Claude Sonnet 4.5 vs GPT-5 Nano
A side-by-side comparison of two multimodal models — real specs, pricing, strengths and weaknesses, and a clear verdict on which to choose. Kept current by our agents.
Quick verdict: which should you choose?
Choose Claude Sonnet 4.5 if you need
- ✓Need the lowest cost at $0.4 per million tokens for frequent multimodal queries
- ✓Require fast output at 170.06 tokens per second with 400k context for extended documents
- ✓Want lightweight multimodal handling of text, image, and file inputs without heavy reasoning demands
- ✓Prioritize efficient large-context processing over maximum context length or safety features
Choose GPT-5 Nano if you need
- ✓Need the largest 1M context window for very extensive multimodal analysis
- ✓Value strong safety alignment and careful, detailed reasoning on complex inputs
- ✓Require reliable handling of large contexts with effective multimodal file support
- ✓Accept higher cost and potential verbosity in exchange for cautious output quality
Verdict
GPT-5 Nano leads on price and measured speed while supporting multimodal inputs in a 400k context, making it practical for high-volume document work. Claude Sonnet 4.5 offers a larger 1M context and emphasizes careful multimodal reasoning plus safety alignment, though its $15/1M price is substantially higher and speed/intelligence metrics are unreported. The choice hinges on whether cost and throughput outweigh maximum context size and cautious analysis.
Claude Sonnet 4.5 vs GPT-5 Nano: side by side
| Spec | Claude Sonnet 4.5 | GPT-5 Nano | Winner |
|---|---|---|---|
| Intelligence | — | 26.8 | Tie |
| Output speed | — | 170 t/s | Tie |
| Output price | $15.00/1M | $0.40/1M | GPT-5 Nano |
| Context | 1000K | 400K | Claude Sonnet 4.5 |
| Params | — | — | Tie |
| Type | Proprietary | Proprietary | Tie |
| Provider | Anthropic | OpenAI | Tie |
Detailed analysis
Pricing
Winner: GPT-5 NanoGPT-5 Nano is listed at $0.4 per million output tokens. Claude Sonnet 4.5 costs $15 per million output tokens, making GPT-5 Nano over 37 times cheaper on the given metric.
Speed & Efficiency
Winner: GPT-5 NanoGPT-5 Nano reports 170.06 tokens per second output speed and is described as lightweight for faster responses. Claude Sonnet 4.5 has no speed figure provided, though its emphasis on detailed reasoning may imply slower throughput.
Context Length
Winner: Claude Sonnet 4.5Claude Sonnet 4.5 supports a 1M token context. GPT-5 Nano supports 400k tokens, so Claude handles larger-scale inputs despite GPT-5 Nano's noted efficiency within its window.
Reasoning & Safety
Winner: Claude Sonnet 4.5Claude Sonnet 4.5 highlights careful detailed reasoning and strong safety alignment. GPT-5 Nano is noted for lower capability depth and potential struggles with highly complex reasoning.
Claude Sonnet 4.5
Pros
- +Strong safety alignment
- +Reliable handling of large contexts
- +Careful and detailed reasoning
- +Effective multimodal file support
Cons
- –Can be overly cautious with refusals
- –Vision performance varies by image complexity
- –May produce verbose responses
GPT-5 Nano
Pros
- +Handles very large contexts efficiently
- +Supports text, image, and file inputs
- +Lightweight design for faster responses
- +Practical for extended document tasks
Cons
- –Lower capability depth than full-scale models
- –May struggle with highly complex reasoning
- –Trade-off in advanced task performance
Summary: Claude Sonnet 4.5 vs GPT-5 Nano
Select GPT-5 Nano when price, speed, and practical 400k multimodal document tasks are priorities. Choose Claude Sonnet 4.5 when maximum 1M context and safety-focused reasoning matter more than cost. The data show clear trade-offs with no single dominant model across all dimensions.
Frequently asked questions
GPT-5 Nano at $0.4 per million output tokens versus Claude Sonnet 4.5 at $15 per million.