GPT-5.1 API pricing
GPT-5.1 costs $1.25 per million input tokens and $10 per million output tokens on OpenAI's API. Input read back from the prompt cache costs $0.125 per million. A typical support chat reply (1,500 tokens in, 300 out) costs about $0.0049.
| Input | $1.25 per 1M tokens |
|---|---|
| Output | $10 per 1M tokens |
| Cached input | $0.125 per 1M tokens |
| Context window | 400K tokens |
| Reads | images, text, files |
| Released | November 13, 2025 |
What requests cost on GPT-5.1
The same four requests on every page, so you can compare models directly.
| Request | Tokens in / out | Per request | Per 10,000 requests |
|---|---|---|---|
| A support chat reply | 1,500 / 300 | $0.0049 | $48.75 |
| Summarizing a 10-page document | 6,000 / 500 | $0.013 | $125 |
| Sorting a support ticket into a category | 400 / 5 | $0.00055 | $5.50 |
| A question about a 120-page document | 60,000 / 800 | $0.083 | $830 |
OpenAI's cheapest model here, GPT-5 nano, costs 96% less for the same chat reply. Whether it is good enough depends on the request: simple ones (sorting, short summaries, extraction) often are, hard reasoning often isn't.
Other OpenAI models
| Model | Input | Output | A chat reply | Next to GPT-5.1 |
|---|---|---|---|---|
| GPT-5 nano | $0.05 | $0.40 | $0.00019 | 96% less |
| GPT-4.1 nano | $0.10 | $0.40 | $0.00027 | 94% less |
| GPT-6 Luna | $0.10 | $0.50 | $0.00030 | 94% less |
| GPT-4o mini | $0.15 | $0.60 | $0.00040 | 92% less |
| GPT-5.6 Luna | $0.20 | $1.20 | $0.00066 | 86% less |
| GPT-5.4 nano | $0.20 | $1.25 | $0.00068 | 86% less |
| GPT-5 mini | $0.25 | $2 | $0.00097 | 80% less |
| GPT-4.1 mini | $0.40 | $1.60 | $0.0011 | 78% less |
| GPT-5.4 mini | $0.75 | $4.50 | $0.0025 | 49% less |
| o4-mini | $1.10 | $4.40 | $0.0030 | 39% less |
| o3-mini | $1.10 | $4.40 | $0.0030 | 39% less |
| GPT-5 | $1.25 | $10 | $0.0049 | same price |
| GPT-4.1 | $2 | $8 | $0.0054 | 11% more |
| o3 | $2 | $8 | $0.0054 | 11% more |
| GPT-6.1 Sol | $2 | $10 | $0.0060 | 23% more |
| GPT-6 Sol | $2 | $10 | $0.0060 | 23% more |
| GPT-5.6 Terra | $2 | $12 | $0.0066 | 35% more |
| GPT-4o | $2.50 | $10 | $0.0067 | 38% more |
| GPT-5.2 | $1.75 | $14 | $0.0068 | 40% more |
| GPT-5.4 | $2.50 | $15 | $0.0083 | 69% more |
| GPT-5.6 Sol | $4 | $20 | $0.012 | 2.5x the price |
| GPT-5.5 | $5 | $30 | $0.017 | 3.4x the price |
| GPT-6 Astra | $10 | $50 | $0.03 | 6.2x the price |
| o1 | $15 | $60 | $0.041 | 8.3x the price |
| o3-pro | $20 | $80 | $0.054 | 11x the price |
| GPT-5 Pro | $15 | $120 | $0.059 | 12x the price |
| GPT-5.2 Pro | $21 | $168 | $0.082 | 17x the price |
| GPT-5.5 Pro | $30 | $180 | $0.099 | 20x the price |
| GPT-5.4 Pro | $30 | $180 | $0.099 | 20x the price |
| o1-pro | $150 | $600 | $0.405 | 83x the price |
Similar price from other companies
| Model | Input | Output | A chat reply | Next to GPT-5.1 |
|---|---|---|---|---|
| Gemini 2.5 Pro | $1.25 | $10 | $0.0049 | same price |
| Grok 4.7 | $2 | $6 | $0.0048 | 2% less |
| Grok 4.6 | $2 | $6 | $0.0048 | 2% less |
| Grok 4.5 | $2 | $6 | $0.0048 | 2% less |
| Claude Sonnet 5.5 | $2 | $10 | $0.0060 | 23% more |
Paying GPT-5.1 prices for every request?
Most apps send simple requests to the same strong model as the hard ones. PromptUnit checks each request your app sends and uses a cheaper model only when it is just as good for that request. You pay 20% of what it saves, and nothing if it saves nothing.
Checked October 14, 2026. Prices are read every day from OpenAI's pricing page. Context window, inputs and release date come from OpenRouter's public model list.
These are the standard list prices on each provider's own API. Batch, flex and priority tiers, cloud platforms such as Amazon Bedrock or Google Vertex AI, and regional endpoints are priced differently. Request costs above count input and output tokens only, not cache, search or image fees.