ModelRefs / Claude Sonnet 4.5 vs Claude Sonnet 4
Claude Sonnet 4.5 vs Claude Sonnet 4
Claude Sonnet 4.5 vs Claude Sonnet 4: side-by-side benchmarks, pricing, context windows, coding ability and deployment. Pick the right model for your stack.
Overview
Claude Sonnet 4: Claude Sonnet 4 is Anthropic's May 2025 hybrid-reasoning model for coding, visual reasoning, tool use, and agent workflows. The dated claude-sonnet-4-20250514 snapshot was retired on Anthropic-operated platforms on June 15, 2026 and is retained as a historical evaluation and migration reference.
Claude Sonnet 4.5: Claude Sonnet 4.5 is Anthropic's balanced frontier model, designed for complex reasoning, coding, and agentic tasks while maintaining production-grade speed. It builds on the Claude 4 family's emphasis on honesty and reduced hallucination rates.
Context window: Claude Sonnet 4 accepts up to 200,000 tokens, Claude Sonnet 4.5 up to 200,000. Confirm the limit for your specific deployment channel before relying on it.
Claude Sonnet 4 vs Claude Sonnet 4.5 at a glance
| Attribute | Claude Sonnet 4 | Claude Sonnet 4.5 |
|---|---|---|
| Provider | Anthropic | Anthropic |
| Released | 2025-05-22 | 2025-09-29 |
| Context window | 200,000 tokens | 200,000 tokens |
| Input price | $3/M tokens | $3/M tokens |
| Output price | $15/M tokens | $15/M tokens |
| Licence | Proprietary | Proprietary |
| Self-hostable | No, hosted only | No, hosted only |
| Modalities | text, vision | text, vision |
Benchmarks reported for both
| Benchmark | Claude Sonnet 4 | Claude Sonnet 4.5 | Reported |
|---|---|---|---|
| SWE-Bench Verified (resolved) | 72.7 | 77.2 | 2025-05-22 / 2025-09-29 |
Each row compares the same benchmark, the same reported metric, and the same task set. Scores are as published by their cited sources on the dates shown. Different runs still use different harnesses and prompts, so treat these as directional evidence rather than a head-to-head result.
Where they differ most
- Coding: Claude Sonnet 4 57%, Claude Sonnet 4.5 77%. Claude Sonnet 4.5 leads on this dimension.
- Agentic: Claude Sonnet 4 61%, Claude Sonnet 4.5 66%. Claude Sonnet 4.5 leads on this dimension.
- Cost Efficiency: Claude Sonnet 4 37%, Claude Sonnet 4.5 37%. Both score the same on this dimension.
Capability scores are ModelRefs' own derived signals, not vendor claims or benchmark results. Validate against your own workload before relying on them.
Continue your research
Use these connected ModelRefs sections to compare alternatives, inspect implementation paths, and review the evidence and governance boundaries relevant to Claude Sonnet 4.5 vs Claude Sonnet 4.
Frequently asked questions
Which is better, Claude Sonnet 4.5 or Claude Sonnet 4?
Claude Sonnet 4.5 and Claude Sonnet 4 target different workloads — see the benchmark and pricing tables for a side-by-side answer.
Is Claude Sonnet 4.5 cheaper than Claude Sonnet 4?
Compare $0.00300 vs $0.00300 on this page.