Anthropic: Claude Sonnet 4.6 vs OpenAI: o3 Pro
Head-to-head API pricing and cost comparison between Anthropic’s Anthropic: Claude Sonnet 4.6 and OpenAI’s OpenAI: o3 Pro. Prices auto-refresh daily from OpenRouter.
Anthropic: Claude Sonnet 4.6 is 85% cheaper for input tokens; Anthropic: Claude Sonnet 4.6 also wins on output tokens.
Side-by-side comparison
| Spec | Anthropic: Claude Sonnet 4.6 | OpenAI: o3 Pro |
|---|---|---|
| Input price (per 1M) | $3.00 | $20.00 |
| Cached input (per 1M) | $0.30 | — |
| Output price (per 1M) | $15.00 | $80.00 |
| Batch input (per 1M) | $1.50 | $10.00 |
| Batch output (per 1M) | $7.50 | $40.00 |
| Reasoning price (per 1M) | — | — |
| Context window | 1000K | 200K |
| Vision support | Yes | Yes |
| Caching support | Yes | No |
| Batch API | Yes | Yes |
| Reasoning capability | No | Yes |
Monthly cost at volume
Estimated monthly API spend at common production traffic levels (input/output tokens per request shown).
| Volume | Anthropic: Claude Sonnet 4.6 | OpenAI: o3 Pro | Savings |
|---|---|---|---|
1K req/day 500in / 200out tokens | $135.00 | $780.00 | $645.00 Anthropic: Claude Sonnet 4.6 wins |
10K req/day 1500in / 500out tokens | $3,600 | $21,000 | $17,400 Anthropic: Claude Sonnet 4.6 wins |
100K req/day 3000in / 800out tokens | $63,000 | $372,000 | $309,000 Anthropic: Claude Sonnet 4.6 wins |
1M req/day 8000in / 2000out tokens | $1,620,000 | $9,600,000 | $7,980,000 Anthropic: Claude Sonnet 4.6 wins |
Adjust input/output token counts, request volume, batch & cached pricing.
Related comparisons
Frequently asked questions
Which is cheaper, Anthropic: Claude Sonnet 4.6 or OpenAI: o3 Pro?
For input tokens, Anthropic: Claude Sonnet 4.6 is roughly 85% cheaper at $3.00/1M vs $20.00/1M. For output tokens, Anthropic: Claude Sonnet 4.6 wins at $15.00/1M. Real-world cost depends on your input/output ratio — use the calculator to model your actual workload.
What’s the context window difference?
Anthropic: Claude Sonnet 4.6 has a context window of 1000K tokens. OpenAI: o3 Pro offers 200K tokens. Larger context windows are valuable for long documents, RAG pipelines, and multi-turn conversations — but they come with higher input-token bills if you fill them every request.
Should I use Anthropic: Claude Sonnet 4.6 or OpenAI: o3 Pro?
Choose Anthropic: Claude Sonnet 4.6 if you’re already on the Anthropic stack, want broad ecosystem support, or prefer its lower input price. Choose OpenAI: o3 Pro for OpenAI’s ecosystem, native vision input, or its differentiated capabilities. Run a small benchmark on your own prompts before committing — price is only one axis.
How are these prices kept current?
Prices are pulled directly from OpenRouter’s public models API once every 24 hours via a Convex cron job, then normalized to per-1M-token figures. Last refresh: Apr 21, 2026.