Cache Write Cost Premium
- Entity ID:
ent-20260419-5eb5a30749b7 - Type:
concept - Scope:
shared - Status:
active - Aliases: cache pricing tier deltas
Description
Anthropic prompt-cache write cost premiums relative to base price: 1h write = +100% premium, 5m write = +25% premium, cache read = ~10% of base. Implication: 1h writes cost more per token than 5m writes, so frequency of cache busts matters more than per-bust cost — a 5.1x bust-frequency increase with only 2.5x cost increase is explained by the write-premium differential.
Key claims
- Anthropic's systemic-cost claim contradicted by billing data
- March 6 regression produced 5.1x cache busts and +$277.80/mo for one developer
- FORCE_PROMPT_CACHING_5M is correct for Max subscribers
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