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API price comparison · Updated

Gemini 3.5 Flash-Lite vs GPT-6 Luna pricing

Quick answer

Gemini 3.5 Flash-Lite costs $0.30 per million input tokens and $2.50 per million output tokens; GPT-6 Luna costs $0.10 and $0.50. For an agent task (80,000 input tokens, 60,000 of them cached, and 6,000 output), Gemini 3.5 Flash-Lite costs $0.023 and GPT-6 Luna $0.0056: Gemini 3.5 Flash-Lite costs 4.1× as much.

Compare your monthly cost on Gemini 3.5 Flash-Lite and GPT-6 Luna

Estimated monthly cost
Gemini 3.5 Flash-Lite$215$0.0022 per request
GPT-6 Luna$55.00$0.0006 per request

GPT-6 Luna costs 74% less for this workload. Excludes cache writes, tools and taxes.

Gemini 3.5 Flash-Lite vs GPT-6 Luna prices per million tokens

PriceGemini 3.5 Flash-LiteGPT-6 Luna
Model IDgemini-3.5-flash-litegpt-6-luna
Input$0.30$0.10
Cache read$0.03$0.01
Cache writeStorage billed per hour$0.125
Output$2.50$0.50
Batch in / out$0.15 / $1.25$0.05 / $0.25
Long promptsSame rateOver 272,000: $0.20 / $0.75
Scheduled changeNone announcedNone 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 3.5 Flash-Lite and GPT-6 Luna calls.

What one request costs on Gemini 3.5 Flash-Lite and GPT-6 Luna

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

RequestGemini 3.5 Flash-LiteGPT-6 LunaPer 1,000 requestsDifference
Chat reply3,000 input tokens, 500 output$0.0022$0.0006$2.15 / $0.550Gemini 3.5 Flash-Lite costs 3.9× as much
Document summary30,000 input tokens, 1,500 output$0.013$0.0037$12.75 / $3.75Gemini 3.5 Flash-Lite costs 3.4× as much
Agent task80,000 input tokens (60,000 cached), 6,000 output$0.023$0.0056$22.80 / $5.60Gemini 3.5 Flash-Lite costs 4.1× as much
Long document300,000 input tokens, 2,000 output$0.095$0.061$95.00 / $61.50GPT-6 Luna costs 35% less

What changes which one costs less

Prompt caching
Cache reads cost $0.03 per million, 10% of the input price on Gemini 3.5 Flash-Lite, and $0.01 per million, 10% of the input price on GPT-6 Luna. The more of each prompt you reuse, the more this decides the bill.
Cache writes
Gemini 3.5 Flash-Lite charges no write fee; Gemini bills cache storage per million tokens per hour. GPT-6 Luna charges $0.125 per million tokens written to cache.
Long prompts
On Gemini 3.5 Flash-Lite, one rate at any prompt length. On GPT-6 Luna, prompts over 272,000 tokens cost $0.20 input and $0.75 output for the whole request. A 300 prompt costs $0.095 on Gemini 3.5 Flash-Lite and $0.061 on GPT-6 Luna.
Batch API
Gemini 3.5 Flash-Lite costs 50% less through the Batch API: $0.15 input and $1.25 output. GPT-6 Luna costs 50% less through the Batch API: $0.05 input and $0.25 output.
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 3.5 Flash-Lite and GPT-6 Luna 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 3.5 Flash-Lite vs GPT-6 Luna pricing questions

Is Gemini 3.5 Flash-Lite cheaper than GPT-6 Luna?

Per million tokens, Gemini 3.5 Flash-Lite costs $0.30 input and $2.50 output, and GPT-6 Luna $0.10 input and $0.50 output. For an agent task (80,000 input tokens, 60,000 of them cached, and 6,000 output), Gemini 3.5 Flash-Lite costs 4.1× as much: $22.80 against $5.60 per 1,000 tasks.

How much does Gemini 3.5 Flash-Lite cost per million tokens?

$0.30 input and $2.50 output per million tokens on Google Gemini's API, with cached input at $0.03 and Batch at $0.15 input and $1.25 output. The rate is the same at any prompt length.

How much does GPT-6 Luna cost per million tokens?

$0.10 input and $0.50 output per million tokens on OpenAI's API, with cached input at $0.01 and Batch at $0.05 input and $0.25 output. Prompts over 272,000 tokens cost $0.20 input and $0.75 output.

Which is cheaper for long prompts, Gemini 3.5 Flash-Lite or GPT-6 Luna?

For a 300,000 input tokens, 2,000 output request, Gemini 3.5 Flash-Lite costs $0.095 and GPT-6 Luna $0.061: GPT-6 Luna costs 35% less. On Gemini 3.5 Flash-Lite, one rate at any prompt length; on GPT-6 Luna, prompts over 272,000 tokens cost $0.20 input and $0.75 output for the whole request.

How do I compare Gemini 3.5 Flash-Lite and GPT-6 Luna 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 3.5 Flash-Lite and on GPT-6 Luna, next to what each customer pays you.

Every model on one page: Gemini 3.5 Flash-Lite pricing · GPT-6 Luna pricing · all model price comparisons · all supported models.