Cost Comparison (1000 input + 500 output tokens, 100 requests/day)
GPT-4o
GPT-5.1
Cost Differences
GPT-5.1 costs less than GPT-4o
Feature Comparison
| Feature | GPT-4o | GPT-5.1 |
|---|---|---|
| Provider | OpenAI | OpenAI |
| Input Price | $2.50/1M tokens | $1.25/1M tokens |
| Output Price | $10.00/1M tokens | $10.00/1M tokens |
| Context Window | 128,000 tokens | 1,000,000 tokens |
| Max Output | 16,384 tokens | 131,072 tokens |
| Category | flagship | flagship |
| Capabilities | textvisionaudio | textvisionaudiocodereasoning |
| Release Date | 5/13/2024 | 11/12/2025 |
GPT-4o vs GPT-5.1: Which Should You Choose?
Choosing between GPT-4o and GPT-5.1 depends on your priorities: cost efficiency, context length, or raw capability. GPT-5.1 is the more affordable option at $1.25/1M input tokens — 50% cheaper than GPT-4o. Meanwhile, GPT-5.1 offers a significantly larger context window at 1,000,000 tokens vs 128,000 for GPT-4o.
Both models are in the flagship category, making this a direct head-to-head comparison. At scale — say 10,000 requests per day — the cost difference adds up: GPT-5.1 would save you roughly $375.00/month compared to GPT-4o. For startups and indie developers, that difference can be significant.
Output costs matter too. GPT-4o charges $10.00/1M output tokens vs $10.00 for GPT-5.1.
Multimodal capabilities: Both models support vision (image understanding), so you can send images alongside text prompts with either option.
Best Use Cases
Choose GPT-4o when:
- • You're already using OpenAI's API ecosystem
Choose GPT-5.1 when:
- • Budget is a primary concern
- • You need a larger context window (1,000,000 tokens)
- • You need more capabilities (code, 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
GPT-4o (OpenAI)
GPT-5.1 (OpenAI)
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