Claude Fable 5.1 vs Gemini 3.8 Flash: pricing and benchmarks
Gemini 3.8 Flash is 93% cheaper on input tokens ($0.75 vs $10.00 per 1M). Gemini 3.8 Flash is 93% cheaper on output tokens ($3.75 vs $50.00 per 1M). On our document Q&A workload (50,000 questions a month), Gemini 3.8 Flash costs $412.50 a month versus $5,500 for Claude Fable 5.1, 93% less. Roughly tied. Claude Fable 5.1 scores 164.5 and Gemini 3.8 Flash scores 156.5 on the Epoch Capabilities Index, and their confidence intervals overlap.
Prices verified September 14, 2026.
Which should you choose?
Roughly tied. Claude Fable 5.1 scores 164.5 and Gemini 3.8 Flash scores 156.5 on the Epoch Capabilities Index, and their confidence intervals overlap.
Claude Fable 5.1 scores 90.2% on FrontierMath (Tiers 1–3) vs 68.4% for Gemini 3.8 Flash.
Gemini 3.8 Flash costs $1.50 per 1M tokens (3:1 input-to-output mix) vs $20.00 for Claude Fable 5.1, 93% less.
Gemini 3.8 Flash delivers statistically similar overall capability for 93% less.
Pricing and specs
| Claude Fable 5.1 | Gemini 3.8 Flash | |
|---|---|---|
| Provider | Anthropic | |
| API model ID | claude-fable-5-1 | gemini-3.8-flash |
| Input / 1M tokens | $10.00 | $0.75 |
| Cached input / 1M tokens | $0.25 | $0.075 |
| Output / 1M tokens | $50.00 | $3.75 |
| Long-context rates | — | — |
| Context window | 1M tokens | 1.05M tokens |
| Max output | 128K tokens | 66K tokens |
| Batch discount | 50% off | 50% off |
Benchmarks
| Claude Fable 5.1 | Gemini 3.8 Flash | |
|---|---|---|
| Epoch Capabilities Index | 164.5 | 156.5 |
| GPQA Diamond· Science reasoning | — | 93.9% |
| FrontierMath (Tiers 1–3)· Advanced math | 90.2% | 68.4% |
| SimpleQA Verified· Factual accuracy | 70.8% | 69.7% |
| ARC-AGI-2· Abstract reasoning | 90.0% | — |
| DeepSWE· Coding | — | 73.8% |
| APEX-Agents· Agentic work | 47.4% | — |
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 Fable 5.1 | Gemini 3.8 Flash | Difference |
|---|---|---|---|
Support chatbot 100,000 replies a month, ~1,500 input tokens (system prompt + history) and ~400 output tokens each. | $3,500 | $262.50 | Gemini 3.8 Flash 93% cheaper |
Document Q&A (RAG) 50,000 questions a month with ~8,000 tokens of retrieved context and ~600 output tokens each. | $5,500 | $412.50 | Gemini 3.8 Flash 93% 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. | $2,270 | $186.00 | Gemini 3.8 Flash 92% 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 Fable 5.1 vs Gemini 3.8 Flash cost calculator
- $412.50/mo$0.0083 / request
- Claude Fable 5.1Anthropic$5,500/mo$0.11 / 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 Fable 5.1 pricing notes
Anthropic’s model for demanding reasoning and long-horizon agentic work.
- Cache hits cost 2.5% of the base input price, versus 10% on other Claude models.
- Cache writes cost $12.50 (5-minute cache) or $20 (1-hour cache) per 1M tokens.
- Uses Anthropic’s newer tokenizer, which produces roughly 30% more tokens for the same text.
- US-only inference (inference_geo: "us") costs 1.1x.
Gemini 3.8 Flash pricing notes
Google’s newest Flash model, with thinking, tool use and a 1M-token context window.
- Introductory price through December 31, 2026. From January 1, 2027: $1.50 input, $0.15 cached, $7.50 output per 1M tokens.
- Output price includes thinking tokens.
- Priority inference costs 1.8x the standard rate.
Frequently asked questions
- Is Claude Fable 5.1 cheaper than Gemini 3.8 Flash?
- Gemini 3.8 Flash is 93% cheaper on input tokens ($0.75 vs $10.00 per 1M). Gemini 3.8 Flash is 93% cheaper on output tokens ($3.75 vs $50.00 per 1M). On our document Q&A workload (50,000 questions a month), Gemini 3.8 Flash costs $412.50 a month versus $5,500 for Claude Fable 5.1, 93% less.
- Which is more capable, Claude Fable 5.1 or Gemini 3.8 Flash?
- Roughly tied. Claude Fable 5.1 scores 164.5 and Gemini 3.8 Flash scores 156.5 on the Epoch Capabilities Index, and their confidence intervals overlap.
- How much does Claude Fable 5.1 cost per 1M tokens?
- Claude Fable 5.1 costs $10.00 per 1M input tokens and $50.00 per 1M output tokens, and $0.25 per 1M cached input tokens on Anthropic’s standard tier.
- How much does Gemini 3.8 Flash cost per 1M tokens?
- Gemini 3.8 Flash costs $0.75 per 1M input tokens and $3.75 per 1M output tokens, and $0.075 per 1M cached input tokens on Google’s standard tier.
- Which has the larger context window, Claude Fable 5.1 or Gemini 3.8 Flash?
- Gemini 3.8 Flash has the larger context window: 1.05M tokens versus 1M for Claude Fable 5.1.