Claude Sonnet 5 vs Gemini 3.5 Flash: pricing and benchmarks
Gemini 3.5 Flash is 25% cheaper on input tokens ($1.50 vs $2.00 per 1M). Gemini 3.5 Flash is 10% cheaper on output tokens ($9.00 vs $10.00 per 1M). On our document Q&A workload (50,000 questions a month), Gemini 3.5 Flash costs $870.00 a month versus $1,100 for Claude Sonnet 5, 21% less. Roughly tied. Claude Sonnet 5 scores 156.2 and Gemini 3.5 Flash scores 154.7 on the Epoch Capabilities Index, and their confidence intervals overlap.
Prices verified September 14, 2026.
Which should you choose?
Roughly tied. Claude Sonnet 5 scores 156.2 and Gemini 3.5 Flash scores 154.7 on the Epoch Capabilities Index, and their confidence intervals overlap.
Claude Sonnet 5 scores 53.8% on DeepSWE vs 37.4% for Gemini 3.5 Flash.
Claude Sonnet 5 scores 65.6% on FrontierMath (Tiers 1–3) vs 62.8% for Gemini 3.5 Flash.
Gemini 3.5 Flash costs $3.375 per 1M tokens (3:1 input-to-output mix) vs $4.00 for Claude Sonnet 5, 16% less.
Gemini 3.5 Flash delivers statistically similar overall capability for 16% less.
Pricing and specs
| Claude Sonnet 5 | Gemini 3.5 Flash | |
|---|---|---|
| Provider | Anthropic | |
| API model ID | claude-sonnet-5 | gemini-3.5-flash |
| Input / 1M tokens | $2.00 | $1.50 |
| Cached input / 1M tokens | $0.20 | $0.15 |
| Output / 1M tokens | $10.00 | $9.00 |
| Long-context rates | — | — |
| Context window | 1M tokens | 1.05M tokens |
| Max output | 128K tokens | 66K tokens |
| Batch discount | 50% off | 50% off |
Benchmarks
| Claude Sonnet 5 | Gemini 3.5 Flash | |
|---|---|---|
| Epoch Capabilities Index | 156.2 | 154.7 |
| GPQA Diamond· Science reasoning | 87.4% | 90.4% |
| FrontierMath (Tiers 1–3)· Advanced math | 65.6% | 62.8% |
| SimpleQA Verified· Factual accuracy | 33.7% | 66.2% |
| ARC-AGI-2· Abstract reasoning | — | 72.1% |
| DeepSWE· Coding | 53.8% | 37.4% |
| APEX-Agents· Agentic work | 32.5% | — |
Source: Epoch AI, best recorded result per model (CC BY 4.0). A dash means no published score. See all benchmarks
Monthly cost for real workloads
| Workload | Claude Sonnet 5 | Gemini 3.5 Flash | Difference |
|---|---|---|---|
Support chatbot 100,000 replies a month, ~1,500 input tokens (system prompt + history) and ~400 output tokens each. | $700.00 | $585.00 | Gemini 3.5 Flash 16% cheaper |
Document Q&A (RAG) 50,000 questions a month with ~8,000 tokens of retrieved context and ~600 output tokens each. | $1,100 | $870.00 | Gemini 3.5 Flash 21% cheaper |
Coding agent 10,000 agent steps a month, ~40,000 input tokens each (70% read from the prompt cache) and ~2,000 output tokens. | $496.00 | $402.00 | Gemini 3.5 Flash 19% cheaper |
Estimates use standard list prices and ignore cache-write surcharges. Different tokenizers can count the same text differently, so test with your own prompts.
Claude Sonnet 5 vs Gemini 3.5 Flash cost calculator
- $870.00/mo$0.02 / request
- Claude Sonnet 5Anthropic$1,100/mo$0.02 / request
Standard-tier list prices. Long-context rates apply automatically where the provider publishes a threshold. Excludes cache-write surcharges, taxes, batch and volume discounts.
Claude Sonnet 5 pricing notes
Anthropic’s best combination of speed and intelligence.
- The $2 / $10 launch price is now the standard price; the planned rise to $3 / $15 will not happen.
- Cache writes cost $2.50 (5-minute cache) or $4 (1-hour cache) per 1M tokens.
- Uses Anthropic’s newer tokenizer, which produces roughly 30% more tokens for the same text.
Gemini 3.5 Flash pricing notes
Google’s Gemini 3.5 Flash model, with thinking, tool use and a 1M-token context window.
- Output price includes thinking tokens.
- Context cache storage costs $1.00 per 1M tokens per hour.
- Priority inference costs 1.8x the standard rate.
Frequently asked questions
- Is Claude Sonnet 5 cheaper than Gemini 3.5 Flash?
- Gemini 3.5 Flash is 25% cheaper on input tokens ($1.50 vs $2.00 per 1M). Gemini 3.5 Flash is 10% cheaper on output tokens ($9.00 vs $10.00 per 1M). On our document Q&A workload (50,000 questions a month), Gemini 3.5 Flash costs $870.00 a month versus $1,100 for Claude Sonnet 5, 21% less.
- Which is more capable, Claude Sonnet 5 or Gemini 3.5 Flash?
- Roughly tied. Claude Sonnet 5 scores 156.2 and Gemini 3.5 Flash scores 154.7 on the Epoch Capabilities Index, and their confidence intervals overlap.
- How much does Claude Sonnet 5 cost per 1M tokens?
- Claude Sonnet 5 costs $2.00 per 1M input tokens and $10.00 per 1M output tokens, and $0.20 per 1M cached input tokens on Anthropic’s standard tier.
- How much does Gemini 3.5 Flash cost per 1M tokens?
- Gemini 3.5 Flash costs $1.50 per 1M input tokens and $9.00 per 1M output tokens, and $0.15 per 1M cached input tokens on Google’s standard tier.
- Which has the larger context window, Claude Sonnet 5 or Gemini 3.5 Flash?
- Gemini 3.5 Flash has the larger context window: 1.05M tokens versus 1M for Claude Sonnet 5.