What is the difference between GPT-4.5 and Mercury 2.5?

GPT-4.5 is developed by OpenAI while Mercury 2.5 is developed by Inception. GPT-4.5 has a 128K token context window vs Mercury 2.5's 260K. You can compare their actual outputs across 4 challenges on Rival to see how they differ in practice.

Which is better, GPT-4.5 or Mercury 2.5?

It depends on your use case. GPT-4.5 and Mercury 2.5 each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 4 challenges so you can judge which fits your needs best.

How much does GPT-4.5 cost compared to Mercury 2.5?

GPT-4.5 costs $75/M input tokens and Mercury 2.5 costs $0.04/M input tokens. Mercury 2.5 is $74.96/M cheaper per input. Check their side-by-side outputs on Rival to see if the price difference is justified by quality.

How can I compare GPT-4.5 and Mercury 2.5 on Rival?

This page shows a side-by-side comparison of GPT-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.

Updated Sep 2026

GPT-4.5vsMercury 2.5

Mercury 2.5 is cheaper than GPT-4.5 at $0.04/M vs $75/M input tokens.

GPT-4.5 and Mercury 2.5 compared across 4 shared prompts
Spec	GPT-4.5	Mercury 2.5
Input price	$75/M tokens	$0.04/M tokens
Output price	$150/M tokens	$0.15/M tokens
Context window	128K tokens	260K tokens
Free API (OpenRouter)	No	No
Released	Feb 2025	Sep 2026

Side by side

Same prompt, both answers

Opening lines from 3 of the 4 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…

GPT-4.5153 words

Sweet Cinnamon Sugar Swirls Ingredients: 1 sheet puff pastry, thawed 1/4 cup granulated sugar 1 tablespoon cinnamon 2 tablespoons melted butter Pinch of salt 1 teaspoon vanilla extract Powdered sugar (optional for dusting) Prep Time: 10 minutes Cook Time: 15 minutes Total Time: 25 minutes Instructions: Preheat your…

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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-4.5202 words

Longevity Optimization Protocol (3-Month Timeline) Month 1: Establish Foundational Habits & Baseline Metrics Full biomarker panel & epigenetic age test. Wearable setup: Oura/WHOOP, CGM, HR chest strap. Diet: 5-day keto (70/25/5) + 2 carb-refeed days; 16:8 IF + weekly 24-h fast.

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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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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…

GPT-4.5322 words

Dish Title: "Ocean & Earth Symphony: Kombu-Cured Venison, Sea Urchin Custard, Black Garlic Soil, and Smoked Cherry Blossom Emulsion" Conceptual Narrative: This composition embodies the delicate interplay between land and sea, exploring the subtle yet profound connection between umami-rich sea elements and earthy forest…

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Mercury 2.5827 words

Dish Title: Chronos and Mycelium Conceptual Narrative This dish explores the intersection of time, decay, and rebirth. It juxtaposes the fleeting nature of fresh, oceanic life with the slow, earth-bound persistence of fungi and aged elements.

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Our Verdict

GPT-4.5

Mercury 2.5

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

Mercury 2.5 costs 1000x less per token.

Too close to call

Reviewing agent-written code?See a Brief PR report

API pricing

Cost per 1M tokens

GPT-4.5

Input

$75.00

Output

$150.00

Mercury 2.5

Input

$0.04

1875× cheaper

Output

$0.15

1000× cheaper

Mercury 2.5 is cheaper on both: 1875× input, 1000× output.

Where to run it

1 host

GPT-4.5

No hosts listed on OpenRouter.

Mercury 2.51 host

HostInOutContextUptime

Inception$0.04 in$0.15 out260k100% up

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

Research

What we learned reading every model

FAQ

Common questions

Keep exploring

More comparisons

Same prompt, both answers

Simple 7-Ingredient Recipe

Advanced Longevity Plan (Biohacker)

Michelin Star Recipe Design

Cost per 1M tokens

1 host

What we learned reading every model

Common questions

What is the difference between GPT-4.5 and Mercury 2.5?

Which is better, GPT-4.5 or Mercury 2.5?

How much does GPT-4.5 cost compared to Mercury 2.5?

How can I compare GPT-4.5 and Mercury 2.5 on Rival?

More comparisons

Against the newest arrivals

Same lab, same size, long tail

Model pages

Same prompt, both answers

Simple 7-Ingredient Recipe

Advanced Longevity Plan (Biohacker)

Michelin Star Recipe Design

Cost per 1M tokens

1 host

What we learned reading every model

Common questions

What is the difference between GPT-4.5 and Mercury 2.5?

Which is better, GPT-4.5 or Mercury 2.5?

How much does GPT-4.5 cost compared to Mercury 2.5?

How can I compare GPT-4.5 and Mercury 2.5 on Rival?

More comparisons

Against the newest arrivals

Same lab, same size, long tail

Model pages