Claude Sonnet 4.5 vs o3
Compare Anthropic and OpenAI AI models
Cost Comparison (1000 input + 500 output tokens, 100 requests/day)
Claude Sonnet 4.5
o3
Cost Differences
o3 costs less than Claude Sonnet 4.5
Feature Comparison
| Feature | Claude Sonnet 4.5 | o3 |
|---|---|---|
| Provider | Anthropic | OpenAI |
| Input Price | $3.00/1M tokens | $2.00/1M tokens |
| Output Price | $15.00/1M tokens | $8.00/1M tokens |
| Context Window | 200,000 tokens | 1,000,000 tokens |
| Max Output | 64,000 tokens | 131,072 tokens |
| Category | balanced | reasoning |
| Capabilities | textvisioncode | textreasoningvisioncode |
| Release Date | 9/29/2025 | 4/16/2025 |
Claude Sonnet 4.5 vs o3: Which Should You Choose?
Choosing between Claude Sonnet 4.5 and o3 depends on your priorities: cost efficiency, context length, or raw capability. o3 is the more affordable option at $2.00/1M input tokens — 33% cheaper than Claude Sonnet 4.5. Meanwhile, o3 offers a significantly larger context window at 1,000,000 tokens vs 200,000 for Claude Sonnet 4.5.
These models come from different providers — Anthropic and OpenAI — which means different API ecosystems, SDKs, rate limits, and terms of service. If you're already integrated with Anthropic, switching to OpenAIinvolves migration effort beyond just pricing. Factor in your existing infrastructure when deciding.
These models target different tiers: Claude Sonnet 4.5 is a balanced model while o3 is reasoning. This means they're optimized for different workloads. o3 targets more demanding workloads, while Claude Sonnet 4.5 provides a cost-effective option for everyday tasks.
Output costs matter too. Claude Sonnet 4.5 charges $15.00/1M output tokens vs $8.00 for o3. For generation-heavy workloads (content creation, code generation, summarization), output pricing often dominates your bill. o3 has the edge here at $8.00/1M output tokens.
Multimodal capabilities: Both models support vision (image understanding), so you can send images alongside text prompts with either option.
Best Use Cases
Choose Claude Sonnet 4.5 when:
- • You're already using Anthropic's API ecosystem
Choose o3 when:
- • Budget is a primary concern
- • You need a larger context window (1,000,000 tokens)
- • You need more capabilities (reasoning)
- • You need longer outputs (up to 131,072 tokens)
- • You're already using OpenAI's API ecosystem
Try Different Scenarios
Use the calculator below to see how costs change with different usage patterns
Claude Sonnet 4.5 (Anthropic)
o3 (OpenAI)
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