The Open-Source AI Stack
RSS
All models

Models · claude

Claude Sonnet 4.6

Proprietary Anthropic · 2026-02-17 · Proprietary

Mid-tier Sonnet refresh shipped February 17 2026 at the same $3 / $15 pricing as Sonnet 4.5, with a 1M context window in beta. Default model for Free and Pro plans on Claude.ai at launch. Anthropic reported Claude Code users preferred Sonnet 4.6 over Sonnet 4.5 roughly 70 percent of the time.

Cost

$3.00 / Mtok input
$15.00 / Mtok output

Anthropic API · as of 2026-05-21

source ↗

Speed

49 tok/sec output
1153 ms TTFT

· as of 2026-05-21

source ↗

Architecture

tokens in Embedding vocab not disclosed × N layers Architecture not disclosed (proprietary or undocumented) Output projection tokens out
Schema-generated from data/models.yaml. Every label is auditable against the model's sources.

Specs

Architecture
unknown
Total params
not disclosed
Active params
not disclosed
Context window
1.0M tokens
Attention
unknown
Position encoding
unknown
Post-training
rlhf, constitutional
OSI-approved
no
Data released
no
Training code
not released

Benchmarks

Each score carries the date it was published; we never infer or interpolate missing scores.

General reasoning

GPQA-Diamond 79.9 as of 2026-05-21 source ↗

Code

SWE-Bench Verified 80.2 as of 2026-02-17 source ↗

Available quantizations

None. The weights are not distributed, so there are no public quantizations.

Notable innovations

  • · 1M context window (beta) at Sonnet-tier
  • · Adaptive thinking and context compaction
  • · Major OSWorld computer-use gains

Lineage

Incremental Sonnet refresh with 1M context beta.

Derived from

Claude Sonnet 4.5 2025-09-29

Sources