Skip to content
Rival
How it worksPrivacyTerms
Explore all of Rival

Explore

  • Compare Models
  • All Models
  • Image Comparison
  • Audio Comparison
  • Image Generation
  • Best AI For...
  • Arena
  • API Pricing
  • Challenges

Discover

  • SubjectiveBench
  • Default Index
  • Research
  • Research downloads
  • Rival Kits
  • Find your AI taste
  • UI Glow-Up
  • VoiceLock
  • Cost Cutter
  • Agent skills
  • Benchmarks vs Vibes
  • Brief
  • Jailbreak
  • Model Updates
  • Provider Status
  • AI Creators

Connect

  • Methodology
  • Advertise
  • Partnerships
  • Privacy Policy
  • Terms
  • RSS Feed
  1. Home
  2. /
  3. Compare
  4. /
  5. Claude Opus 5.5vsGrok 4
Updated Sep 2026

Claude Opus 5.5vsGrok 4

Grok 4 is cheaper than Claude Opus 5.5 at $3/M vs $4/M input tokens.

Claude Opus 5.5 and Grok 4 compared across 19 shared prompts
SpecClaude Opus 5.5Grok 4
Input price$4/M tokens$3/M tokens
Output price$20/M tokens$15/M tokens
Context window1.0M tokens256K tokens
WeightsClosed—
Free API (OpenRouter)NoNo
ReleasedSep 2026Jul 2025
Side by side

Same prompt, both answers

Opening lines from 6 of the 19 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 5.5300 words
Midnight Silk Noodles Creamy, tangy peanut noodles with a gentle kick, ready faster than takeout. Serves: 2 Prep time: 5 minutes Cook time: 10 minutes Total time: 15 minutes The 7 Ingredients 8 oz (225 g) spaghetti (or any long noodle) ¼ cup creamy peanut butter 3 tablespoons soy sauce 1 tablespoon honey (or sugar) 1…
Read the full answer
Grok 4234 words
Recipe: Pantry Pirate's Tomato Tango This is a simple savory pasta dish that's hearty, flavorful, and perfect for a quick weeknight meal. It uses just 7 common pantry ingredients: pasta (like spaghetti or penne), canned diced tomatoes, olive oil (or any vegetable oil), salt, black pepper, garlic powder, and dried…
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 5.53,435 words
The Transistor in 1920: A Counterfactual Through 1980 First, a Reality Check on the Premise A transistor "invented" in 1920 would not have changed the world in 1920. The actual 1947 transistor rested on three foundations that did not exist yet: Quantum theory of solids.
Read the full answer
Grok 41,310 words
Below is a detailed, speculative analysis of the hypothetical scenario where the transistor is invented in 1920 (perhaps by an inventor like Julius Lilienfeld, who historically patented a field-effect transistor concept in 1925, but with successful prototyping and refinement by the mid-1920s).
Read the full answer

Mini LBO Underwrite

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

Claude Opus 5.5900 words
HarborTech Services: 5-Year LBO Underwriting Conventions: $m. Interest is charged on beginning-of-year balances, which avoids circularity. Term Loan (TL) amortization is 1% of the original $480m, or $4.8m per year. Mezz PIK accrues to principal. All FCF after mandatory debt service sweeps to the TL.
Read the full answer
Grok 4754 words
Below is a concise analysis based solely on the provided information. All calculations are shown clearly with step-by-step math. Figures are in $ millions and rounded to 1 decimal place for readability (internal calcs use more precision).
Read the full answer

Debug This Architecture

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

Claude Opus 5.52,280 words
Architecture Review: Real-Time Collaborative Editor The most serious problems cluster in three areas: the sync model (client-clock LWW), cross-server propagation (per-server WebSockets with DB polling), and the CDN/auth layer, which can leak data between users. Issues are grouped by area below.
Read the full answer
Grok 41,551 words
Below, I'll systematically identify potential failure modes, race conditions, and scaling bottlenecks in the described architecture for a real-time collaborative document editor. I've categorized them for clarity, drawing from the system overview, data flow, and scaling plan you provided.
Read the full answer

Adversarial Contract Review

Here is a contract for a software consulting engagement: --- SOFTWARE CONSULTING AGREEMENT This Agreement is entered into between TechCorp…

Claude Opus 5.54,420 words
Contractor-Side Review of the Software Consulting Agreement Overall assessment: This agreement is heavily one-sided. Nearly every clause shifts risk, cost, or control to the Contractor, and several provisions interact to create compounding exposure.
Read the full answer
Grok 41,680 words
Below, I'll analyze the provided Software Consulting Agreement clause by clause. My analysis is based on general principles of U.S. contract law (assuming a U.S. context, as the contract appears to be drafted in a style common to U.S. agreements; if this is in another jurisdiction, local laws may vary).
Read the full answer

Michelin Star Recipe Design

Design an innovative recipe for a multi-component dish worthy of a Michelin 3-star restaurant. The recipe should feature an unusual…

Claude Opus 5.52,253 words
"Hive & Tide" Langoustine, Beeswax, White Chocolate & Oscietra Caviar, Hay-Baked Celeriac, Fermented Green Strawberry, Sea Buckthorn I. The Concept Most coastal menus celebrate the meeting of sea and land. This dish is about a stranger, quieter meeting: the meadow and the seabed, the bee and the langoustine.
Read the full answer
Grok 41,233 words
Below is my design for an innovative, multi-component dish titled "Abyssal Bloom". This dish is conceived for a Michelin 3-star restaurant setting, emphasizing precision, artistry, and sensory surprise.
Read the full answer
Our Verdict
Claude Opus 5.5
Claude Opus 5.5
Grok 4
Grok 4Runner-up

Not enough votes to call it. On the specs, Claude Opus 5.5 has the edge: newer, bigger context window.

