Claude 3.5 Sonnet

Claude 3.5 Sonnet is a large language model created by Anthropic, released June 20, 2024. It was later followed by Claude Sonnet 3.6 in October, which was originally called “Claude 3.5 Sonnet (new)” or “the upgraded Claude 3.5 Sonnet”.

Sonnet 3.5 was deprecated on August 13, 2025 and retired on October 28, 2025.

Details

• Launched alongside Artifacts in the Claude.ai interface.
• Same 200K context as Claude 3, with max output raised to 8,192 tokens.
• Priced identically to Claude 3 Sonnet ($3 / $15 per million tokens) while substantially outperforming Claude 3 Opus on Anthropic’s reported benchmarks.
• The October 22, 2024 “upgraded Claude 3.5 Sonnet” — colloquially Sonnet 3.6 — shipped under the same family but a new snapshot.

Further reading

• “On Claude 3.5 Sonnet” - Zvi Mowshowitz (Jun 24, 2024)

Last updated July 5, 2026

Claude 3.5 Sonnet is online via Amazon Bedrock. It will be shutdown on July 30, 2026.¹

Anthropic

Claude 3.5 Sonnet was retired from the Anthropic API after 495 days in deployment.²

Timeline

• 2024-06-20: Active
• 2025-10-22: Legacy (Sonnet 3.6 launch)
• 2025-08-13: Deprecated
• 2025-10-28: Retired

Post-deployment report

No post-deployment report exists on record as of July 5, 2026.

External links

• OpenRouter

Training

Pre-training data was collected up to April 2024, compared to Claude 3’s cutoff of August 2023.

Evaluations

Sonnet 3.5 scored highest in the Situational Awareness Dataset (SAD) benchmark, relative to Instant 1.2, Claude 2.1, Claude 3, several GPT-4 snapshots, among other models.¹

• “Won’t vs. Can’t: Sandbagging-like Behavior from Claude models” (Witten et al, Feb 12, 2025)

This page gathers model outputs that have been shared online.

Artwork

Interactions with other models

Sonnet 3.5’s assessment of Claude 3 Opus (source)