Claude Sonnet 4 vs Sonnet 5: the older one costs 1.5× more
Short answer: Claude Sonnet 4.x costs $3 per million input tokens and $15 per million output tokens. Claude Sonnet 5 costs $2 and $10. Staying on Sonnet 4 means paying 50% more for the same number of tokens.
| Model | Input, per 1M | Output, per 1M | vs Sonnet 5 |
|---|---|---|---|
| Claude Sonnet 4.x | $3 | $15 | 1.5× |
| Claude Sonnet 5 | $2 | $10 | 1× |
What it means in dollars
At $6,000 a month on Sonnet 4.x, the same tokens on Sonnet 5 would cost about $4,000. That is $2,000 a month, or $24,000 a year, for changing one model name.
How to check your own bill
- Export last month's cost file from the Claude Console.
- Drop it on AI Spend Doctor. Nothing is uploaded.
- You will see how much went to Sonnet 4.x and what it would cost on Sonnet 5.
Check your own bill in 30 seconds
Questions
How much cheaper is Claude Sonnet 5 than Sonnet 4?
Sonnet 5 is a third cheaper: $2 versus $3 per million input tokens and $10 versus $15 per million output tokens. Put the other way, Sonnet 4 costs 1.5 times more.
Should I switch from Sonnet 4 to Sonnet 5?
Usually yes on price. Run your own evaluation set first to confirm output quality for your tasks.
List prices checked 25 September 2026 on the official Anthropic pricing page. Test quality on your own tasks before switching models. © 2026 Valeriy Danilov. AI Spend Doctor by AgentBridge Labs.