Claude Sonnet 5.5 vs Gemini 3.8 Flash
At 6,000 chat requests per month (1,500 in / 400 out), Gemini 3.8 Flash costs $15.75 and Claude Sonnet 5.5 costs $42 — roughly 2.7× the spend.
| Spec | Claude Sonnet 5.5 | Gemini 3.8 Flash |
|---|---|---|
| Vendor | Anthropic | |
| Input / 1M tokens | $2 | $0.750 |
| Output / 1M tokens | $10 | $3.75 |
| Cached input / 1M | $0.100 | $0.075 |
| Context window | 1M tokens | 1.0M tokens |
| Max output | 128K tokens | 65.5K tokens |
| Input modalities | text, image | text, image, audio, video |
| Released | — | — |
| Cost per 1M cached reads | $0.100 | $0.075 |
Published list prices, last verified Oct 15, 2026. Source links are on each model's page.
Cost at three workloads
| Workload | Claude Sonnet 5.5 | Gemini 3.8 Flash | Difference |
|---|---|---|---|
| Customer-support reply (1,500 in / 400 out) | $0.0070 | $0.0026 | Gemini 3.8 Flash cheaper by $0.0044 |
| Document summary (20,000 in / 1,000 out) | $0.050 | $0.019 | Gemini 3.8 Flash cheaper by $0.031 |
| Code review pass (8,000 in / 1,500 out) | $0.031 | $0.012 | Gemini 3.8 Flash cheaper by $0.019 |
Which one fits your workload
- Long context: Gemini 3.8 Flash accepts more — 1.0M versus 1M tokens. If your retrieved context regularly exceeds 1M, only one of these will hold it.
- Long answers: Gemini 3.8 Flash has the lower output price ($3.75 vs $10 per million), which matters most when answers are long.
- High-volume, short answers: Gemini 3.8 Flash is cheaper on input ($0.750 vs $2 per million).
- Caching: at least one of these vendors publishes a discounted cached-input rate; if you resend the same system prompt and context, model the cache-hit rate or you will overestimate cost.
This comparison uses published price and specification data only. It does not rank output quality — run your own evaluation on your own prompts before switching a production default.