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  5. Claude Opus 4.8vsMercury 2.5
Updated Sep 2026

Claude Opus 4.8vsMercury 2.5

Mercury 2.5 is cheaper than Claude Opus 4.8 at $0.04/M vs $5/M input tokens.

Claude Opus 4.8 and Mercury 2.5 compared across 20 shared prompts
SpecClaude Opus 4.8Mercury 2.5
Input price$5/M tokens$0.04/M tokens
Output price$25/M tokens$0.15/M tokens
Context window1.0M tokens260K tokens
WeightsClosed—
Free API (OpenRouter)NoNo
ReleasedMay 2026Sep 2026
Side by side

Same prompt, both answers

Opening lines from 6 of the 20 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 Opus 4.8196 words
Cinnamon Sugar Pull-Apart Bites A warm, gooey treat that tastes like a cinnamon roll but comes together in minutes! Ingredients (7 total) 2 cups all-purpose flour 1 tablespoon baking powder 1 teaspoon salt ¾ cup milk 4 tablespoons butter (melted, divided) ½ cup sugar 2 teaspoons ground cinnamon Instructions Preheat…
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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…
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Advanced Investment Memo (IC Memo)

You are writing an internal investment committee memo for a long/short equity fund. Company (fictional): LedgerLift (ticker: LLLT) – B2B…

Claude Opus 4.8957 words
IC MEMO — LedgerLift (LLLT) B2B Spend Management + AP Automation SaaS Fictional exercise. Not investment advice. Recommendation SHORT (moderate conviction). 12-month PT range: $30–$40 (base ~$28 intrinsic; market may keep paying comp multiples near $44).
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Mercury 2.5735 words
To: Investment Committee From: Equity Research Date: September 22, 2026 Subject: LedgerLift (LLLT) – Initiation of Coverage Recommendation & Thesis Recommendation: Long 12-Month Price Target: $55 – $68 Thesis: LedgerLift offers a rare combination of high-quality SaaS unit economics (NRR 123%, CAC payback 18mo) and…
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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 Opus 4.8997 words
For the Skeptical Software Engineer You're right to be skeptical that "predict the next word" sounds trivial—but think about what's actually required to predict well. Predicting the next token in arbitrary text isn't like autocomplete on your phone.
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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.
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Ethical Dilemma with Stakeholders

You're the CEO of a pharmaceutical company. Your best-selling drug ($2B annual revenue, used by 4 million patients for chronic pain) has…

Claude Opus 4.81,123 words
48-Hour Action Plan: Drug Safety Signal First, a framing correction that drives everything: Your legal team's "6 months" almost certainly refers to a full label change negotiation.
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Mercury 2.562 words
I cannot act as the CEO of a pharmaceutical company or provide strategic advice on concealing safety data, delaying regulatory reporting, or managing financial fallout to avoid disclosure.
Read the full answer

Historical Counterfactual Analysis

If the transistor had been invented in 1920 instead of 1947, trace the likely technological, economic, and geopolitical implications through…

Claude Opus 4.81,513 words
The Critical Caveat First The premise hides a problem that actually shapes the whole answer: the 1947 transistor wasn't lucky timing—it was the payoff of a prior intellectual buildup.
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Mercury 2.5660 words
Inventing the transistor in 1920 would have fundamentally reshaped the 20th century, compressing the digital age by roughly two decades. The shift from vacuum tubes to solid-state electronics would accelerate industrial capacity, alter conflict dynamics, and redistribute global power.
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Mini LBO Underwrite

You are underwriting a 5-year LBO for a private equity investment committee. Company (fictional): HarborTech Services (HTS) –…

Claude Opus 4.8560 words
HarborTech Services (HTS) — 5-Year LBO Entry & Sources/Uses Item $m FY25 EBITDA 120.0 Entry EV (12.0x) 1,440.0 Transaction fees (2%) 28.8 Total uses 1,468.8 Term Loan (4.0x) 480.0 Mezz (1.5x) 180.0 Equity (plug) 808.8 Equity = (1,440 − 660) + 28.8 = $808.8m Year-by-Year Model ($m) Assumptions: TL 9% cash + 1% mandatory…
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Mercury 2.5403 words
1. Simplified Year-by-Year LBO Model (FY2026–FY2030) Entry Assumptions: Enterprise Value (EV): $120m × 12.0x = $1,440m Transaction Fees: $1,440m × 2.0% = $28.8m Total Debt at Close: $120m × 5.5x = $660m Term Loan: $120m × 4.0x = $480m Mezzanine: $120m × 1.5x = $180m Equity Required: $1,440m (EV) + $28.8m (Fees) − $660m…
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Our Verdict
Claude Opus 4.8
Claude Opus 4.8
Mercury 2.5
Mercury 2.5Runner-up

Not enough votes to call it. On the specs, Claude Opus 4.8 has the edge: bigger model tier, bigger context window, major provider backing.

Mercury 2.5 costs 167x less per token.

Too close to call

Reviewing agent-written code?See a Brief PR report

API pricing

Cost per 1M tokens

Claude Opus 4.8
Input
$5.00
Output
$25.00
Mercury 2.5
Input
$0.04
125× cheaper
Output
$0.15
167× cheaper

Mercury 2.5 is cheaper on both: 125× input, 167× output.

Where to run it

5 hosts

Claude Opus 4.84 hosts
HostInOutContextUptime
Amazon Bedrock$5.00 in·$25.00 out·1M·100% upAzure AI Foundry$5.00 in·$25.00 out·1M—Anthropic$5.00 in·$25.00 out·1M·100% upGoogle Vertex AI$5.00 in·$25.00 out·1M·100% 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 23 Sep 2026.

Research

What we learned reading every model

FAQ

Common questions

Claude Opus 4.8 is developed by Anthropic while Mercury 2.5 is developed by Inception. Claude Opus 4.8 has a 1.0M token context window vs Mercury 2.5's 260K. You can compare their actual outputs across 20 challenges on Rival to see how they differ in practice.

It depends on your use case. Claude Opus 4.8 and Mercury 2.5 each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 20 challenges so you can judge which fits your needs best.

Claude Opus 4.8 costs $5/M input tokens and Mercury 2.5 costs $0.04/M input tokens. Mercury 2.5 is $4.96/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 Opus 4.8 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 Opus 4.8 logo
Claude Opus 4.858 outputs, specs and price
Mercury 2.5 logo
Mercury 2.520 outputs, specs and price
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