# Gemma 4 31B-it FP8 vs GPT-5.6 Luna

On provider list prices, Gemma 4 31B-it FP8 costs $0.39 per million input tokens against $0.20 for GPT-5.6 Luna: effectively level. Output is $0.97 against $1.20 (1.2x).

## Specifications

| | Gemma 4 31B-it FP8 | GPT-5.6 Luna |
| --- | --- | --- |
| Lab | Google | OpenAI |
| Access | Open weights | API only |
| Context window | 256K tokens | 1M tokens |
| List price, input | $0.39 / M tokens | $0.20 / M tokens |
| List price, output | $0.97 / M tokens | $1.20 / M tokens |
| Cached input | n/a | $0.02 / M tokens |
| License | Apache 2.0 | Proprietary API |
| Fine-tunable | Yes | No |

Specifications and provider list prices from the Allocate catalog, checked 2026-07-21.

## What the numbers say

Take 1,000,000 requests a month at 1,200 input and 350 output tokens each. That workload costs $660 a month on GPT-5.6 Luna and $807.50 on Gemma 4 31B-it FP8 at list: a gap of $147.50, or 1.2x.

GPT-5.6 Luna reads 1M tokens per request against 256K for Gemma 4 31B-it FP8, 3.8x the window. That decides which one can take whole documents without splitting them.

## Choose Gemma 4 31B-it FP8 for

- Open weights you can fine-tune and own
- Fine-tuning under a permissive license (Apache 2.0)

## Choose GPT-5.6 Luna for

- The lower list price ($0.20 in / $1.20 out per M tokens)
- The longer context window (1M vs 256K tokens)
- Published cached-input pricing ($0.02 per M tokens)

## Common questions

### Which is cheaper, Gemma 4 31B-it FP8 or GPT-5.6 Luna?

GPT-5.6 Luna, on this workload shape. At list prices it is $0.20/$1.20 per million tokens in and out against $0.39/$0.97 for Gemma 4 31B-it FP8. Billed on Allocate: $0.21/$1.28 against $0.42/$1.04.

### Which has the bigger context window?

GPT-5.6 Luna: 1,000,000 tokens (1M) against 262,144 (256K) for Gemma 4 31B-it FP8.

### Can I fine-tune Gemma 4 31B-it FP8 or GPT-5.6 Luna?

Gemma 4 31B-it FP8 publishes open weights (Apache 2.0) and can be fine-tuned on your own data. GPT-5.6 Luna is a closed model served over API; its weights are not available.

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[HTML page](https://allocate.network/compare/google-gemma-4-31b-it-vs-openai-gpt-5-6-luna) · [Gemma 4 31B-it FP8](https://allocate.network/models/google-gemma-4-31b-it.md) · [GPT-5.6 Luna](https://allocate.network/models/openai-gpt-5-6-luna.md) · [Machine-readable catalog](https://allocate.network/catalog.json)