Cache reads on Fable 5.1 are a quarter of what they cost on Fable 5
Reading from a prompt cache costs 0.1 times the base input price on every Claude model except two[1]. On Claude Fable 5.1 and Claude Mythos 5.1 it is 0.025 times, which against a $10 input price works out to $0.25 per million tokens[1].
Claude Fable 5 charges $1 per million for the same read at the same $10 input price[1]. The read is a quarter of what it was, and nothing else about the price moved[1].
Cache writes did not change: 1.25 times the input price for a 5 minute cache and 2 times for a 1 hour one, which is $12.50 and $20 here[1]. On both models a 5 minute cache still pays for itself after one read[1]. The difference shows up after that. Sending a 1 million token prefix ten times costs $14.75 on Fable 5.1 and $21.50 on Fable 5, against $100 without caching[1].
The other Claude models stay at 0.1 times[1]. Per million tokens that is $0.50 on Opus 5, $0.20 on Sonnet 5 and $0.10 on Haiku 4.5[1].