Gemini 4 Carbon vs Gemini 3.8 Flash
Gemini 3.8 Flash is 2.7x cheaper than Gemini 4 Carbon on our example workload, at list prices.
Side by side
| Measure | Gemini 4 Carbon | Gemini 3.8 Flash |
|---|---|---|
| Provider | ||
| Input / 1M tokens | $2.00 current (through November 30, 2026; $4.00 from December 1, 2026) | $0.750 current (through December 31, 2026; $1.50 from January 1, 2027) |
| Output / 1M tokens | $10.00 current (through November 30, 2026; $20.00 from December 1, 2026) | $3.75 current (through December 31, 2026; $7.50 from January 1, 2027) |
| Output price ÷ input price | 5.0x | 5.0x |
| Blended / 1M (3:1) | $4.00 | $1.50 |
| Context window | 1M | 1M |
| ≈ English words that fit | 750,000 | 750,000 |
| 1,000 calls (2000+500 tok) | $9.00 | $3.38 |
| AA Intelligence Index | 60 | 31 |
| LMArena Text | 1526 (high, preliminary) | 1497 (high) |
| Blended $ per AA index point | $0.067 | $0.048 |
List prices from official pages (Google, Google), verified 2026-11-11. Benchmarks from public leaderboards (Artificial Analysis, LMArena), not run by us. Word counts use the rough 0.75 words per token rule for English. "$ per index point" is our own arithmetic (blended price ÷ index score), a rough value-for-money signal, not a benchmark.
What real workloads cost
Four example request shapes, priced at list rates with no caching or batch discounts. Monthly figures assume 100,000 requests.
| Workload | Gemini 4 Carbon | Gemini 3.8 Flash | Gap |
|---|---|---|---|
| Support chat reply a short system prompt, recent chat history and a reply | $0.00900 each $900.00 / mo | $0.00337 each $337.50 / mo | 2.7x |
| RAG answer a question plus about 20K tokens of retrieved documents, and a cited answer | $0.0480 each $4,800.00 / mo | $0.0180 each $1,800.00 / mo | 2.7x |
| 10-step agent task an agent loop of 10 model calls, each re-reading about 8K tokens of context and emitting a 400-token tool call | $0.2000 each $20,000.00 / mo | $0.0750 each $7,500.00 / mo | 2.7x |
| Long-report summary one 200K-token document summarized into about 2K tokens | $0.4200 each $42,000.00 / mo | $0.1575 each $15,750.00 / mo | 2.7x |
When to pick each
- Pick Gemini 3.8 Flash when cost is the main constraint: at list prices it is 2.7x cheaper than Gemini 4 Carbon on a typical 2,000-in / 500-out call ($3.38 vs $9.00 per 1,000 calls).
- Pick Gemini 4 Carbon when answer quality matters more than price: it scores 60 vs 31 on the Artificial Analysis Intelligence Index, and costs 2.7x more per call.
- Both come from Google, so switching between them is usually a one-line model-name change on the same API and SDK; many teams route easy calls to the cheaper one and hard calls to the other.
Context and pricing limits
- Gemini 4 Carbon: 1M tokens of context. Gemini 3.8 Flash: 1M. Same size.
- Gemini 4 Carbon: Standard list price $2/$10 through Nov 30, 2026; $4/$20 from Dec 1, 2026. The prices above are this tier; check the official pricing page before committing.
- Gemini 3.8 Flash: Promo price through Dec 31, 2026; $1.50/$7.50 from Jan 1, 2027. The prices above are this tier; check the official pricing page before committing.
- Cached input, batch and off-peak discounts can cut real bills a lot and differ by provider; they are not included here.
FAQ
Is Gemini 3.8 Flash cheaper than Gemini 4 Carbon?
Yes, on our 2000-in / 500-out example call it costs $0.00337 vs $0.00900, 2.7x less.
Which has the larger context window?
Neither: both accept 1M tokens.
Which scores higher on benchmarks?
Gemini 4 Carbon scores 60 vs 31 on the Artificial Analysis Intelligence Index. On LMArena Text, Gemini 4 Carbon is 1526 (high, preliminary) and Gemini 3.8 Flash is 1497 (high). Benchmarks are averages; test both on your own prompts.
Run your own numbers in the token cost estimator · Gemini 4 Carbon pricing · Gemini 3.8 Flash pricing · All comparisons