Claude Sonnet 5.5 vs Gemini 3.8 Flash
There is no quality verdict yet: the AIGROW small-business benchmark has not run Claude Sonnet 5.5. On price, Gemini 3.8 Flash costs less: $0.75 in and $3.75 out per million tokens, against $2 in and $10 out for Claude Sonnet 5.5.
US dollars, standard rate, shortest context band. Price only: the benchmark has not run both.
- Claude Sonnet 5.5
- $10.00
- Gemini 3.8 Flash
- $3.75
- Claude Sonnet 5.5, per M tokens
- $2 / $10
- Gemini 3.8 Flash, per M tokens
- $0.75 / $3.75
3,000 tokens in and 400 out each, at list price.
Anthropic's new workhorse against Google's, where Flash stays cheaper even after its 2027 price rise. 1,000 support replies cost $10.00 on Claude Sonnet 5.5 and $3.75 on Gemini 3.8 Flash, so Claude Sonnet 5.5 costs 2.7 times as much. Claude Sonnet 5.5 was released on 28 Sep 2026, Gemini 3.8 Flash was released on 2 Sep 2026.
What each one costs
The API price per million tokens and the cheapest app plan with each model, from the makers’ own pages. Each name opens that model’s full price page.
- Claude Sonnet 5.5
- On the Anthropic API, Claude Sonnet 5.5 costs $2 per million input tokens and $10 per million output tokens. In Claude, it comes with the free plan, and the cheapest paid plan with it is Pro at $20/mo. Plan prices read 20 October 2026. AIGROW API credit runs Claude Sonnet 5.5 at $1.50 / $7.50 per million input / output tokens, 25% below list price. See API credit
- Gemini 3.8 Flash
- On the Google API, Gemini 3.8 Flash costs $0.75 per million input tokens and $3.75 per million output tokens.
Side by side
Each maker’s published rate for its standard tier. Cached input is what a repeated prompt prefix costs once the provider has stored it.
| Fact | Claude Sonnet 5.5 | Gemini 3.8 Flash |
|---|---|---|
| Maker | Anthropic | |
| Tier | Workhorses | Workhorses |
| Input, per M tokens | $2.00 | $0.75 |
| Output, per M tokens | $10.00 | $3.75 |
| Cached input | $0.10 | $0.075 |
| Context window | 1M | 1.05M |
| Released | 28 Sep 2026 | 2 Sep 2026 |
| Weights | Closed weights | Closed weights |
What a job costs on each
1,000 runs of each job at the two list prices. The gap moves from job to job because the models price input, output and cached context differently.
| Job | Claude Sonnet 5.5 | Gemini 3.8 Flash | Cheaper |
|---|---|---|---|
| Support reply3,000 in, 400 out. | $10.00 | $3.75 | Gemini 3.8 Flash, 63% less |
| Document summary25,000 in, 1,000 out. | $60.00 | $22.50 | Gemini 3.8 Flash, 63% less |
| Agent task80,000 in (70,000 cached), 3,000 out. | $57.00 | $24.00 | Gemini 3.8 Flash, 58% less |
The token counts are ours, chosen to look like real work; the prices are the makers’. A model with no published cache price bills the agent task’s repeated context at its full input rate.
The small print
What each base rate leaves out, from the makers’ own pages: surcharges, discounts, promotions and cache pricing.
- Claude Sonnet 5.5
- Cache read is 0.05x input on this model ($0.10). Cache write $2.50 (5 min) or $4 (1 h). Batch API 50% off. US-only inference bills 1.1x. Full context window billed at standard rates. Max output 128K. Anthropic’s pricing page
- Gemini 3.8 Flash
- Launch price through 2026-12-31; from 2027-01-01 it becomes $1.50 / $7.50, cached $0.15. Batch and Flex 50% off; Priority $1.35 / $6.75. Cache storage $0.50 per MTok per hour (rising to $1.00). Google’s pricing page
Other comparisons
Every head to head on the list that involves Claude Sonnet 5.5 or Gemini 3.8 Flash.
Run Claude Sonnet 5.5 up to 25% below list price
AIGROW API credit covers Claude Sonnet 5.5 at published rates never above the list prices here, and $25 buys $100 of credit.
Prices checked 15 October 2026