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  5. GPT-4vsMercury 2.5
Updated Sep 2026

GPT-4vsMercury 2.5

Mercury 2.5 is cheaper than GPT-4 at $0.04/M vs $30/M input tokens.

GPT-4 and Mercury 2.5 compared across 18 shared prompts
SpecGPT-4Mercury 2.5
Input price$30/M tokens$0.04/M tokens
Output price$60/M tokens$0.15/M tokens
Context window8K tokens260K tokens
WeightsClosed—
Free API (OpenRouter)NoNo
ReleasedMay 2023Sep 2026
Side by side

Same prompt, both answers

Opening lines from 6 of the 18 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…

GPT-4441 words
An early invention of the transistor in 1920 would have had profound implications across numerous domains, drastically altering the course of history. Technological Implications: WWII: The transistor, a fundamental component of modern electronic devices, could have advanced the technology used in WWII significantly.
Read the full answer
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

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…

GPT-4495 words
Experienced Software Engineer: How does a language model like GPT produce intelligent behavior? Think of it as a highly specialized function in your code. This function has been trained on a large amount of text data, and it's main goal is to predict the next word in a sentence given the previous words.
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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

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.…

GPT-4298 words
Weak Claim 1 - Solution: While the claim that the proprietary EEG headband uses advanced ML to decode neural patterns into text with 94% accuracy is impressive, it doesn't address concerns about user comfort, ease of use, or aesthetics.
Read the full answer
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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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…

GPT-4172 words
Dish Name: Hearty Baked Beans Fiesta Ingredients: 2 cans of baked beans 1 large onion 3 cloves of garlic 1 bell pepper 1 can of sweet corn 2 tablespoons of olive oil Salt & pepper to taste Instructions: Preheat your oven to 350°F (175°C). Dice the onion, bell pepper, and mince the garlic.
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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 Longevity Plan (Biohacker)

Develop a comprehensive, cutting-edge 3-month longevity plan for a biohacker aiming to optimize longevity, physical and cognitive…

GPT-4404 words
3-Month Longevity Plan Dietary Protocols Month 1: Ketogenic Diet This diet is high in fats, moderate in protein, and low in carbohydrates. It helps in burning fat more effectively. Breakfast: 2 eggs, avocado, and mixed vegetables. Lunch: Grilled salmon with a side of asparagus. Dinner: Stir-fried chicken with broccoli.
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Mercury 2.5610 words
3-Month Biohacking Longevity & Performance Plan Disclaimer: I am an AI, not a physician or certified health professional. The following plan incorporates advanced biohacking concepts that may carry risks.
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Adversarial Contract Review

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

GPT-4533 words
SCOPE: The lack of specificity can be used against the contractor in that the client can modify the scope of work at will without renegotiating the price. This could lead to the contractor working beyond the initially agreed upon parameters without additional pay.
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Mercury 2.5501 words
Here is an analysis of the contract clauses that pose significant risk to the contractor, along with suggested modifications and legal reasoning. Scope and Compensation (Clause 1) Risk: The client can expand the project indefinitely without paying extra.
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Our Verdict
GPT-4
GPT-4
Mercury 2.5
Mercury 2.5

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

Mercury 2.5 costs 400x less per token.

Too close to call

Reviewing agent-written code?See a Brief PR report

API pricing

Cost per 1M tokens

GPT-4
Input
$30.00
Output
$60.00
Mercury 2.5
Input
$0.04
750× cheaper
Output
$0.15
400× cheaper

Mercury 2.5 is cheaper on both: 750× input, 400× output.

Where to run it

3 hosts

GPT-42 hosts
HostInOutContextUptime
Azure AI Foundry$30.00 in·$60.00 out·8k·100% upOpenAI$30.00 in·$60.00 out·8k·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 22 Sep 2026.

Research

What we learned reading every model

FAQ

Common questions

GPT-4 is developed by OpenAI while Mercury 2.5 is developed by Inception. GPT-4 has a 8K token context window vs Mercury 2.5's 260K. You can compare their actual outputs across 18 challenges on Rival to see how they differ in practice.

It depends on your use case. GPT-4 and Mercury 2.5 each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 18 challenges so you can judge which fits your needs best.

GPT-4 costs $30/M input tokens and Mercury 2.5 costs $0.04/M input tokens. Mercury 2.5 is $29.96/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 GPT-4 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

GPT-4 logo
GPT-426 outputs, specs and price
Mercury 2.5 logo
Mercury 2.520 outputs, specs and price
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