o3 vs Step 3.5 Flash
| Spec | o3 | Step 3.5 Flash |
|---|---|---|
| Respan Index | 26.1 (#97) | 26.5 (#95) |
| Blended price per 1M | $3.5 | $0.15 |
| Context window | 200K | 256K |
| Input / output per 1M | $2 / $8 | $0.1 / $0.3 |
| Max output | 100K | - |
| Input | text, vision | text |
| Released | 2025-04-16 | 2026-02-12 |
Respan Index by category
Each category is scored 0 to 100, and how far ahead the winner is. Leads under a point are close to even.
| Category | o3 | Step 3.5 Flash |
|---|---|---|
| Coding | 8.0 o3 | 10.7 Step 3.5 Flash |
| Agents | 8.6 o3 | 23.9 Step 3.5 Flash |
| Reasoning | 38.9 o3 | 34.6 Step 3.5 Flash |
| Knowledge & language | 49.3 o3 | 24.8* Step 3.5 Flash |
| Human preference | 48.6 o3 | 44.6 Step 3.5 Flash |
* Estimated: no published scores in that category. How the Respan Index works
Benchmarks both report
Step 3.5 Flash leads on 2 of the 3 benchmarks both report. Higher is better. Each score links to where it was published.
FAQ
Is o3 better than Step 3.5 Flash?
Step 3.5 Flash scores 26.5 on the Respan Index (#95), ahead of o3 at 26.1 (#97). Step 3.5 Flash leads on 2 of the 3 benchmarks both report.
Which is cheaper, o3 or Step 3.5 Flash?
o3 lists at $2 input and $8 output per 1M tokens; Step 3.5 Flash at $0.1 and $0.3. Step 3.5 Flash is 23x cheaper per token at list price.
Which has the larger context window?
o3 accepts 200K tokens and Step 3.5 Flash 256K tokens.