GPT 5.1 API Pricing
GPT 5.1 costs $1.25 per 1M input tokens and $10.00 per 1M output tokens on OpenAI's API. Cached input is billed at $0.125 per 1M tokens. Prices are provider list prices in USD, refreshed as sources update; see the GPT 5.1 model profile for capability scores.
Price List
| Rate | Price (USD) | Notes |
|---|---|---|
| Input | $1.25 | per 1M tokens |
| Output | $10.00 | per 1M tokens |
| Cached input (read) | $0.125 | per 1M tokens |
| Blended input + output | $11.25 | 1M in + 1M out at list price |
What a Workload Costs
Computed straight from the list prices above — token counts are illustrative workload sizes, not measurements of GPT 5.1.
| Workload | Cost | Tokens |
|---|---|---|
| Short chat turn | $0.00625 | 1K in / 500 out |
| Summarize a long document | $0.145 | 100K in / 2K out |
| Agentic coding session | $1.63 | 500K in / 100K out |
| 1M input + 1M output tokens | $11.25 | 1M in / 1M out |
Effective Cost
In AI IQ's scoring, GPT 5.1's list price is adjusted by a token-usage multiplier of 0.833 (measured from real benchmark runs), giving an effective cost of $9.37 per 1M input + output tokens. That places it #81 of 117 models on the effective-cost ranking (lower is cheaper). Some models spend far more tokens than others on the same task, so effective cost compares what a unit of work really costs. Method details are on the methodology page; see all models on the cost charts and the falling cost of intelligence over time.
Cheaper Alternatives at Similar Capability
Models with a lower effective cost that score within a few IQ points of GPT 5.1 (IQ 111), or better.
| Model | Provider | IQ | Effective Cost / 1M |
|---|---|---|---|
| gpt-5.6-luna | OpenAI | 129 | $9.29 |
| Muse Spark 1.2 | Meta | 122 | $4.19 |
| GLM-5.3-Flash | Z.ai | 121 | $4.99 |
| glm-5.2 | Z.ai | 120 | $7.28 |
| muse-spark-1.1 | Meta | 119 | $4.19 |
| kimi-k2.6 | Kimi | 119 | $4.50 |