Too close to call

Reviewing agent-written code?See a Brief PR report

API pricing

Cost per 1M tokens

Claude Opus 5.5
Input
$4.00
Output
$20.00
Grok 4
Input
$3.00
1.3× cheaper
Output
$15.00
1.3× cheaper

Grok 4 is cheaper on both: 1.3× input, 1.3× output.

Where to run it

4 hosts

Claude Opus 5.54 hosts
HostInOutContextUptime
Amazon Bedrock$4.00 in·$20.00 out·1M·99.8% upAzure AI Foundry$4.00 in·$20.00 out·1M·100% upAnthropic$4.00 in·$20.00 out·1M·100% upGoogle Vertex AI$4.00 in·$20.00 out·1M·100% up
Grok 4

No hosts listed on OpenRouter.

Per million tokens. Prices and uptime via OpenRouter, checked 25 Sep 2026.

Research

What we learned reading every model

FAQ

Common questions

Claude Opus 5.5 is developed by Anthropic while Grok 4 is developed by xAI. Claude Opus 5.5 has a 1.0M token context window vs Grok 4's 256K. You can compare their actual outputs across 19 challenges on Rival to see how they differ in practice.

It depends on your use case. Claude Opus 5.5 and Grok 4 each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 19 challenges so you can judge which fits your needs best.

Claude Opus 5.5 costs $4/M input tokens and Grok 4 costs $3/M input tokens. Grok 4 is $1.00/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 5.5 and Grok 4 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.

Keep exploring

More comparisons

Against the newest arrivals

Claude Opus 5.5 logoSolar Mini 4 logo
Claude Opus 5.5 vs Solar Mini 4Landed Sep 2026
Grok 4 logoQwen3.8 Max Prime logo
Grok 4 vs Qwen3.8 Max PrimeLanded Sep 2026
Claude Opus 5.5 logoGLM 5.3 Prime logo
Claude Opus 5.5 vs GLM 5.3 PrimeLanded Sep 2026
Grok 4 logoQwen3.8 Omni Flash logo
Grok 4 vs Qwen3.8 Omni FlashLanded Sep 2026
Claude Opus 5.5 logoCommand A+ logo
Claude Opus 5.5 vs Command A+Landed Sep 2026
Grok 4 logoGPT-6 Luna Pro logo
Grok 4 vs GPT-6 Luna ProLanded Sep 2026
Claude Opus 5.5 logoGPT-6 Sol Pro logo
Claude Opus 5.5 vs GPT-6 Sol ProLanded Sep 2026
Grok 4 logoGPT-6 Luna logo
Grok 4 vs GPT-6 LunaLanded Sep 2026

Same lab, same size, long tail

Claude Opus 5.5 logoClaude Opus 4.6 logo
Claude Opus 5.5 vs Claude Opus 4.6Same lab
Claude Opus 5.5 logoClaude Fable 5.1 logo
Claude Opus 5.5 vs Claude Fable 5.1Same lab
Grok 4 logoGrok 4.7 logo
Grok 4 vs Grok 4.7Same lab
Grok 4 logoGrok 4.6 logo
Grok 4 vs Grok 4.6Version compare
Claude Opus 5.5 logoGrok 3 logo
Claude Opus 5.5 vs Grok 3Cross-provider
Claude Opus 5.5 logoGrok 3 Beta logo
Claude Opus 5.5 vs Grok 3 BetaCross-provider
Claude Opus 5.5 logoGrok 3 Mini Beta logo
Claude Opus 5.5 vs Grok 3 Mini BetaCross-provider
Claude Opus 5.5 logoGrok 4 Fast (free) logo
Claude Opus 5.5 vs Grok 4 Fast (free)Same size

Model pages

Claude Opus 5.5 logo
Claude Opus 5.519 outputs, specs and price
Grok 4 logo
Grok 457 outputs, specs and price
Rival
How it worksPrivacyTerms
Explore all of Rival

Explore

  • Compare Models
  • All Models
  • Image Comparison
  • Audio Comparison
  • Image Generation
  • Best AI For...
  • Arena
  • API Pricing
  • Challenges

Discover

  • SubjectiveBench
  • Default Index
  • Research
  • Research downloads
  • Rival Kits
  • Find your AI taste
  • UI Glow-Up
  • VoiceLock
  • Cost Cutter
  • Agent skills
  • Benchmarks vs Vibes
  • Brief
  • Jailbreak
  • Model Updates
  • Provider Status
  • AI Creators

Connect

  • Methodology
  • Advertise
  • Partnerships
  • Privacy Policy
  • Terms
  • RSS Feed