Claude Sonnet 4 vs Claude Sonnet 3.7
Anthropic's flagship versus its previous-gen — when does the upgrade earn back the cost?
Anthropic's strongest Sonnet — deep, careful, long-form.
Half the cost of Sonnet 4, most of the quality.
TL;DR
Sonnet 3.7 is the better daily driver. Most everyday tasks don't show the gap.
Reach for Sonnet 4 on hard reasoning, multi-file code refactors, or long creative writing where output quality really matters.
Token cost: Sonnet 4 is roughly 4x more expensive per token than 3.7. On AskAI.free, both are unlocked by Pro and Max — your monthly token budget burns faster with Sonnet 4.
Side-by-side specs
| Claude Sonnet 4 | Claude Sonnet 3.7 | |
|---|---|---|
| Vendor | Anthropic | Anthropic |
| Context window | 200K tokens | 200K tokens |
| Image input | ✓ Yes | ✓ Yes |
| Voice mode | — No | — No |
| Web search | — No | — No |
| Knowledge cutoff | April 2024 | Nov 2024 |
| Best for | Long-form writing, document analysis, multi-file coding, nuanced instructions | Daily writing, document summaries, general coding |
| Available on AskAI.free | Pro/Max on AskAI.free | Pro/Max on AskAI.free |
Winner by task
| Task | Winner | Why |
|---|---|---|
| Quick everyday questions | Claude Sonnet 3.7 | 3.7 is fast enough and the gap is invisible. |
| Long-form creative writing | Claude Sonnet 4 | Sonnet 4's prose is noticeably better. |
| Hardest reasoning tasks | Claude Sonnet 4 | This is where the upgrade earns its cost. |
| Coding (single file) | Claude Sonnet 3.7 | 3.7 handles most coding tasks fine. |
| Coding (multi-file refactor) | Claude Sonnet 4 | Sonnet 4 reasons about systems better. |
| Speed | Claude Sonnet 3.7 | Notably faster. |
| Price | Claude Sonnet 3.7 | ~4x cheaper per token. |
| Token budget on Pro plan | Claude Sonnet 3.7 | Stretches your monthly tokens further. |
Real-world use cases
Drafting daily emails
Sonnet 3.7. The quality is identical for short-form writing; you're paying 4x for a benefit you can't see.
Writing a book chapter
Sonnet 4. The narrative coherence over thousands of words is meaningfully better.
Refactoring a 500-line function
Sonnet 4. Worth the token cost — fewer mistakes, better suggestions.
Asking 'fix this typo'
Sonnet 3.7. Anything would work. Don't waste Sonnet 4 tokens on this.
Stop reading. Try both side-by-side on AskAI.free — your first question is free.
Start a free chat →Frequently asked questions
Is Sonnet 4 worth 4x the cost?
For most users, no — Sonnet 3.7 covers everyday tasks. Reach for Sonnet 4 on hard reasoning, complex code, or important writing where quality matters.
Can I switch between them mid-conversation?
Yes, on AskAI.free the model picker lets you switch within a single chat.
Which has the larger context window?
Both support 200K tokens — same context window, different output quality.