ANTHROPIC MODEL GUIDE
Claude Sonnet 4.5 API
The moving Claude Sonnet 4.5 alias for balanced coding, analysis, and production agents.
Choosing and integrating
Claude Sonnet 4.5 API pricing breakdown
Claude Sonnet 4.5 (claude-sonnet-4-5) is billed by token usage. Prices below are USD per 1M tokens. LLMFly AI rates already include the 0.5x group multiplier; do not apply it again. Provider reference prices are separate. These rates come from the site's Model Plaza snapshot; confirm live catalog and account rates before calling.
Example: a request with 10,000 uncached input tokens and 1,000 output tokens costs approximately $0.0225 in LLMFly AI token charges. This excludes cache writes, tools, retries, and other additional fees.
- Platform and provider prices use their own input-token tiers. Do not apply provider long-context multipliers to platform prices.
- Not listed does not mean free. Account for cache reads, cache writes, and uncached input in their respective billing categories.
- Token cost = tokens in each billing category × its price per million ÷ 1,000,000. Add tools and other charges separately.
| Price source | Input tokens per request | Input | Output | Cache write | Cache read | 1h cache write |
|---|---|---|---|---|---|---|
| LLMFly AI | 0 < tokens ≤ 200,000 | $1.5 | $7.5 | $1.875 | $0.15 | $3 |
| LLMFly AI | 200,000 < tokens | $3 | $11.25 | $3.75 | $0.3 | $6 |
| Provider reference | 0 < tokens ≤ 200,000 | $3 | $15 | $3.75 | $0.3 | $6 |
| Provider reference | 200,000 < tokens | $6 | $22.5 | $7.5 | $0.6 | $12 |
Pricing tiers and additional charges
Claude cache writes, cache reads, long-context tiers, and tool charges vary by exact model. The calculator uses only rates listed in Model Plaza and never treats a missing charge as free.
Claude Sonnet 4.5 capabilities and workloads
The moving Claude Sonnet 4.5 alias for balanced coding, analysis, and production agents.
Balanced production coding and agent tasks that still target the 4.5 family.
- Tool use, structured output, and image understanding on supported interfaces.
- Designed for coding, document analysis, and multi-step agent workflows, with capability varying by tier.
Limits to check before migration
- Alias IDs and dated snapshot IDs have different upgrade behavior; use the exact ID shown on this page.
- Native beta headers, tools, and retention conditions do not automatically establish gateway support.
Comparing Claude Sonnet 4.5 with sibling models
Compare the exact API ID, vendor lifecycle, context, maximum output, tools, and thinking controls first. Then measure pass rate, latency, tokens, and total cost on the same tasks. The Claude Sonnet 4.5 version or tier label alone does not prove better results.
Use the exact model ID when connecting
Set the model field to claude-sonnet-4-5; do not infer its spelling from the display name. Configure the API address and key using the access documentation; the snippet only shows the model field, not a complete request.
- Send a minimal text request and inspect the response and usage.
- Test streaming, tool calls, and structured output separately if your application needs them.
- Check retry behavior and spending limits before increasing traffic.
{
"model": "claude-sonnet-4-5"
}Vendor capability versus gateway access
Claude Sonnet 4.5's specifications above were checked in vendor documentation. No paid inference requests or account-route modality, tool, or beta-parameter tests were run in this review. Validate your application before launch; documentation review is not end-to-end compatibility certification.
Frequently asked questions
What should I put in the model field?
Use the exact ID claude-sonnet-4-5, not the display name.
How is the discount calculated?
The current 0.5x multiplier is applied to the base rate, giving 50% off the catalog's official reference. Amounts are shown per million tokens.
Do these prices include every possible fee?
Not necessarily. Check cache-write duration, tools, and other route charges separately. Use the full pricing table and actual usage records to reconcile a bill.
What are the context and output limits?
Vendor documentation lists 200K context and 64K maximum output; confirm gateway route limits separately.
Use the Claude Sonnet 4.5 API
LLMFly AI provides this model. Use the exact ID claude-sonnet-4-5 and confirm current account pricing in Model Plaza.