Gemini 3.5 Flash vs Gemini 4 Carbon
Google · US | Google · US · Updated June 2026
Quick verdict
Both are Google models. Gemini 4 Carbon is the newer, generally stronger default; reach for Gemini 3.5 Flash when its lower price or a specific cost or latency profile matters more than the latest capabilities.
Gemini 3.5 Flash and Gemini 4 Carbon are both Google models, so the real question is not which lab to trust but which tier fits your workload and budget. Gemini 3.5 Flash is google's fast, cheap class that now beats last year's premium Pro — the value-and-reach play. Gemini 4 Carbon is google's October 28, 2026 limited release for cyber defenders - top of the Artificial Analysis index at launch, priced at $2/$10 introductory, with no public API date yet. Since both come from the same lab, the comparison below focuses on the tier-and-cost trade-offs that actually separate them.
Key differences at a glance
- ▸Price: Gemini 3.5 Flash is about 1.3× cheaper on input ($1.5/$9 per 1M tokens vs $2/$10 per 1M tokens) — modest, but it adds up at steady volume.
- ▸Context window: both advertise 1M (~1,500 pages). Tie on paper — test on your own long inputs, since usable recall varies by model.
- ▸Recency: Gemini 4 Carbon is the newer model by about 5 months (released October 28, 2026), usually meaning fresher training data and capabilities.
Side-by-side specs
| Spec | Gemini 3.5 Flash | Gemini 4 Carbon |
|---|---|---|
| Provider | Google (US) | Google (US) |
| Released | May 19, 2026 | October 28, 2026 |
| Context window | 1M (~1,500 pages) | 1M tokens (~1,500 pages) |
| Price (in/out) | $1.5/$9 per 1M tokens | $2/$10 per 1M tokens |
| Open weight? | No — API only | No — API only |
| Modalities | text, image, audio, video, code | text, image, audio, video, code |
| SWE-Bench Verified | Not published | Not published |
| MRCR v2 @ 1M | Not published | Not published |
Who wins what
Speed — roughly 4x faster than rivals
Gemini 3.5 Flash
Google's fast, cheap class that now beats last year's premium Pro — the value-and-reach play — and it runs cheaper at $1.5/$9 per 1M tokens.
Cost — about a third the price
Gemini 3.5 Flash
At $1.5/$9 per 1M tokens it undercuts Gemini 4 Carbon ($2/$10 per 1M tokens), and that gap compounds at volume.
Default in the Gemini app and Search AI Mode
Gemini 3.5 Flash
Gemini 3.5 Flash lists default in the Gemini app and Search AI Mode among its strengths; Gemini 4 Carbon does not.
Ranked first on the Artificial Analysis Intelligence Index v5.0 with 59 at launch (Artificial Analysis now shows 60)
Gemini 4 Carbon
Gemini 3.5 Flash is comparatively weak here — pro-tier 3.5 held back at launch
Google-reported 88.2% on SEC-bench Pro and 54.8% on ExploitGym for vulnerability discovery and exploit validation
Gemini 4 Carbon
Google's October 28, 2026 limited release for cyber defenders - top of the Artificial Analysis index at launch, priced at $2/$10 introductory, with no public API date yet — and it is the newer of the two.
Google-reported 71.0% on CWE-bench for patching
Gemini 4 Carbon
Gemini 4 Carbon lists google-reported 71.0% on CWE-bench for patching among its strengths; Gemini 3.5 Flash does not.
Lowest cost at scale
Gemini 3.5 Flash
At $1.5/$9 per 1M tokens, it is the cheaper of the two — the gap dominates the bill on high-volume workloads.
Which should you pick?
A cost-sensitive startup shipping high volume
→ Gemini 3.5 Flash
At $1.5/$9 per 1M tokens it undercuts Gemini 4 Carbon, and on millions of tokens that margin decides the monthly bill.
Anyone whose priority is speed — roughly 4x faster than rivals
→ Gemini 3.5 Flash
It is specifically built for that.
Anyone whose priority is ranked first on the artificial analysis intelligence index v5.0 with 59 at launch (artificial analysis now shows 60)
→ Gemini 4 Carbon
That is its strongest area.
Gemini 3.5 Flash: where it fits
Google's fast, cheap class that now beats last year's premium Pro — the value-and-reach play. Released May 19, 2026 by Google, it is built for speed — roughly 4x faster than rivals, cost — about a third the price, default in the Gemini app and Search AI Mode, and high-volume multimodal work.
Its trade-offs are real: flash tier, not the deepest reasoning, and pro-tier 3.5 held back at launch. At $1.5 in / $9 out per million tokens, it sits in the mid price band.
Gemini 4 Carbon: where it fits
Google's October 28, 2026 limited release for cyber defenders - top of the Artificial Analysis index at launch, priced at $2/$10 introductory, with no public API date yet. Released October 28, 2026 by Google, it is built for ranked first on the Artificial Analysis Intelligence Index v5.0 with 59 at launch (Artificial Analysis now shows 60), google-reported 88.2% on SEC-bench Pro and 54.8% on ExploitGym for vulnerability discovery and exploit validation, google-reported 71.0% on CWE-bench for patching, and introductory $2/$10 per million tokens, matching Gemini 4 Argon, with cached input 95% off.
Its trade-offs: limited release: rolling out to a subset of cyber defenders, then trusted partners via the Fairwind Program, with no date for developers or consumers, no public API model listing yet, so most users cannot call it today, introductory pricing rises to $4/$20 afterward, and Google has not said when that happens, and google has not published context or modality specs - the 1M window and modalities shown come from Artificial Analysis and Vals. At $2 in / $10 out per million tokens, it sits in the mid price band.
The bottom line for this matchup
Because Gemini 3.5 Flash and Gemini 4 Carbon come from the same lab (Google), they share the same training philosophy and ecosystem — the decision is purely tier vs. cost. Gemini 4 Carbon is the more capable, more recent option; the other earns its place only when its price or latency profile fits a specific job better. Most teams should default to Gemini 4 Carbon and drop down only with a concrete reason.
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See pricingFrequently asked questions
Is Gemini 3.5 Flash or Gemini 4 Carbon better for coding?
Public SWE-Bench figures are not available for either model, so the honest test is your own repository — run an identical real bug through both. By design, Gemini 3.5 Flash leans toward speed — roughly 4x faster than rivals while Gemini 4 Carbon leans toward ranked first on the artificial analysis intelligence index v5.0 with 59 at launch (artificial analysis now shows 60), and that positioning usually predicts which feels better on your codebase.
Which is cheaper, Gemini 3.5 Flash or Gemini 4 Carbon?
Gemini 3.5 Flash is cheaper — $1.5/$9 per 1M tokens vs $2/$10 per 1M tokens, roughly 1.3× apart on input.
Which has the bigger context window?
Both advertise 1M (~1,500 pages). Remember advertised ≠ usable: recall typically degrades before the ceiling.
Should I upgrade from Gemini 3.5 Flash to Gemini 4 Carbon?
Since both are Google models, the newer one (Gemini 4 Carbon) is usually the better default unless you need a specific cost or latency profile from the other.
Which is newer, Gemini 3.5 Flash or Gemini 4 Carbon?
Gemini 4 Carbon — released October 28, 2026, about 5 months after Gemini 3.5 Flash.
Related comparisons
Specifications and benchmarks reflect publicly reported figures as of June 2026 and may change as providers release updates. Always verify on your own workload.