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  5. Claude Sonnet 4.5vsMercury 2.5
Updated Sep 2026

Claude Sonnet 4.5vsMercury 2.5

Mercury 2.5 is cheaper than Claude Sonnet 4.5 at $0.04/M vs $3/M input tokens.

Claude Sonnet 4.5 and Mercury 2.5 compared across 3 shared prompts
SpecClaude Sonnet 4.5Mercury 2.5
Input price$3/M tokens$0.04/M tokens
Output price$15/M tokens$0.15/M tokens
Context window200K tokens260K tokens
WeightsClosed—
Free API (OpenRouter)NoNo
ReleasedSep 2025Sep 2026
Side by side

Same prompt, both answers

Opening lines from 2 of the 3 prompts both answered. Formatting stripped, words untouched.

Simple 7-Ingredient Recipe

Create a simple recipe for a delicious dish (sweet or savory) using only 7 common pantry ingredients. Include a creative name for the dish…

Claude Sonnet 4.5165 words
Golden Pantry Frittata Ingredients: 6 eggs 1 cup shredded cheese (cheddar or mozzarella) 1 onion, diced 2 cloves garlic, minced 2 tablespoons olive oil Salt and pepper to taste 1/2 teaspoon dried herbs (oregano, basil, or Italian seasoning) Instructions: Preheat your oven to 375°F (190°C).
Read the full answer
Mercury 2.5190 words
Pantry Pasta Primavera Prep Time: 5 minutes Cook Time: 15 minutes Servings: 2 Ingredients (7 Common Pantry Items) Pasta (spaghetti, penne, or fusilli) – 8 oz Canned crushed tomatoes – 1 can (14 oz) Olive oil – 3 tablespoons Garlic powder – 1 teaspoon Dried oregano – 1 teaspoon Parmesan cheese (grated) – ½ cup Salt and…
Read the full answer

Explain Like I'm a Specific Expert

Explain how a large language model (like GPT or Claude) learns and generates text to each of these three audiences: 1. **An experienced…

Claude Sonnet 4.5831 words
For the Software Engineer Think of it like building a massive distributed key-value store, except instead of exact lookups, you're doing fuzzy pattern matching across billions of parameters.
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Mercury 2.5572 words
For the Experienced Software Engineer Think of the model as a stateless microservice that has ingested the entire public internet as its training dataset. During the training phase, it performs a massive distributed optimization job, adjusting internal weights to minimize a loss function based on next-token prediction.
Read the full answer
Our Verdict
Claude Sonnet 4.5
Claude Sonnet 4.5
Mercury 2.5
Mercury 2.5

Not enough votes to call it. On the specs, nothing separates them.

Mercury 2.5 costs 100x less per token.

Too close to call
API pricing

Cost per 1M tokens

Claude Sonnet 4.5
Input
$3.00
Output
$15.00
Mercury 2.5
Input
$0.04
75× cheaper
Output
$0.15
100× cheaper

Mercury 2.5 is cheaper on both: 75× input, 100× output.

Where to run it

5 hosts

Claude Sonnet 4.54 hosts
HostInOutContextUptime
Amazon Bedrock$3.00 in·$15.00 out·1M·99.9% upAzure AI Foundry$3.00 in·$15.00 out·200k·97.5% upAnthropic$3.00 in·$15.00 out·1M·100% upGoogle Vertex AI$3.00 in·$15.00 out·1M·99.9% up
Mercury 2.51 host
HostInOutContextUptime
Inception$0.04 in·$0.15 out·260k·100% up

Per million tokens. Prices and uptime via OpenRouter, checked 22 Sep 2026.

Research

What we learned reading every model

FAQ

Common questions

Claude Sonnet 4.5 is developed by Anthropic while Mercury 2.5 is developed by Inception. Claude Sonnet 4.5 has a 200K token context window vs Mercury 2.5's 260K. You can compare their actual outputs across 3 challenges on Rival to see how they differ in practice.

It depends on your use case. Claude Sonnet 4.5 and Mercury 2.5 each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 3 challenges so you can judge which fits your needs best.

Claude Sonnet 4.5 costs $3/M input tokens and Mercury 2.5 costs $0.04/M input tokens. Mercury 2.5 is $2.96/M cheaper per input. Check their side-by-side outputs on Rival to see if the price difference is justified by quality.

This page shows a side-by-side comparison of Claude Sonnet 4.5 and Mercury 2.5 across shared challenges. You can vote on which model produced the better output in a blind duel. Browsing and voting are free. No account is needed to look; signing in only saves your votes and likes.

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Model pages

Claude Sonnet 4.5 logo
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