GPT-5.1 vs GPT-5.5 Pro
GPT-5.1 vs GPT-5.5 Pro: GPT-5.1 is cheaper for input-heavy usage ($1.25/M vs $30.00/M input tokens), while GPT-5.5 Pro is better for long-context tasks (1,050,000 tokens).
Direct answer: choose GPT-5.1 for lower token spend and choose GPT-5.5 Pro when your workload needs longer context.
Common pricing searches covered on this page: GPT-5.1 vs GPT-5.5 Pro • GPT-5.1 vs GPT-5.5 Pro pricing • GPT-5.1 vs GPT-5.5 Pro API pricing and 5 1 vs 5 5 pro pricing.
Cost Comparison (1000 input + 500 output tokens, 100 requests/day)
GPT-5.1
GPT-5.5 Pro
Cost Differences
GPT-5.5 Pro costs more than GPT-5.1
Quick Recommendation
Winner for direct API pricing: GPT-5.1. At the default workload, GPT-5.1 saves about $341.25/month ($4,151.875/year) versus GPT-5.5 Pro.
Feature Comparison
| Feature | GPT-5.1 | GPT-5.5 Pro |
|---|---|---|
| Provider | OpenAI | OpenAI |
| Input Price | $1.25/1M tokens | $30.00/1M tokens |
| Output Price | $10.00/1M tokens | $180.00/1M tokens |
| Context Window | 1,000,000 tokens | 1,050,000 tokens |
| Max Output | 131,072 tokens | 128,000 tokens |
| Category | flagship | reasoning |
| Capabilities | textvisionaudiocodereasoning | textvisioncodereasoning |
| Release Date | 11/12/2025 | 4/24/2026 |
GPT-5.1 vs GPT-5.5 Pro: Which Should You Choose?
Choosing between GPT-5.1 and GPT-5.5 Pro 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 — 96% cheaper than GPT-5.5 Pro. Meanwhile, GPT-5.5 Pro offers a significantly larger context window at 1,050,000 tokens vs 1,000,000 for GPT-5.1.
These models target different tiers: GPT-5.1 is a flagship model while GPT-5.5 Pro is reasoning. This means they're optimized for different workloads. GPT-5.1 is built for complex tasks that require deeper reasoning, while GPT-5.5 Pro offers better value for routine operations.
Output costs matter too. GPT-5.1 charges $10.00/1M output tokens vs $180.00 for GPT-5.5 Pro. For generation-heavy workloads (content creation, code generation, summarization), output pricing often dominates your bill. GPT-5.1 has the edge here at $10.00/1M 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 GPT-5.1 when:
- • Budget is a primary concern
- • You need more capabilities (audio)
- • You need longer outputs (up to 131,072 tokens)
- • You're already using OpenAI's API ecosystem
Choose GPT-5.5 Pro when:
- • You need a larger context window (1,050,000 tokens)
- • You're already using OpenAI's API ecosystem
Pros and Caveats at a Glance
GPT-5.1
- • Input pricing: $1.25/M tokens
- • Output pricing: $10.00/M tokens
- • Context window: 1,000,000 tokens
- • Max output: 131,072 tokens
Watch out for
- • Smaller context window than GPT-5.5 Pro
GPT-5.5 Pro
- • Input pricing: $30.00/M tokens
- • Output pricing: $180.00/M tokens
- • Context window: 1,050,000 tokens
- • Max output: 128,000 tokens
Watch out for
- • Higher input cost than GPT-5.1
- • Higher output cost than GPT-5.1
Try Different Scenarios
Use the calculator below to see how costs change with different usage patterns
GPT-5.1 (OpenAI)
GPT-5.5 Pro (OpenAI)
Start using GPT-5.1 today
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Sign Up for OpenAI →Frequently Asked Questions
Which is cheaper, GPT-5.1 or GPT-5.5 Pro?▼
What is the context window difference between GPT-5.1 and GPT-5.5 Pro?▼
Which model is better for AI Agent / Agentic Workflows?▼
Which model has better overall pricing for heavy usage?▼
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