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  5. GPT-5.4 NanovsGPT-6 Luna Pro
Updated Sep 2026

GPT-5.4 NanovsGPT-6 Luna Pro

GPT-6 Luna Pro is cheaper than GPT-5.4 Nano at $0.1/M vs $0.2/M input tokens.

GPT-5.4 Nano and GPT-6 Luna Pro compared across 20 shared prompts
SpecGPT-5.4 NanoGPT-6 Luna Pro
Input price$0.2/M tokens$0.1/M tokens
Output price$1.25/M tokens$0.5/M tokens
Context window400K tokens1.1M tokens
WeightsClosedClosed
Free API (OpenRouter)NoNo
ReleasedMar 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…

GPT-5.4 Nano184 words
Dish Name: Golden Garlic Chickpea Clouds Pantry Ingredients (7 total) Chickpeas (canned or cooked) – 1 can (15 oz), drained Olive oil – 2 tbsp Garlic – 3 cloves (or 1–2 tsp minced garlic) Lemon – 1 (you’ll use the juice) Salt – 1/2 tsp (plus to taste) Black pepper – 1/4 tsp (plus to taste) Paprika – 1 tsp Estimated…
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GPT-6 Luna Pro127 words
Golden Pantry Pancakes Fluffy, lightly sweet pancakes made with everyday staples. Makes: About 6 small pancakes Prep time: 5 minutes Cook time: 10 minutes Ingredients 1 cup all-purpose flour 1 cup milk 1 egg 2 tablespoons sugar 1 teaspoon baking powder ¼ teaspoon salt 2 tablespoons butter, melted (plus a little for the…
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Beginner's Longevity Plan

Outline a simple, actionable 1-month plan for someone starting their journey towards better health and longevity. Focus on 3 key areas…

GPT-5.4 Nano785 words
Here’s a simple, actionable 1‑month plan focused on 3 key areas: food, movement, and sleep/stress. It’s designed for beginners and is intentionally realistic. Overall goal (simple) Each week, build consistency in: Food: more whole foods + fewer “defaults” Exercise: daily movement + 2–3 strength sessions/week Sleep +…
Read the full answer
GPT-6 Luna Pro327 words
A simple 1-month plan for better health and longevity Choose three foundations: eating well, moving regularly, and sleeping consistently. Aim for steady habits, not perfection. Diet: Make nourishing choices easier Week 1: Add one serving of fruit or vegetables to one meal each day.
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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…

GPT-5.4 Nano1,801 words
Below is a structured list of likely failure modes, race conditions, and scaling bottlenecks in your design, with a concrete mitigation and trade-offs for each. (Some issues are “systemic” because the architecture relies on client clocks, per-server WebSockets, polling, and periodic full snapshots.)
Read the full answer
GPT-6 Luna Pro1,906 words
The main architectural risk is that this design treats collaborative editing as ordinary “last write wins” data storage. It is not: edits need a well-defined order, reliable propagation, and a conflict model that preserves concurrent work.
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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-5.4 Nano1,859 words
I’m not a lawyer, but I can flag contract terms that (a) are unusually one‑sided, (b) create open‑ended or high‑risk obligations, or (c) can be interpreted in ways that materially disadvantage the contractor. I’ll then suggest specific counter‑edits and explain the typical legal/contracting rationale.
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GPT-6 Luna Pro2,116 words
This agreement is heavily one-sided. Several terms let the Client expand the work, delay or deny payment, claim ownership of the Contractor’s existing materials, and expose the Contractor to potentially unlimited liability.
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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-5.4 Nano2,782 words
Below is a comprehensive 3‑month (12‑week) longevity + performance plan designed for a biohacker who wants measurable improvements in longevity markers, physical output, body composition, metabolic health, and cognitive function.
Read the full answer
GPT-6 Luna Pro2,057 words
12-week longevity and performance plan This is a structured starting plan for a generally healthy adult—not a diagnosis or a substitute for medical care. The best longevity interventions are still the unglamorous ones: not smoking, regular exercise, adequate sleep, a high-quality diet, healthy blood pressure and…
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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-5.4 Nano677 words
Here are the three weakest claims in the deck, why they’re weak (with specific reasoning/evidence gaps), and concrete ways to strengthen them. Weakest claim: “Reads your brainwaves to predict what you want to type before you think it.”
Read the full answer
GPT-6 Luna Pro401 words
“94% accuracy” and “works with any language, any device” Why it’s weak: “Accuracy” is undefined. It could mean classifying a small set of prompted words in a controlled lab—not reliably generating free-form text.
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Our Verdict
GPT-6 Luna Pro
GPT-6 Luna Pro
GPT-5.4 Nano
GPT-5.4 NanoRunner-up

Not enough votes to call it. On the specs, GPT-6 Luna Pro has the edge: bigger model tier, newer, bigger context window.

Slight edge

Reviewing agent-written code?See a Brief PR report

API pricing

Cost per 1M tokens

GPT-5.4 Nano
Input
$0.20
Output
$1.25
GPT-6 Luna Pro
Input
$0.10
2.0× cheaper
Output
$0.50
2.5× cheaper

GPT-6 Luna Pro is cheaper on both: 2.0× input, 2.5× output.

Where to run it

4 hosts

GPT-5.4 Nano2 hosts
HostInOutContextUptime
Azure AI Foundry$0.20 in·$1.25 out·400k·100% upOpenAI$0.20 in·$1.25 out·400k·99.9% up
GPT-6 Luna Pro2 hosts
HostInOutContextUptime
Azure AI Foundry$0.10 in·$0.50 out·1.1M·98.6% upOpenAI$0.10 in·$0.50 out·1.1M·99.9% up

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

Research

What we learned reading every model

FAQ

Common questions

Both are developed by OpenAI but target different use cases. GPT-5.4 Nano has a 400K token context window vs GPT-6 Luna Pro's 1.1M. You can compare their actual outputs across 20 challenges on Rival to see how they differ in practice.

It depends on your use case. GPT-5.4 Nano and GPT-6 Luna Pro 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.

GPT-5.4 Nano costs $0.2/M input tokens and GPT-6 Luna Pro costs $0.1/M input tokens. GPT-6 Luna Pro is $0.10/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-5.4 Nano and GPT-6 Luna Pro 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-5.4 Nano logo
GPT-5.4 Nano53 outputs, specs and price
GPT-6 Luna Pro logo
GPT-6 Luna Pro20 outputs, specs and price
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