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  5. Grok 4.5vsMercury 2.5
Updated Sep 2026

Grok 4.5vsMercury 2.5

Mercury 2.5 is cheaper than Grok 4.5 at $0.04/M vs $2/M input tokens.

Grok 4.5 and Mercury 2.5 compared across 20 shared prompts
SpecGrok 4.5Mercury 2.5
Input price$2/M tokens$0.04/M tokens
Output price$6/M tokens$0.15/M tokens
Context window500K tokens260K tokens
WeightsClosed—
Free API (OpenRouter)NoNo
ReleasedJul 2026Sep 2026
Side by side

Same prompt, both answers

Opening lines from 6 of the 20 prompts both answered. Formatting stripped, words untouched.

Historical Counterfactual Analysis

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

Grok 4.51,578 words
Accelerated electronics from ~1920 would compress the digital and computational revolutions by roughly 20–30 years, reshaping WWII lethality and duration, advancing the Cold War into an earlier high-tech standoff, pulling the space race forward, creating an information-heavy economy by the 1950s–60s, and producing…
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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.
Read the full answer

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…

Grok 4.5903 words
IC MEMO: LedgerLift (LLLT) – Short 12-month PT: $22–35 Current: $46 Recommendation & Thesis Short. Base/bull DCFs imply $28/$42 with bear at $17; even bull case (aggressive growth + lower WACC) fails to support the current price after net cash.
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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…
Read the full answer

Startup Pitch Teardown

Here's a pitch deck summary for a startup called "MindMeld AI": **Slide 1 - Vision:** "We're building the future of human-AI collaboration.…

Grok 4.5808 words
The 3 weakest claims Solution accuracy: “decode neural patterns into text with 94% accuracy” (non-invasive consumer EEG headband, any language/device) Why weak: This is the single most scientifically implausible claim.
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Mercury 2.5544 words
Based on the pitch deck summary, here are the three weakest claims, along with an analysis of their vulnerabilities and concrete suggestions for improvement. The "Pre-Thought" Prediction Claim Claim: "MindMeld AI reads your brainwaves to predict what you want to type before you think it."
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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…

Grok 4.51,470 words
Immediate priority: Patient safety and full, rapid compliance with legal/regulatory obligations over short-term stock price or board pressure. Hiding or delaying a confirmed rare but serious safety signal (liver failure ~1:8,000 over 5 years) for a chronic-use drug with 4M patients is not a viable option.
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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

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…

Grok 4.5212 words
Spellbound Spaghetti (savory) A quick, cozy tomato pasta that tastes like it took far more effort. Serves 2. 7 pantry ingredients 8 oz (225 g) dry pasta (spaghetti, penne, or whatever you have) 2 Tbsp olive oil (or any neutral oil) 1 (14–15 oz) can diced or crushed tomatoes 1 tsp garlic powder 1 tsp dried oregano (or…
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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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Debug This Architecture

Here's the architecture for a real-time collaborative document editor (like Google Docs): **System Overview:** - Frontend: React SPA with…

Grok 4.51,572 words
Architecture Review: Real-Time Collaborative Document Editor This design has fundamental real-time and consistency problems. Several choices (client clocks, LWW, per-server WebSockets + DB polling, CDN-cached APIs, full HTML snapshots) will cause data loss, stale UI, and poor scale.
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Mercury 2.5672 words
Critical Analysis of Collaborative Editor Architecture Below is a detailed breakdown of failure modes, race conditions, and scaling bottlenecks, along with proposed solutions and their trade-offs.
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Our Verdict
Grok 4.5
Grok 4.5
Mercury 2.5
Mercury 2.5

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

Mercury 2.5 costs 40x less per token.

Too close to call

Reviewing agent-written code?See a Brief PR report

API pricing

Cost per 1M tokens

Grok 4.5
Input
$2.00
Output
$6.00
Mercury 2.5
Input
$0.04
50× cheaper
Output
$0.15
40× cheaper

Mercury 2.5 is cheaper on both: 50× input, 40× output.

Where to run it

2 hosts

Grok 4.51 host
HostInOutContextUptime
xAI$2.00 in·$6.00 out·500k·95.9% 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 23 Sep 2026.

Research

What we learned reading every model

FAQ

Common questions

Grok 4.5 is developed by xAI while Mercury 2.5 is developed by Inception. Grok 4.5 has a 500K 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. Grok 4.5 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.

Grok 4.5 costs $2/M input tokens and Mercury 2.5 costs $0.04/M input tokens. Mercury 2.5 is $1.96/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 Grok 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

Grok 4.5 logo
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