Gemini 3.1 Pro Api Vs Gpt-5 Api Per Token Cost
Compare Gemini 3.1 Pro API vs GPT-5 API per token cost Calculator to estimate input and output spend from token counts using current standard API pricing today.
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Gemini 3.1 Pro API vs GPT-5 API per token cost Calculator
TL;DR Summary
The Gemini 3.1 Pro API vs GPT-5 API per token cost Calculator compares estimated API spending from your input and output token counts using current standard pricing. It is a cost estimate, not a billing statement, and the tool does not provide a specific privacy guarantee beyond the information shown on the page.
About This Tool
The Gemini 3.1 Pro API vs GPT-5 API per token cost Calculator is designed for developers, technical teams, AI application builders, and anyone planning API usage who wants to compare token-based model costs. Instead of calculating the price manually, enter the number of input tokens, output tokens, and requests to see the estimated cost for each model.
The calculator focuses on standard API token pricing. For Gemini 3.1 Pro, the standard input price depends on the size of the prompt. Prompts of 200,000 tokens or less use one input rate, while prompts above 200,000 tokens use a higher input rate. Gemini output tokens also have a different rate for prompts above that threshold. GPT-5 uses separate input and output rates under the standard API pricing used by this calculator.
The main inputs are simple. Input Tokens per Request represents the tokens sent to the model. This is commonly called prompt or input token usage. Output Tokens per Request represents the tokens generated by the model. Number of Requests lets you extend the per-request estimate to a larger group of API calls.
All token counts are treated as whole tokens. The calculator does not ask you to enter a dollar rate because the researched standard rates are built into the calculation. This keeps the comparison focused on the current pricing rules used for Gemini 3.1 Pro and GPT-5.
What the Calculator Produces
The calculator provides the estimated Gemini 3.1 Pro cost per request, the estimated GPT-5 cost per request, the estimated total Gemini 3.1 Pro cost for the selected number of requests, the estimated total GPT-5 cost, and the absolute difference between the two estimates.
The result is based on the token counts you enter. If your application uses different token volumes for different requests, you can run the calculator with representative usage or repeat the calculation for separate workloads. A single average token count may not represent an application with highly variable prompts or responses.
How to Use
- Step 1: Enter the number of input tokens used by one API request in the Input Tokens per Request field.
- Step 2: Enter the expected number of output tokens generated by one request.
- Step 3: Enter the number of requests you want included in the total-cost estimate.
- Step 4: Review the Gemini 3.1 Pro and GPT-5 cost estimates shown for one request and for the selected request count.
- Step 5: Use the cost difference as a budgeting reference, while checking the providers' current pricing pages before making a production purchasing decision.
Technical Explanation and Formula
The calculator uses token pricing per 1 million tokens. The basic cost formula is:
API Cost = (Input Tokens ÷ 1,000,000 × Input Rate) + (Output Tokens ÷ 1,000,000 × Output Rate)
For multiple requests:
Total Cost = Cost per Request × Number of Requests
For Gemini 3.1 Pro standard pricing, the calculator uses an input rate of $2.00 per 1 million tokens and an output rate of $12.00 per 1 million tokens when the prompt is 200,000 tokens or less. When the prompt exceeds 200,000 tokens, the input rate becomes $4.00 per 1 million tokens and the output rate becomes $18.00 per 1 million tokens.
For GPT-5 standard API pricing, the calculator uses $1.25 per 1 million input tokens and $10.00 per 1 million output tokens.
These rates are applied separately to input and output usage. The calculator does not treat all tokens as having one blended price. This matters because input and output tokens have different rates for both models.
For example, suppose one request uses 100,000 input tokens and 10,000 output tokens. Because the Gemini prompt is below the 200,000-token threshold, the Gemini estimate is:
(100,000 ÷ 1,000,000 × $2.00) + (10,000 ÷ 1,000,000 × $12.00) = $0.32
The GPT-5 estimate for the same token counts is:
(100,000 ÷ 1,000,000 × $1.25) + (10,000 ÷ 1,000,000 × $10.00) = $0.225
If the same request is made 1,000 times, the estimates become $320.00 for Gemini 3.1 Pro and $225.00 for GPT-5 under the pricing assumptions used here.
A second example shows why the Gemini prompt threshold matters. With 250,000 input tokens and 20,000 output tokens, Gemini 3.1 Pro uses its above-200,000-token rates:
(250,000 ÷ 1,000,000 × $4.00) + (20,000 ÷ 1,000,000 × $18.00) = $1.36
For GPT-5, the same usage is:
(250,000 ÷ 1,000,000 × $1.25) + (20,000 ÷ 1,000,000 × $10.00) = $0.5125
These examples show why entering realistic token counts matters. A model's advertised price per million input tokens is only one part of the final request cost. Your input-to-output token mix and, for Gemini 3.1 Pro, prompt size can change the result.
Quick Reference
| Model | Input Rate | Output Rate | Pricing Condition |
|---|---|---|---|
| Gemini 3.1 Pro | $2.00 / 1M tokens | $12.00 / 1M tokens | Prompt up to 200,000 tokens |
| Gemini 3.1 Pro | $4.00 / 1M tokens | $18.00 / 1M tokens | Prompt above 200,000 tokens |
| GPT-5 | $1.25 / 1M tokens | $10.00 / 1M tokens | Standard API pricing |
Why Use This Gemini 3.1 Pro API vs GPT-5 API per token cost Calculator & How Our Calculator Beats the Competition
The practical value of this calculator is that it puts the token counts and pricing formulas in one place. Different methods can still be useful depending on the size and complexity of the workload.
| Method | Ease of Use | Calculation Speed | Best For | Limitations |
|---|---|---|---|---|
| Toolhox Calculator | Enter token counts and requests | Immediate calculator result | Quick two-model cost estimates | Uses the pricing scope built into this tool and does not replace provider billing data |
| Manual Calculation | Requires applying each rate yourself | Depends on the person calculating | Checking a simple calculation | Easy to miss a threshold or input/output rate |
| Spreadsheet | Requires setup | Fast after formulas are created | Repeated scenario analysis | Requires maintaining formulas and pricing inputs |
| Provider Pricing Pages | Requires reading pricing tables | Not a calculator by themselves | Checking current official rates | Usually requires separate calculations for a specific workload |
Assumptions and Limitations
This calculator is an estimate based on the standard token rates researched for Gemini 3.1 Pro Preview and GPT-5. It assumes the entered input and output token counts represent the usage being compared. It does not attempt to reproduce a provider's invoice or every possible billing adjustment.
The calculator does not include every possible API cost category. For example, it does not calculate separate charges for optional services, special processing tiers, tool calls, grounding, storage, or other usage-based features. It also does not model cached-token pricing because the requested comparison is based on standard input and output token usage.
Gemini 3.1 Pro has an important prompt-size threshold. The calculator applies the higher Gemini rates when the entered input token count is above 200,000 tokens. If an application has a more complex pricing structure than the standard rates covered here, the result may not match the final provider charge.
Token counts can also differ between models because different tokenizers may divide the same text into different numbers of tokens. Therefore, entering the same token count for both models is a controlled cost comparison, not necessarily a prediction of the exact tokens either model will consume for the same application workload.
Pricing can change. Use the calculator as a budgeting and comparison aid, then confirm the applicable provider pricing before committing to a production deployment or large API purchase. The calculator does not provide a guarantee of future pricing or a provider invoice.
Do not enter sensitive information into the tool simply to estimate token costs. The calculator only needs numerical token counts and a request count; its supplied tool context does not establish a specific privacy, storage, or server-processing guarantee.
