InferIndex · https://inferindex.dev/en/compare/google/gemini-3.1-pro-preview-customtools/vs/openai/gpt-5.6-terra-pro
Gemini 3.1 Pro Preview Custom Tools costs from $4.50 per million tokens and GPT-5.6 Terra Pro from $4.50 (at a 3:1 input:output mix): the cheapest price for each; prices checked on .
Verdict
At these prices, the two models cost about the same per million tokens (at a 3:1 input:output mix).
Each model's lowest blended price, per 1M tokens, across every provider we track.
| Model | Lowest blended price, $ per 1M tokens. Green background: the most favourable value of each column. | Input price of the cheapest offer, per 1M tokens | Output price of the cheapest offer, per 1M tokens | The provider's published policy says the text you send is not used to train models. We only show what is published; we can't check it ourselves. | For 2,000 input tokens and 500 output tokens per request, 1,000 requests a day, at the cheapest offer for that workload. Change the workload above. | Offers | Providers | The maximum amount of text, counted in tokens, the model can take in and write in a single request. Past this limit, the request is refused or cut. | Observation |
|---|---|---|---|---|---|---|---|---|---|
| Most expensive offer · $4.50. The highest blended price among comparable offers: one price per provider (its cheapest route), standard tier, current prices only. Priority tiers and prices converted from points are not counted. | $2.00 | $12.00 | $4.50 | $300.00at NanoGPT | 7 | 5 | 1M | ||
| Most expensive offer · $4.95. The highest blended price among comparable offers: one price per provider (its cheapest route), standard tier, current prices only. Priority tiers and prices converted from points are not counted. | $2.00 | $12.00 | $4.50 | $300.00at NanoGPT | 13 | 5 | 1.1M |
Green background: the most favourable value of each column.
Prices as of Oct 30, 2026, 9:04 PM UTCSame rules as the API's /cheapest route. The monthly estimate uses the cheapest offer for that workload.