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API price comparison · Updated

Gemini 3.8 Flash vs GPT-6.1 Terra pricing

Quick answer

Gemini 3.8 Flash costs $0.75 per million input tokens and $3.75 per million output tokens; GPT-6.1 Terra costs $1.00 and $5.00. For an agent task (80,000 input tokens, 60,000 of them cached, and 6,000 output), Gemini 3.8 Flash costs $0.042 and GPT-6.1 Terra $0.053: Gemini 3.8 Flash costs 21% less. Gemini 3.8 Flash's price changes on Jan 1, 2027 to $1.50 input and $7.50 output per million tokens.

Compare your monthly cost on Gemini 3.8 Flash and GPT-6.1 Terra

Estimated monthly cost
Gemini 3.8 Flash$413$0.0041 per request
GPT-6.1 Terra$550$0.0055 per request

Gemini 3.8 Flash costs 25% less for this workload. Excludes cache writes, tools and taxes.

Gemini 3.8 Flash vs GPT-6.1 Terra prices per million tokens

PriceGemini 3.8 FlashGPT-6.1 Terra
Model IDgemini-3.8-flashgpt-6.1-terra
Input$0.75$1.00
Cache read$0.075$0.05
Cache writeStorage billed per hour$1.25
Output$3.75$5.00
Batch in / out$0.375 / $1.875$0.50 / $2.50
Long promptsSame rateOver 272,000: $2.00 / $7.50
Scheduled changeFrom Jan 1, 2027: $1.50 / $7.50None announced
StatusAvailableAvailable

Prices for each provider’s own API, from Google Gemini’s pricing page and OpenAI’s pricing page. The lower price in each row is highlighted. Ganivra uses these same rates to price Gemini 3.8 Flash and GPT-6.1 Terra calls.

What one request costs on Gemini 3.8 Flash and GPT-6.1 Terra

Worked out from the prices above at standard rates, with no Batch discount. Long-prompt rates apply where a model has them.

RequestGemini 3.8 FlashGPT-6.1 TerraPer 1,000 requestsDifference
Chat reply3,000 input tokens, 500 output$0.0041$0.0055$4.13 / $5.50Gemini 3.8 Flash costs 25% less
Document summary30,000 input tokens, 1,500 output$0.028$0.037$28.13 / $37.50Gemini 3.8 Flash costs 25% less
Agent task80,000 input tokens (60,000 cached), 6,000 output$0.042$0.053$42.00 / $53.00Gemini 3.8 Flash costs 21% less
Long document300,000 input tokens, 2,000 output$0.233$0.615$233 / $615GPT-6.1 Terra costs 2.6× as much

What changes which one costs less

Prompt caching
Cache reads cost $0.075 per million, 10% of the input price on Gemini 3.8 Flash, and $0.05 per million, 5% of the input price on GPT-6.1 Terra. The more of each prompt you reuse, the more this decides the bill.
Cache writes
Gemini 3.8 Flash charges no write fee; Gemini bills cache storage per million tokens per hour. GPT-6.1 Terra charges $1.25 per million tokens written to cache.
Long prompts
On Gemini 3.8 Flash, one rate at any prompt length. On GPT-6.1 Terra, prompts over 272,000 tokens cost $2.00 input and $7.50 output for the whole request. A 300 prompt costs $0.233 on Gemini 3.8 Flash and $0.615 on GPT-6.1 Terra.
Batch API
Gemini 3.8 Flash costs 50% less through the Batch API: $0.375 input and $1.875 output. GPT-6.1 Terra costs 50% less through the Batch API: $0.50 input and $2.50 output.
Price change on Jan 1, 2027
Gemini 3.8 Flash goes from $0.75 input and $3.75 output to $1.50 input and $7.50 output per million tokens. Calls before then keep the old price; the agent task goes from $0.042 to $0.084.
Token counts
Google Gemini and OpenAI use different tokenizers, so the same text becomes a different number of tokens. The model with the lower per-token price can still cost more per request; compare on your own prompts before switching.

Compare them on your own customers, not a sample request.

Ganivra prices every Gemini 3.8 Flash and GPT-6.1 Terra call you make and adds it up by customer, feature and workflow, next to what each customer pays. Switch a workflow and see what it did to each customer’s margin.

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Gemini 3.8 Flash vs GPT-6.1 Terra pricing questions

Is Gemini 3.8 Flash cheaper than GPT-6.1 Terra?

Per million tokens, Gemini 3.8 Flash costs $0.75 input and $3.75 output, and GPT-6.1 Terra $1.00 input and $5.00 output. For an agent task (80,000 input tokens, 60,000 of them cached, and 6,000 output), Gemini 3.8 Flash costs 21% less: $42.00 against $53.00 per 1,000 tasks.

How much does Gemini 3.8 Flash cost per million tokens?

$0.75 input and $3.75 output per million tokens on Google Gemini's API, with cached input at $0.075 and Batch at $0.375 input and $1.875 output. The rate is the same at any prompt length.

How much does GPT-6.1 Terra cost per million tokens?

$1.00 input and $5.00 output per million tokens on OpenAI's API, with cached input at $0.05 and Batch at $0.50 input and $2.50 output. Prompts over 272,000 tokens cost $2.00 input and $7.50 output.

Which is cheaper for long prompts, Gemini 3.8 Flash or GPT-6.1 Terra?

For a 300,000 input tokens, 2,000 output request, Gemini 3.8 Flash costs $0.233 and GPT-6.1 Terra $0.615: GPT-6.1 Terra costs 2.6× as much. On Gemini 3.8 Flash, one rate at any prompt length; on GPT-6.1 Terra, prompts over 272,000 tokens cost $2.00 input and $7.50 output for the whole request.

Is Gemini 3.8 Flash getting more expensive?

Yes. On Jan 1, 2027, Gemini 3.8 Flash goes from $0.75 input and $3.75 output to $1.50 input and $7.50 output per million tokens. After the change, the agent task costs $0.084 on Gemini 3.8 Flash against $0.053 on GPT-6.1 Terra.

How do I compare Gemini 3.8 Flash and GPT-6.1 Terra on my own traffic?

Record what each call actually used, then price the same usage on both models. Ganivra does this from your recorded calls: it shows what each customer, feature and workflow would cost on Gemini 3.8 Flash and on GPT-6.1 Terra, next to what each customer pays you.

Every model on one page: Gemini 3.8 Flash pricing · GPT-6.1 Terra pricing · all model price comparisons · all supported models.