Claude Sonnet 4vsMercury 2
Mercury 2 is cheaper than Claude Sonnet 4 at $0.25/M vs $3/M input tokens.
| Spec | Claude Sonnet 4 | Mercury 2 |
|---|---|---|
| Input price | $3/M tokens | $0.25/M tokens |
| Output price | $15/M tokens | $0.75/M tokens |
| Context window | 200K tokens | 128K tokens |
| Weights | Closed | — |
| Free API (OpenRouter) | No | No |
| Released | May 2025 | Mar 2026 |
Our Verdict
Claude Sonnet 4
Mercury 2Runner-up
Not enough votes to call it. On the specs, Claude Sonnet 4 has the edge: bigger model tier, bigger context window, major provider backing.
Mercury 2 costs 20x less per token.
Too close to call
API pricing
Cost per 1M tokens
Claude Sonnet 4
Input
$3.00
Output
$15.00
Mercury 2
Input
$0.25
12× cheaper
Output
$0.75
20× cheaper
Mercury 2 is cheaper on both: 12× input, 20× output.
Where to run it
3 hosts
Claude Sonnet 42 hosts
Mercury 21 host
Per million tokens. Prices and uptime via OpenRouter, checked 9 Sep 2026.
Writing DNA
Style Comparison
Similarity
40%
Claude Sonnet 4 uses 8.6x more emoji
Claude Sonnet 4
Mercury 2
64%Vocabulary53%
81wSentence Length22w
0.56Hedging0.40
4.5Bold6.6
6.6Lists2.6
0.70Emoji0.08
1.59Headings0.87
0.20Transitions0.14
Based on 28 + 23 text responses
Research
What we learned reading every model
FAQ
Common questions
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