Claude Fable 5 vs Gemini 3.1 Flash-Lite
Anthropic's Claude Fable 5 and Google's Gemini 3.1 Flash-Lite both target production language workloads, but they price and behave differently. Here is the side-by-side.
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The short answer
Gemini 3.1 Flash-Lite is the cheaper option — roughly 35.6x less on a blended workload, and it suits ultra-cheap high-volume tasks. Claude Fable 5 justifies its premium when you need long-horizon agentic engineering. Only Claude Fable 5 does native reasoning, which matters for multi-step tasks but adds billable thinking tokens.
Anthropic • Claude 5
$10.00 / $50.00
/ 1M tokens (input / output)
Anthropic's most capable widely released model, built for agents that run for hours rather than seconds. Adaptive thinking is always on and cannot be disabled, which is part of why it tops the Artificial Analysis Intelligence Index — and why its cost per task runs roughly triple GPT-5.6 Sol's for a one-point intelligence lead.
Google • Gemini 3.1
$0.25 / $1.50
/ 1M tokens (input / output)
Google's efficiency tier and a long-term stable target, priced for workloads measured in millions of calls rather than thousands. It gives up the deeper reasoning of 3.5 Flash, so it suits mechanical tasks — classification, extraction, moderation — where a million tokens of context still helps but chain-of-thought does not.
Input price
Gemini 3.1 Flash-Lite is 98% cheaper than Claude Fable 5 on input tokens.
Output price
Gemini 3.1 Flash-Lite is 97% cheaper than Claude Fable 5 on output tokens — usually the side that dominates the bill.
Monthly cost at three workload sizes
Standard (non-batch, non-cached) rates. Reasoning models will exceed these figures because thinking tokens bill as output.
| Workload | Claude Fable 5 | Gemini 3.1 Flash-Lite | Difference |
|---|---|---|---|
| Light — 1M in / 200K out | $20 | $1 | $19 |
| Moderate — 10M in / 2M out | $200 | $6 | $195 |
| Heavy — 100M in / 20M out | $2,000 | $55 | $1,945 |
Specification comparison
| Attribute | Claude Fable 5 | Gemini 3.1 Flash-Lite |
|---|---|---|
| Input (/ 1M tokens) | $10.00 | $0.25 |
| Output (/ 1M tokens) | $50.00 | $1.50 |
| Cached input | $1.00 | — |
| Context window | 1,000,000 tokens | 1,048,576 tokens |
| Max output | 128,000 tokens | 65,536 tokens |
| Native reasoning | Yes | No |
| Knowledge cutoff | 2026-01 | 2025-01 |
| Relative latency | high | low |
| Open weights | No | No |
| API model ID | claude-fable-5 | gemini-3.1-flash-lite |
| Status | stable | stable |
Claude Fable 5: 5-minute cache writes $12.50/MTok, 1-hour $20/MTok. Requires 30-day data retention, so not available under zero-data-retention terms.
Choose Claude Fable 5 if…
- Multi-hour autonomous coding runs
- Large codebase migrations
- Hard scientific workflows
- High-stakes legal and medical analysis
Choose Gemini 3.1 Flash-Lite if…
- Content moderation at volume
- Classification and routing
- Lightweight summarization
- Cheap long-context retrieval
Frequently asked
Is Claude Fable 5 or Gemini 3.1 Flash-Lite cheaper?
Gemini 3.1 Flash-Lite is cheaper. On a blended 3:1 input-to-output workload it costs about 35.6x less than Claude Fable 5.
Which has the larger context window, Claude Fable 5 or Gemini 3.1 Flash-Lite?
Gemini 3.1 Flash-Lite has the larger window at 1.05M tokens versus 1M.
Should I use Claude Fable 5 or Gemini 3.1 Flash-Lite?
Pick Claude Fable 5 for long-horizon agentic engineering. Pick Gemini 3.1 Flash-Lite for ultra-cheap high-volume tasks. If cost dominates the decision, Gemini 3.1 Flash-Lite wins; if you need the capability ceiling, benchmark both on your own evals before committing.