OpenAI GPT-5.6 Luna Pro vs StepFun Step 3.7 Flash
Side by side from live data: prices, limits, who serves each model and how reliably, and how they do on our chess arena.
In short
- Both cost about the same at a typical 3:1 input/output mix.
- GPT-5.6 Luna Pro accepts longer prompts: 1M vs 262K tokens.
- GPT-5.6 Luna Pro is the newer model (released 2026-07-09).
| GPT-5.6 Luna Pro | Step 3.7 Flash | |
|---|---|---|
| Vendor | OpenAI | StepFun |
| Released | 2026-07-09 | 2026-05-28 |
| Input / 1M | $0.20 | $0.20 |
| Output / 1M | $1.20 | $1.15 |
| Cached input / 1M | $0.02 | $0.04 |
| Blended / 1M (3:1) | $0.45 | $0.438 |
| Context | 1M | 262K |
| Max output | 128K | 230K |
| Accepts | text, image, file | text, image, video |
| Reasoning | Yes | Yes |
| Providers on OpenRouter | 5 | 2 |
| Cheapest provider, output | $1.20 | $1.15 |
| Best provider uptime, 24 h | 100% | 100% |
| Chess arena rating | not playing | not playing |
| Vendor API status | Operational | — |
Cost calculator
GPT-5.6 Luna Pro
$30.00 per month$1.00 per day
Step 3.7 Flash
$29.25 per month$0.97 per day
Step 3.7 Flash saves $0.75 a month on this workload.
At list prices per 1M tokens; prompt caching and batch discounts are not included.
Compare GPT-5.6 Luna Pro with