Published rates rank differently once prompt caching, batch discounts and your own input-to-output ratio are applied. Run both against your numbers.
Claude Sonnet 4.5 vs Claude Sonnet 5.5
Sonnet 4.5 retires on 30 Nov 2026, and its named replacement is a third cheaper.
Monthly cost by workload shape
The same volume costs very different amounts depending on the shape of the traffic. No caching or batch applied.
| Workload | Claude Sonnet 4.5 | Claude Sonnet 5.5 | Difference | |
|---|---|---|---|---|
Customer support chatbot 50K/day · 800 in / 300 out | $10.5K | $7,001.20 | Claude Sonnet 5.5saves $3,500.60 | Model it → |
RAG / search answers 20K/day · 3000 in / 400 out | $9,132.00 | $6,088.00 | Claude Sonnet 5.5saves $3,044.00 | Model it → |
Agent / tool-use loop 8.0K/day · 2500 in / 600 out | $4,018.08 | $2,678.72 | Claude Sonnet 5.5saves $1,339.36 | Model it → |
Batch summarization 100K/day · 5000 in / 500 out | $68.5K | $45.7K | Claude Sonnet 5.5saves $22.8K | Model it → |
Code assistant 15K/day · 2000 in / 800 out | $8,218.80 | $5,479.20 | Claude Sonnet 5.5saves $2,739.60 | Model it → |
Frequently asked questions
Which is cheaper, Claude Sonnet 4.5 or Claude Sonnet 5.5?
At a typical 3:1 input-to-output ratio, Claude Sonnet 5.5 is cheaper: $4.00 blended per 1M tokens against $6.00. That holds at every input:output ratio, one model is cheaper on both rates.
What is the price difference between Claude Sonnet 4.5 and Claude Sonnet 5.5?
Claude Sonnet 4.5: $3.00 input, $15.00 output per 1M tokens. Claude Sonnet 5.5: $2.00 input, $10.00 output. That is 1.5x on input and 1.5x on output.
Does prompt caching change the answer?
Claude Sonnet 4.5 caches input at $0.300/1M and Claude Sonnet 5.5 caches at $0.100/1M. For input-heavy workloads with repeated context, caching can matter more than the base rate difference, model both in the calculator rather than comparing rate cards.
This page compares published prices only. It makes no claim about which model performs better on any task; that depends entirely on your evaluations.
Rate cards decide nothing on their own.
Most teams run several models at once. Finitizer Tokenomics shows what each one actually costs you, read from your own bills and exports, which workloads could test a smaller model, what they would cost on an open-weight model, and, for models you serve yourself, the cost per token beside the API price. A routing decision starts from your spend rather than a price page.
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