Compare · updated 2026-11-01

GPT-6 Luna vs GPT-5.5

GPT-6 Luna is better at quick answers; GPT-5.5 is better at writing, coding, reasoning, maths, structured data, long documents, translation. GPT-6 Luna is the cheaper of the two on output.

Measured quality by task

Quality is Nivana’s measured score for each kind of task, from weekly pairwise evals judged by models from several labs. Prices are live AI Gateway list prices per million tokens. Updated 2026-11-01. How this is measured.

Price and context

Which should you use?

Use the one that wins the kind of work you do most, unless the price gap outweighs the quality gap for easy requests. Or don’t choose: Nivana scores both, and the rest of the pool, on every request and sends it to whichever is best for that request.

Questions

Is GPT-6 Luna better than GPT-5.5?

On Nivana’s weekly evals GPT-6 Luna scores higher on 1 of 8 task types (quick answers) and GPT-5.5 on 7 (writing, coding, reasoning, maths, structured data, long documents, translation). Neither is better at everything.

Which is better for coding, GPT-6 Luna or GPT-5.5?

GPT-5.5: 91/100 against 84/100 for GPT-6 Luna on Nivana’s coding evals.

Which is better for writing, GPT-6 Luna or GPT-5.5?

GPT-5.5: 94/100 against 90/100 for GPT-6 Luna on Nivana’s writing evals.

Which is cheaper, GPT-6 Luna or GPT-5.5?

GPT-6 Luna: $0.5 per million output tokens against $30 for GPT-5.5, about 60.0× less. A typical chat answer costs about $0.0005 on GPT-6 Luna and $0.029 on GPT-5.5.