Claude Sonnet 4.5 API Pricing
Anthropic · context window 1M · prices updated 2026-09-15
Where Claude Sonnet 4.5 sits on price
At $15.00 per million output tokens, Claude Sonnet 4.5 is a premium tier model — 7.2× the median output price of $2.08, which puts it cheaper than 13% and pricier than 87% of the models we track. It sits 14th cheapest of the 27 Anthropic models we track. Output costs 5.0× input, the usual spread — trim both, starting with the answer length.
Cached input is 90% cheaper. On an input-heavy workload you need roughly a 28% cache-hit rate to take 25% off the input line — reachable for chatbots and agents that resend the same system prompt and history.
What real workloads cost on Claude Sonnet 4.5
These three workloads are the ones teams actually run on a premium-priced model — a $15.00/1M model is not bought for the same job as one ten times the price.
| Workload | Per request | Per month |
|---|---|---|
| Support chatbot — 500 conversations/day (5K in / 1.4K out) Conversation history re-sent each turn — the classic prompt-caching win. | $0.036 | $540 |
| Coding agent — 300 sessions/day (60K in / 12K out) Multi-step loops re-read the same files; caching matters more than raw price. | $0.36 | $3240 |
| Long-context analysis — 200 runs/day (250K in / 4K out) Only possible on large-context models; input cost is nearly the whole bill. | $0.81 | $4860 |
Model your exact traffic in the API cost calculator — it preloads Claude Sonnet 4.5 with caching and batch options.
Claude Sonnet 4.5 price history
Claude Sonnet 4.5's price has not moved since we began tracking it on Aug 2, 2026 — 44 days of stability in a market where 78 of the 334 models we track have repriced over the same period. Anthropic's lineup has held steady across the board.
Change-points from our daily price snapshots (tracking since Aug 2, 2026; intraday moves between snapshots are not captured).
Claude Sonnet 4.5 vs Kimi K3 (batch)
The closest-priced alternative from another vendor is Kimi K3 (batch) (Moonshot (Kimi)) — priced within a rounding error on output, with identical input pricing. When two models land this close on price, the decision is quality on your own workload, not the price sheet: run 50 real requests through both and compare.
See Kimi K3 (batch) pricing →Cheaper alternatives
More Anthropic models
Frequently asked questions
› How much does the Claude Sonnet 4.5 API cost?
Claude Sonnet 4.5 costs $3.00 per million input tokens and $15.00 per million output tokens, with cached input at $0.3 per million (90% cheaper). That works out to roughly 66,667 output tokens per dollar.
› What does the support chatbot workload cost on Claude Sonnet 4.5?
Support chatbot — 500 conversations/day (5K in / 1.4K out) costs about $0.036 per request and $540 per month on Claude Sonnet 4.5. Conversation history re-sent each turn — the classic prompt-caching win.
› What does it cost to fill Claude Sonnet 4.5's 1M context window?
Sending 1M of input in a single request costs $3.00 at $3.00 per million tokens — before any output. With prompt caching that same fill drops to about $0.3 on repeat requests. This is why large context windows are cheap to advertise and expensive to actually use.
› Is Claude Sonnet 4.5 worth the price?
Claude Sonnet 4.5 sits in the middle of the market (14 of 27 by price within Anthropic). The honest test is a routing experiment: send the same 200 real requests to this model and to a tier below, and compare failure rate against the price gap — most teams find a majority of traffic never needed the pricier model.