AI model comparison
GPT-5.1 vs o3 Pro
Pricing, context window, benchmarks, and features compared side by side. Or skip the guesswork and send one prompt to both.
OpenAI
GPT-5.1
GPT-5.1 is the latest frontier-grade model in the GPT-5 series, offering stronger general-purpose reasoning, improved instruction adherence, and a more natural conversational style compared to GPT-5.
- Input / 1M
- $1.25
- Output / 1M
- $10
- Context
- 400K
OpenAI
o3 Pro
The o-series of models are trained with reinforcement learning to think before they answer and perform complex reasoning.
- Input / 1M
- $20
- Output / 1M
- $80
- Context
- 200K
At a glance
Quick verdict
How the two models stack up on the things people ask about most.
Lower price
GPT-5.1
10.7x cheaper for a typical chat
Higher intelligence score
GPT-5.1
24.7 vs 21.9 on Artificial Analysis
Larger context window
GPT-5.1
400K vs 200K tokens
Newer release
GPT-5.1
Released November 13, 2025
Benchmarks
Benchmark scores
Independent scores from Artificial Analysis. Higher is better.
Intelligence index
GPT-5.124.7o3 Pro21.9Coding index
GPT-5.149.4o3 ProNot availableAgentic index
GPT-5.1Not availableo3 ProNot availablePricing
GPT-5.1 vs o3 Pro API pricing
Per-token API rates. Cheaper option highlighted.
| Metric | GPT-5.1 | o3 Pro |
|---|---|---|
| Input tokensPer 1M tokens | $1.25 | $20 |
| Output tokensPer 1M tokens | $10 | $80 |
| Cached input (read)Per 1M tokens | $0.13 | Not available |
| Cache writePer 1M tokens | Not available | Not available |
| Web searchPer request | $0.01 | $0.01 |
What it costs in practice
Estimated cost per 1,000 requests at standard rates. Coding and long-document figures also show the cost when the input is already cached.
Chat message
2K in, 500 out
GPT-5.1$7.50o3 Pro$80Coding task
30K in, 4K out
GPT-5.1$77.50$43.75 cachedo3 Pro$920Long document summary
150K in, 2K out
GPT-5.1$207.50$38.75 cachedo3 Pro$3160Specs
Context window and capabilities
How much each model can read, how much it can write, and what it accepts as input.
| Metric | GPT-5.1 | o3 Pro |
|---|---|---|
| Context window | 400K tokens | 200K tokens |
| Max output | 128K tokens | 100K tokens |
| Input types | File, Image, Text | File, Image, Text |
| Output types | Text | Text |
| Reasoning effort levels | High, Medium, Low, None | Not available |
| Default reasoning effort | None | Not available |
| Release date | November 13, 2025 | June 10, 2025 |
Features
Supported features
API features available for each model.
| Metric | GPT-5.1 | o3 Pro |
|---|---|---|
| Tool calling | Supported | Supported |
| Structured outputs | Supported | Supported |
| JSON mode | Supported | Supported |
| Reasoning | Supported | Supported |
| Temperature | Not supported | Not supported |
| Stop sequences | Not supported | Not supported |
| Deterministic seed | Supported | Supported |
| Verbosity control | Supported | Not supported |
Keep exploring
More on these models
Other head-to-heads, the full model page, and the alternatives list for each model.
Our take
GPT-5.1 is 10.7x cheaper for a typical chat. GPT-5.1 scores higher on the Artificial Analysis Intelligence Index (24.7 vs 21.9). GPT-5.1 has the larger context window (400K vs 200K tokens). The right pick depends on your workload, so the quickest way to settle it is to send the same prompt to both and compare.
FAQ
Frequently asked questions
Is GPT-5.1 or o3 Pro cheaper?
GPT-5.1 is cheaper for a typical chat (2K input tokens and 500 output tokens). GPT-5.1 costs $1.25 per 1M input tokens and $10 per 1M output tokens, while o3 Pro costs $20 per 1M input tokens and $80 per 1M output tokens.
Which has a bigger context window, GPT-5.1 or o3 Pro?
GPT-5.1 supports up to 400K tokens of context, compared with 200K for o3 Pro.
Is GPT-5.1 smarter than o3 Pro?
On the Artificial Analysis Intelligence Index, GPT-5.1 scores 24.7 and o3 Pro scores 21.9, putting GPT-5.1 ahead. Benchmarks don't capture everything, so the best test is running your own prompts through both.
Can I use GPT-5.1 and o3 Pro at the same time?
Yes. Shortcut Chat sends one prompt to multiple models at once, so you can see GPT-5.1 and o3 Pro answer side by side and keep the better response.
Why choose? Ask both.
Send one prompt to GPT-5.1 and o3 Pro at the same time. Compare the answers side by side and keep the best one.