Is Gemini 3.1 Flash-Lite or GPT-5.6 Luna cheaper?

GPT-5.6 Luna is cheaper on input — $0.20 per million against $0.25, a difference of 1.3x. Output rates differ separately, and a workload heavy on generated text can reverse which one costs less overall.

Which has the larger context window?

GPT-5.6 Luna, at 1,050,000 tokens against 1,000,000.

Can I compare them on my own prompt?

Yes. The calculator counts any text against every model at once, so you can see both figures for your actual workload rather than for a generic example.

Gemini 3.1 Flash-Lite vs GPT-5.6 Luna

The cheapest current model from each of Google and OpenAI, for high-volume work.

Side by side

Attribute	Gemini 3.1 Flash-Lite	GPT-5.6 Luna
Input, per 1M tokens	$0.25	$0.20
Output, per 1M tokens	$1.50	$1.20
Context window	1,000,000	1,050,000
Provider	Google	OpenAI
Tokenizer	Google tokenizer	o200k_base
Long-context tier	none	above 272,000
Retires	no date announced	no date announced

Which to choose

On cost, GPT-5.6 Luna is 1.3x cheaper per million input tokens. On a workload that reads far more than it writes, that ratio is close to the whole difference in the bill.
On capacity, GPT-5.6 Luna holds more in one request. That matters only if you are near the smaller ceiling — below it, the extra room changes nothing.
On long prompts, at least one of these bills the entire request at an elevated rate past a threshold. A comparison made on short prompts can invert once you cross it.

What this page does not tell you. Which model produces better answers. That depends on your task, and this site has no benchmark data — everything above is drawn from published pricing and specifications. Compare quality by running your own prompts through both.

Count your prompt on both Gemini 3.1 Flash-Lite details GPT-5.6 Luna details

Common questions

Is Gemini 3.1 Flash-Lite or GPT-5.6 Luna cheaper?: GPT-5.6 Luna is cheaper on input — $0.20 per million against $0.25, a difference of 1.3x. Output rates differ separately, and a workload heavy on generated text can reverse which one costs less overall.
Which has the larger context window?: GPT-5.6 Luna, at 1,050,000 tokens against 1,000,000.
Can I compare them on my own prompt?: Yes. The calculator counts any text against every model at once, so you can see both figures for your actual workload rather than for a generic example.