price
Highest score first
| Model | Capability | Input / output per 1M | Cheaper by | Customer chat assistant, a month | Compare |
|---|---|---|---|---|---|
 GPT-6.1 TerraOpenAI |
168level, within the margin | $1.00 / $5.00 | 50% | $153 | Compare |
 Claude Haiku 5.5Anthropic |
160level, within the margin | $0.10 / $0.50 | 95% | $15.50 | Compare |
A step down, for much less
Highest score first
| Model | Capability | Input / output per 1M | Cheaper by | Customer chat assistant, a month | Compare |
|---|---|---|---|---|---|
 Gemini 3.8 FlashGoogle |
1589 below | $0.75 / $3.75 | 63% | $116 | Compare |
 Qwen3.8 MaxAlibaba |
1589 below | $2.00 / $6.00 | 25% | $320 | Compare |
| GPT-6 LunaOpenAI |
15710 below | $0.10 / $0.50 | 95% | $15.50 | Compare |
 Muse Spark 1.3Meta |
15710 below | $1.25 / $4.25 | 50% | $155 | Compare |
 DeepSeek V4.1 FlashDeepSeek |
15611 below | $0.30 / $1.20 | 87% | $39.30 | Compare |
 GLM-5.3Z.ai |
15611 below | $1.40 / $4.40 | 46% | $171 | Compare |
 Grok 4.7xAI |
15512 below | $2.00 / $6.00 | 25% | $245 | Compare |
Other workhorse models, not yet scored
| Model | Capability | Input / output per 1M | Cheaper by | Customer chat assistant, a month | Compare |
|---|---|---|---|---|---|
 Nemotron 3 SuperNVIDIA · open weights · via OpenRouter |
Not scored | $0.085 / $0.40 | 96% | $16.50 | Compare |
 Command A+Cohere |
Not scored | $0.30 / $1.50 | 85% | $52.50 | Compare |
What switching saves on three workloads
Per month, list prices
| Workload | Claude Sonnet 5.5 | Claude Haiku 5.5 | Gemini 3.8 Flash |
|---|---|---|---|
| Customer chat assistant100M in, 20M out, 50% cached | $305 | $15.50 | $116 |
| Document Q&A (RAG)240M in, 12M out, 30% cached | $463 | $23.52 | $176 |
| Coding agent750M in, 8M out, 85% cached | $369 | $21.63 | $162 |
Monthly cost at list prices with no batch discount. Your own numbers: open these models in the cost calculator.
How to choose
- Same quality, smaller bill: Claude Haiku 5.5 scores level with Claude Sonnet 5.5 and costs 95% less. Test it on your hardest prompts first.
- Stay with Anthropic: Claude Haiku 5.5 keeps the same API, tools and data terms at $0.10 / $0.50.
- Mix models: send routine requests to a cheaper model and keep Claude Sonnet 5.5 for the hard ones. How much that saves depends on your traffic, so measure quality on a sample before switching everything.
- Cut the bill without switching: batch processing and prompt caching often save more than changing model. See how to cut your API bill in half.
Questions
What is the cheapest alternative to Claude Sonnet 5.5 with similar capability?
Claude Haiku 5.5 from Anthropic, at $0.10 / $0.50 per 1M input / output tokens, 95% less than Claude Sonnet 5.5 at a typical 3:1 mix. On Epoch AI’s Capabilities Index it scores 160 against 167, within the margin of error.
Is GPT-6.1 Terra as good as Claude Sonnet 5.5?
On general benchmarks, they’re level: Epoch AI’s Capabilities Index gives GPT-6.1 Terra 168 (range 165–173) and Claude Sonnet 5.5 167 (164–171). Benchmarks don’t cover every task, so run both on a sample of your own work before switching.
How much would I save by switching from Claude Sonnet 5.5?
For a customer chat assistant (100M input and 20M output tokens a month, half the input cached), Claude Sonnet 5.5 costs $305 a month. Claude Haiku 5.5 costs $15.50, Claude Haiku 5.5 $15.50.
Is there a cheaper Anthropic model than Claude Sonnet 5.5?
Yes: Claude Haiku 5.5 ($0.10 / $0.50, capability 160). Staying with Anthropic keeps your prompts, tools and billing the same.
Why isn’t every cheaper model listed?
We list current models that cost less than Claude Sonnet 5.5 at a 3:1 input-to-output mix and either score within about 12 points of it on Epoch AI’s index or are in the same tier without a score yet. Much weaker models are cheaper still but rarely a like-for-like swap.
Capability: Epoch Capabilities Index by Epoch AI, CC BY 4.0, read 4 Nov 2026. Prices from each provider’s own page, linked on every model page.