Comparison
Gemini 4 vs Gemini 3.1 Pro
One of these models exists. Comparing them is therefore an exercise in reading leaked specifications against documented ones — useful for planning, useless as a buying decision. Every unconfirmed cell below carries its label.
| Attribute | Gemini 3.1 Pro documented | Gemini 4 claimed | Confidence |
|---|---|---|---|
| Status | Shipping since 19 Feb 2026 | Unreleased | CONF |
| Max output tokens | 64k | 256k | LEAK |
| Context window | 1M tokens, with a price premium above 200k | Multi-million, no figure leaked | RUM |
| Reasoning control | Thinking budget parameter | Selectable high-effort compute mode | LEAK |
| Standard input price | $2.00 / 1M tokens | Unknown | CONF |
| Standard output price | $12.00 / 1M tokens | Unknown | CONF |
| Structured visual output | SVG generation with mixed reliability | SVG, 3D modelling, interactive simulation | LEAK |
| Published benchmarks | Full model card and evaluation table | None | CONF |
The output ceiling is the real story
Context windows get the marketing, but output limits are what bite in practice. A model that can read a million tokens and write only 64,000 of them cannot emit a large refactor, a full test suite or a long structured document in one pass — it has to be orchestrated across calls, and every hand-off is a place for state to be lost.
If the leaked 256k figure holds, that constraint loosens by roughly 4×. For agentic coding workloads that is a more meaningful change than any plausible context increase, and it is also the change with the clearest cost implication, since output tokens bill at six times input.
Why a bigger context window matters less than it sounds
Gemini 3.1 Pro already reads a million tokens, and pricing steps up above 200,000 — $4.00 input and $18.00 output per million beyond that threshold, against $2.00 and $12.00 below it. Extending the maximum does not remove that cliff. For most workloads the binding constraint is what you can afford to send, not what the model can accept.
The Flash line complicates the comparison
Gemini 3.8 Flash shipped on 2 September 2026 — seven months newer than the Pro flagship — and Google described it as its "most intelligent workhorse model yet, built for long-horizon coding and autonomous agents". For a growing share of work the practical choice today is not Pro versus a future Pro, but Pro versus a much cheaper and much newer Flash.
That is also the strongest context for the 7-month Pro pause: Google has had a credible answer for most workloads while the frontier tier stayed quiet.
What to do now
- Ship on 3.1 Pro. It is documented, priced and stable; Gemini 4 is a rumour with two missed windows behind it.
- Evaluate 3.8 Flash honestly. On agentic and long-horizon work it may already beat the older Pro model at a fraction of the cost.
- Keep the model ID in config. Migration should be a config change, not a refactor.
- Instrument output tokens. If a 256k ceiling arrives, that is where your bill will move.
- Watch the API changelog, not the headlines. The model ID appearing there is the only launch signal that means anything.
Frequently asked questions
Should I wait for Gemini 4 or build on Gemini 3.1 Pro now?
Build now. Gemini 4 has no release date, has missed two reported windows, and could be renamed or shelved. Gemini 3.1 Pro is documented, priced and stable. If you keep your model ID in configuration rather than hard-coded, migrating later is a one-line change.
What is the biggest difference Gemini 4 would bring?
On the leaked specs, the 256k output ceiling — roughly 4× the current limit. Output length, not context length, is what currently constrains long-horizon code generation and agentic work, so that is the change most likely to alter what you can build.
Is Gemini 3.8 Flash better than Gemini 3.1 Pro?
They sit on different tiers and Google positions Flash as its workhorse rather than its frontier model. Gemini 3.8 Flash is seven months newer and Google describes it as its "most intelligent workhorse model yet, built for long-horizon coding and autonomous agents", so for many agentic workloads it is a serious candidate — which is part of why the Pro line has been able to stand still for 7 months.
Will Gemini 3.1 Pro be deprecated when Gemini 4 launches?
Not immediately. Google has kept previous Pro generations available well past a successor’s launch, with deprecation notices published in the API changelog ahead of any shutdown. Watch the changelog rather than the announcement post.