What Size AC Do I Need for My RV?

If your RV air conditioner struggles to keep up on hot days, the issue often comes down to size. An underpowered rooftop AC unit can leave your space feeling warm and humid, while an oversized unit may cycle too often and waste energy. Knowing what size AC you need for your RV is one of the most important steps toward consistent, efficient cooling on the road.

This guide walks through how RV air conditioning works, how to calculate the right cooling capacity for your RV size, and what factors influence performance. We’ll also look at modern rooftop air conditioner options, including variable-speed systems like the Furrion Chill® Cube, to help you make a confident, informed decision.

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Understanding RV Air Conditioner Sizing

RV air conditioners are sized using BTUs, or British Thermal Units. BTUs measure how much heat an air conditioning system can remove from a space in one hour. The higher the BTU rating, the greater the cooling capacity.

In RVs, common rooftop AC units typically range from around 13,500 BTUs to 18,000 BTUs. The right size depends on more than just the length of your RV. Interior square footage, insulation quality, climate, and airflow all play a role in how effectively an RV air conditioner can cool your space.

Choosing the correct BTU rating helps support efficient cooling, quieter operation, and more consistent comfort throughout your RV.

Factors That Affect RV Cooling Needs

The cooling needs of your RV depend on interior square footage, insulation quality, climate zone, ducted vs. non‑ducted airflow, and your available power sources, all of which influence how effectively an RV air conditioner keeps you comfortable.

RV Size & Interior Layout

One of the biggest factors is your RV’s interior square footage. Larger spaces require more cooling capacity, especially if your RV has slide-outs or open floor plans that allow cool air to spread over a wider area.

Travel trailers, 5th wheels, and motorhomes all vary significantly in layout, even at similar lengths. Measuring interior living space gives a more accurate starting point than length alone.

Climate & Sun Exposure

Where and how you camp matters. RVs used primarily in hot, humid regions or parked in direct sunlight will need more cooling capacity than those used in mild climates or shaded campgrounds.

Insulation & Construction

Well-insulated walls, ceilings, and windows help keep cool air inside. Older RVs or models with minimal insulation may require a higher BTU rooftop air conditioner to maintain comfortable temperatures.

Ducted vs. Non-Ducted Systems

Ducted rooftop air conditioners distribute cool air through ceiling vents, helping cool multiple areas more evenly. Non-ducted systems blow air directly into the living space below the unit. Both can be effective when properly matched to the RV size and layout.

Available Power

RV AC units rely on shore power, generators, or inverters. Systems that operate efficiently across varying power conditions can be easier for first-time RV owners to manage, especially when camping off-grid or at sites with limited electrical service.

How to Calculate the Right RV AC Size

To calculate the right RV air conditioner size, estimate your RV’s interior square footage, consider your typical climate, and use BTU guidelines — smaller RVs need lower BTU units while larger or hotter environments require higher BTUs or multiple units.

RV Air Conditioner Sizing Chart

RV Interior Size	Recommended BTU Range	Common RV Types
Under 200 sq. ft.	8,000–13,500 BTU	Small travel trailers
200–350 sq. ft.	13,500–18,000 BTU	Mid-size travel trailers, 5th wheels
Over 350 sq. ft.	18,000+ BTU or dual units	Large 5th wheels, motorhomes

If you frequently camp in hot climates or your RV has limited insulation, sizing toward the higher end of the range can help maintain comfort.

Why Variable Speed Matters in an RV Air Conditioner

Traditional rooftop AC units often operate in an on-off cycle, running at full power and then shutting down once a set temperature is reached. While effective, this approach can create temperature swings, increased noise, and higher energy use.

Variable-speed RV air conditioners adjust their output based on cooling demand. Instead of constantly starting and stopping, they run more steadily, which can support:

More consistent interior temperatures
Reduced noise levels during operation
Improved energy efficiency over time
Better humidity management

For RV owners, variable-speed technology can make RV air conditioning feel more predictable and comfortable, especially during long summer trips.

Furrion Chill Cube RV AC installed on a fifth wheel in Death Valley, California

A Closer Look at the Furrion Chill Cube

The Furrion Chill Cube RV air conditioner is designed for both replacement upgrades and new installations across travel trailers, 5th wheels, and motorhomes. Available in 18,000 BTU configurations, it offers ample cooling capacity for medium to large RVs while using variable-speed technology to adapt to changing conditions.

Key features include:

Variable-speed compressor that adjusts output to match cooling demand
Efficient cooling performance designed to support consistent comfort
Quieter operation compared to traditional on-off cycling systems
Compatibility with ducted and non-ducted rooftop installations
Designed to fit standard rooftop openings, making it suitable for many RVs

Paired with the appropriate air distribution box, the Chill Cube can help deliver even airflow throughout the RV while maintaining a streamlined rooftop air conditioner setup.

Choosing the Right Setup for Your RV

Before selecting an RV air conditioner, consider the following checklist:

Measure your RV’s interior square footage
Identify typical camping climates and seasons
Confirm whether your RV uses a ducted or non-ducted system
Review available power sources and electrical capacity
Match BTU recommendations to your RV size and usage

Taking time to assess these details can help you avoid common sizing mistakes and choose an AC unit that fits your needs.

Frequently Asked Questions

What size AC do I need for my RV?

The right size depends on your RV’s interior square footage, insulation, and climate. Most travel trailers and smaller RVs fall between 13,500 and 18,000 BTUs, while larger RVs may require higher capacity or multiple units.

Is a higher BTU RV air conditioner always better?

Not necessarily. An oversized unit may cycle too frequently, leading to uneven temperatures and reduced efficiency. Proper sizing supports better comfort and airflow.

How do I know if I need a ducted or non-ducted rooftop air conditioner?

Ducted systems distribute air through ducts and multiple vents, while non-ducted units cool the area directly below the AC through a single vent. Your RV’s existing setup typically determines which option is best.

Can one rooftop AC unit cool an entire motorhome?

In smaller motorhomes, one properly sized unit may be sufficient. Larger motorhomes often benefit from dual RV AC units to maintain even cooling throughout the space.

What does BTU mean in RV air conditioning?

BTU stands for British Thermal Unit. It measures how much heat an air conditioner can remove from the air per hour and helps determine cooling capacity.

Are variable-speed RV AC units quieter?

Variable-speed systems tend to run more steadily, which can reduce the sudden noise associated with frequent start-stop cycles.

Find the Right RV Air Conditioner Size for Your Adventures

Understanding what size AC you need for your RV helps create a more comfortable and enjoyable experience on the road. By factoring in RV size, climate, insulation, and airflow, you can choose a rooftop air conditioner that supports efficient cooling and consistent comfort.

If you’re exploring modern RV AC units, variable-speed options like the Furrion Chill Cube offer a flexible solution for both upgrades and new installations, helping you stay cool wherever your travels take you.