Claude Fable 5 vs Claude Sonnet 5
Anthropic's Claude Fable 5 and Anthropic's Claude Sonnet 5 both target production language workloads, but they price and behave differently. Here is the side-by-side.
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The short answer
Claude Sonnet 5 is the cheaper option — roughly 5.0x less on a blended workload, and it suits fast claude-quality reasoning at scale. Claude Fable 5 justifies its premium when you need long-horizon agentic engineering.
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.
Anthropic • Claude 5
$2.00 / $10.00
/ 1M tokens (input / output)
The workhorse Claude tier: a full million tokens of context and adaptive thinking at $2/$10, which undercuts the previous Sonnet 4.6 generation by a third on input while raising the context ceiling fivefold. The default pick for latency-sensitive products that still want Claude's writing and tool-use behaviour.
Input price
Claude Sonnet 5 is 80% cheaper than Claude Fable 5 on input tokens.
Output price
Claude Sonnet 5 is 80% 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 | Claude Sonnet 5 | Difference |
|---|---|---|---|
| Light — 1M in / 200K out | $20 | $4 | $16 |
| Moderate — 10M in / 2M out | $200 | $40 | $160 |
| Heavy — 100M in / 20M out | $2,000 | $400 | $1,600 |
Specification comparison
| Attribute | Claude Fable 5 | Claude Sonnet 5 |
|---|---|---|
| Input (/ 1M tokens) | $10.00 | $2.00 |
| Output (/ 1M tokens) | $50.00 | $10.00 |
| Cached input | $1.00 | $0.20 |
| Context window | 1,000,000 tokens | 1,000,000 tokens |
| Max output | 128,000 tokens | 128,000 tokens |
| Native reasoning | Yes | Yes |
| Knowledge cutoff | 2026-01 | 2026-01 |
| Relative latency | high | low |
| Open weights | No | No |
| API model ID | claude-fable-5 | claude-sonnet-5 |
| 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 Claude Sonnet 5 if…
- Production chat and copilots
- Long-document analysis
- Tool-heavy agents needing fast turns
- Code review and PR automation
Frequently asked
Is Claude Fable 5 or Claude Sonnet 5 cheaper?
Claude Sonnet 5 is cheaper. On a blended 3:1 input-to-output workload it costs about 5.0x less than Claude Fable 5.
Which has the larger context window, Claude Fable 5 or Claude Sonnet 5?
Both accept up to 1M tokens, so context is not a differentiator here.
Should I use Claude Fable 5 or Claude Sonnet 5?
Pick Claude Fable 5 for long-horizon agentic engineering. Pick Claude Sonnet 5 for fast claude-quality reasoning at scale. If cost dominates the decision, Claude Sonnet 5 wins; if you need the capability ceiling, benchmark both on your own evals before committing.