Is Claude Fable 5.1 more expensive than Claude Fable 5?

No. Both models charge identical base rates of $10 per million input tokens and $50 per million output tokens. The only pricing change in 5.1 is a 75% cut to cache-read costs, dropping from $1 to $0.25 per million tokens, which only matters if you use prompt caching.

Which model is cheaper for a typical output-heavy workload?

Neither — at 100M input and 30M output tokens, both models cost exactly $2,500 per month since their input and output rates are identical. The only scenario where 5.1 pulls ahead financially is when cached input reads make up a large share of usage.

Are Claude Fable 5 and 5.1 both still available?

Yes, both remain active and callable via API as of October 2026. Fable 5.1 is the current default, while Fable 5 continues to serve requests as a legacy option at the same base pricing.

What context window do these models support?

Both Claude Fable 5 and Fable 5.1 support a 1M-token context window with a 128K-token maximum output, based on publicly available documentation. Confirm current limits with your provider before building context-dependent applications, as these figures can shift between releases.

HEAD-TO-HEAD · FLAGSHIP-TIER · VERIFIED OCTOBER 19, 2026

Claude Fable 5 vs Fable 5.1 — is the newer version actually cheaper?

Claude Fable 5 and Claude Fable 5.1 share identical headline pricing: $10 per million input tokens and $50 per million output tokens. On base API rates alone, there is no cost difference between them — the real story is elsewhere in the rate card.

Spec	Claude Fable 5	Claude Fable 5.1
Input / 1M tokens	$10.00	$10.00
Output / 1M tokens	$50.00	$50.00
Context window	1M	1M

The output price gap

There is no output pricing gap between these two models — both charge exactly $50 per million output tokens, a hefty 5x premium over input pricing that makes output-heavy workloads (long-form generation, detailed agentic responses, extensive reasoning traces) the dominant cost driver for either model. Teams optimizing spend should focus on trimming output length and reasoning effort rather than choosing between these two versions on price alone.

Context window

Both models ship with a 1M-token context window and a 128K maximum output limit, so there is no context-window trade-off to weigh here either — this is based on publicly available specs and should be confirmed against current provider documentation before architecting around it, as context limits can vary slightly by API provider.

Worked example

At 100M input tokens and 30M output tokens in a month, the math is identical for both models: input cost is 100 x $10 = $1,000, and output cost is 30 x $50 = $1,500, for a combined monthly total of $2,500 for Claude Fable 5 and $2,500 for Claude Fable 5.1. Since base rates are tied, the deciding factor for real-world spend becomes secondary pricing like cache reads, where Fable 5.1 is substantially cheaper.

Prices from the LLM Price Watch daily tracker, 2026-10-19. Prices change; use the calculator with your own usage for an exact comparison, or see the full price table for every tracked model.