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Gemini 3.8 Flash vs GPT-5.6
Of the 5 public leaderboards that rate both, Gemini 3.8 Flash scores higher on 1 and GPT-5.6 on 4. On the ArtificialWatch Index, which takes the median of each model's percentile across the boards that score it, Gemini 3.8 Flash is at 50 and GPT-5.6 at 70.2 (out of 100).
Scores as published by each board; table composed September 28, 2026.
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Leaderboard by leaderboard
| Board | Gemini 3.8 Flash | GPT-5.6 | Higher |
|---|---|---|---|
| LMArena Elo (community votes) | 1,580 | 1,617.4 | GPT-5.6 |
| LiveBench global average (0-100) | 75.8 | 81.1 | GPT-5.6 |
| SimpleBench AVG@5 % (private set) | 82.4 | 71.7 | Gemini 3.8 Flash |
| Vals AI Vals Index accuracy % · weighted finance + coding tasks | 62.3 | 63.7 | GPT-5.6 |
| Artificial Analysis intelligence index · measured runs only | 40.9 | 47 | GPT-5.6 |
Raw scores are each board's own scale, so compare within a row, not across rows. Full table: the bench index.
For coding
On the ArtificialWatch coding index, Gemini 3.8 Flash is at 50 (#15 of 31) and GPT-5.6 at 65.5 (#10). Gemini 3.8 Flash scores higher on 1 of the 3 coding boards that rate both and GPT-5.6 on 2.
| Coding board | Gemini 3.8 Flash | GPT-5.6 |
|---|---|---|
| LMArena · Coding | 1,532.1 | 1,530.7 |
| LiveBench · Coding | 63.4 | 70.1 |
| Vals Vibe Code Bench | 78.7 | 80.5 |
Gemini 3.8 Flash at a glance
- Developer
- Status
- Live since September 2, 2026
- API price
- $0.75 input / $3.75 output per 1M tokens · Google, gemini-3.8-flash
- Context window
- 1.05M tokens
Live — GA Sep 2 · $0.75/$3.75 per 1M introductory through Dec 31, identical to 3.7 · 1M in / 64K out · 'our most intelligent Flash model' · 20 days after 3.7.
Gemini 3.8 Flash is GA — same price as 3.7, twenty days later
2026-09-02 · Google released Gemini 3.8 Flash today. The Gemini API changelog for September 2 reads: "Gemini 3.8 Flash generally available (GA): Released gemini-3.8-flash, our most intelligent Flash model, engineered for long-horizon software engineering, autonomous agents, and complex enterprise workflows."
GPT-5.6 at a glance
- Developer
- OpenAI
- Status
- Live since July 9, 2026
- API price
- $4 input / $20 output per 1M tokens · OpenAI, gpt-5.6
- Context window
- 1.05M tokens
Live — Sol · Terra · Luna since Jul 9 · repriced Jul 30: Luna −80%, Terra −20%.
Three ChatGPT leaks in five hours were one release note — and the line none of them quoted is the real change
2026-08-06 · Three separate leaks landed in five hours claiming three separate ChatGPT changes: an upgraded GPT-5.6 Sol for Plus and Pro, a new reasoning slider rolling out, and unlimited chats coming for free users. All three are real.
OpenAI cut Luna 80% — Azure kept the old price, so Luna costs 5× more on Azure than direct
2026-08-04 · OpenAI cut GPT-5.6 Luna by 80% on July 30. We covered it. What we did not check — and should have, because it is the number that actually lands on a bill — is whether the clouds passed it on.
Gemini 3.8 Flash vs GPT-5.6: quick answers
Which is better, Gemini 3.8 Flash or GPT-5.6?
It depends on what you measure. Of the 5 public leaderboards that rate both, Gemini 3.8 Flash scores higher on 1 and GPT-5.6 on 4. Gemini 3.8 Flash's widest lead is on SimpleBench; GPT-5.6's widest lead is on LiveBench. On the ArtificialWatch Index, which takes the median of each model's percentile across the boards that score it, Gemini 3.8 Flash is at 50 and GPT-5.6 at 70.2 (out of 100).
Which is newer, Gemini 3.8 Flash or GPT-5.6?
Gemini 3.8 Flash. It went live on September 2, 2026, 55 days after GPT-5.6 (July 9, 2026).
Which is cheaper, Gemini 3.8 Flash or GPT-5.6?
Gemini 3.8 Flash is cheaper on both input and output. On each vendor's own API, Gemini 3.8 Flash is $0.75 input / $3.75 output per million tokens and GPT-5.6 is $4 input / $20 output per million tokens. GPT-5.6's rate rises for prompts over 272K tokens. Prices as published in the models.dev catalog, as of 2026-09-27.
Which has the bigger context window, Gemini 3.8 Flash or GPT-5.6?
GPT-5.6, at 1.05M tokens against Gemini 3.8 Flash's 1.05M, as each vendor lists it.
How do Gemini 3.8 Flash and GPT-5.6 compare for coding?
On the ArtificialWatch coding index, Gemini 3.8 Flash is at 50 (#15 of 31) and GPT-5.6 at 65.5 (#10). Gemini 3.8 Flash scores higher on 1 of the 3 coding boards that rate both and GPT-5.6 on 2.
Who makes Gemini 3.8 Flash and GPT-5.6?
Gemini 3.8 Flash is from Google; GPT-5.6 is from OpenAI.
Where do these numbers come from?
Each score is the leaderboard's own published figure, read by ArtificialWatch (table composed September 28, 2026). Boards measure different things, so raw scores are only comparable within a row.
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Also: the bench index · API pricing · the wire