Portable AC Energy Consumption and Running Costs Explained

Josh Mitchell

Written By

Josh Mitchell

Expert Reviewed By

Holly Curell

Last Updated On

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How much electricity does a portable AC use? This question is flooding my inbox more than the latest group chat memes.

It's a valid concern–who wants a refreshing breeze that dents your wallet?

I dug to see if these portable units are energy-guzzlers or wallet-friendly.

It turns out that several factors, like the AC's efficiency rating, room size, and even the outdoor temperature, all play a role in power consumption.

At the core, though, is the cooling capacity, measured in BTUs (British Thermal Units).

I uncovered some interesting findings after diving deep into various models and number-crunching.

Key Takeaways

  • The energy consumptions of a portable AC largely depends upon its BTU capacity and energy efficiency rating.
  • Portable ACs can in range BTU from 5,000 to 15,000 which translates to 1.4 kWh - 4.4 kWh in electricity consumption and about $174 - $1,210 running costs respectively. 
  • Units with higher energy rating use lower watts per BTU, but they have a higher upfront cost.

Electricity Consumption is Measured in kWh

Most electric appliances I've reviewed meter their electricity consumption in kilowatt hour (kWh) rather than just watts (W).

This metric represents the total energy an appliance uses in an hour.

For example, a portable air conditioner drawing 1400 watts per hour uses 1.4 kWh (1400 watts x 1 hour / 1000).

Knowing the kWh consumption helps calculate the electricity cost of running a portable air conditioner, considering a specific electricity rate (determined by where you live).

How Much Electricity Does a Portable Air Conditioner Use?

How much electricity a portable AC unit uses depends on diverse specifications, notably BTU ratings.

BTU (British Thermal Units) measures an air conditioner's energy usage, determining its cooling capacity within an hour.[1]

Portable air conditioners with unique specifications highlight the significant BTU rating in their models.

The initially overwhelming BTU discussions captivated my attention in my exploration of portable air conditioners.

Amidst my research, I was intrigued by the direct link between a unit's BTU rating and estimated electricity use (kWh).

I made a table illustrating this connection, including the yearly electricity cost for operating the unit.

Portable AC Unit (BTU)

Estimated Electricity Use (kWh)

Cost Per Year (approx.)

5000 BTU

1.4 kWh


8000 BTU

2.3 kWh


10000 BTU

2.9 kWh


12000 BTU

3.5 kWh


15000 BTU

4.4 kWh


TL;DR: The main property that determines the energy consumption is the BTU rating of your portable AC. 

EER / SEER Ratings and Its Impact on Electricity Consumption

Efficiency matters in a portable unit, and the overlooked factor is its efficiency rating.

Two key ratings for energy costs are EER (Energy Efficiency Ratio) and SEER (Seasonal Energy Efficiency Ratio).

My first-hand lesson came when I replaced my AC unit without checking the specs, leading to a noticeable spike in my electric bill.

What are EER and SEER?

EER measures cooling efficiency per watt-hour used, determining operating costs.

Higher EERs signify better efficiency and lower long-term operating costs.[2]

SEER is more detailed–it factors temperature variations over an entire cooling season.

A higher SEER in a portable air conditioner denotes better energy efficiency.

The US Department of Energy recommends a minimum SEER of 14 for northern and 15 for southern regions.[3]

TL;DR: EER and SEER are two important metrics that determine how efficient the unit is. Units with higher EER and SEER consume lower electricity, but they have a higher upfront cost.

How to Calculate Your Portable AC's Wattage Using EER

Calculating the average consumption for portable ACs was easier than I thought. All I did was use the EER efficiency rating.

Let me do the math: A portable AC's wattage equals the BTU cooling capacity divided by the EER rating.

Average Cooling Wattage = BTU (Cooling capacity) / EER Rating (Cooling efficiency)

A portable AC's wattage hinges on just two factors. Let's walk through an example: a 12,000 BTU unit with an EER of 14.

12,000 BTU / 14 EER = 857 watts used while cooling

The portable air conditioners I tested required 857 watts to deliver 12,000 BTUs of cooling power.

How Much Does it Cost to Run a Portable AC?

Besides kWh, BTUs, efficiency ratings, and wattages, I still had to figure out the cost of running a portable air conditioner.

Previously, I sketched out how a portable AC's BTU and efficiency affect hourly power consumption (kWh).

Here's the missing piece:

Multiply the portable air conditioner's maximum power by your local electricity cost per kWh.

Cost Per House = (Power Consumption in Watts / 1000) x Electricity Rate per Kilowatt Hour

To determine the daily expense, multiply the earlier findings by 8 operating hours of daily portable AC use across common BTU ratings.

The table below demonstrates the approximate expenses for different portable AC units:

Portable AC (BTU)

Power Consumption (Wattages)

Cost per hour ($)

Cost ($)
(8 hours)

Monthly Cost ($)
(28 days)

Cost ($) 
(12 months)

5000 BTU






8000 BTU






10,000 BTU






12,000 BTU






15,000 BTU






In my calculations, I used an assumed electricity cost of $0.11 per kWh for my area. The average price for your location may be different.

TL;DR: The exact cost of running portable AC depends upon the energy unit (kWh) cost in your area multiplied by the kWh consumed.

Factors That Can Impact Electricity Consumption

Before investing in a home portable AC, ponder: How well can it cool, and what's the impact on my electricity bills?

Apart from the AC's cooling prowess, I would look at its operational cost and efficiency. When scouting for a portable AC, I used these pointers to find the perfect fit:

The Size of the Space That Needs Cooling

Like using a single ice cube for a tall glass, what's enough for a small room won't cut it for a large living room.

For a big single room, extra compressor workload and longer AC run times are necessary for effective cooling.

Note that most portable units shine in spaces around 300 to 500 square feet.

Exceeding that means more frequent AC cycles, leading to increased energy consumed (energy waste).

I'd align my portable air conditioner with the spaces' cooling demands.


For moderate climates, 20 BTU per square is a good general rule of thumb.

The BTUs or Cooling Capacity of the AC

I've touched on this before, but let me delve into BTUs' power impact.

Higher BTU ratings imply more cooling but often result in greater energy consumption. Buying a high-BTU unit for specific needs may lead to overkill.

And after running tests, I made these findings:

Oversized units cycle frequently, wasting energy in smaller spaces. Conversely, low-BTU units ran non-stop in a larger room but consumed more electricity.

The sweet spot is aligning BTU output with room size, around 20 BTUs per square foot.

AC's Efficiency Rating - The Higher the Better

I'd prioritize the efficiency rating when shopping for an energy-efficient portable AC.

Key metrics include EER (Energy Efficiency Ratio) and SEER (Seasonal Energy Efficiency Ratio).

Energy-efficient models boast the highest ratings.

A portable air conditioner with a higher EER or SEER uses less energy for the same BTU cooling output.

And it’s no surprise that Energy Star-certified portables don't waste power.

For example, a model with an EER of 13 demands half the energy of a unit with a 6.5 rating for the same cooling effect.


The higher the energy efficiency rating, the higher would be the upfront cost of the unit.

Regarding electricity costs, if you run a portable air conditioner with an EER of 6.6, it doubles your bills.

Despite the upfront cost, the long-term savings from an efficient model justify the investment.

I opt for units with an EER of at least 10, and I recommend you do the same.

Higher Ambient Temperature Outside Equals higher Energy Consumption

During scorching days, my portable air conditioner labors to cool my entire house.

It's akin to running the LA marathon in 100-degree heat – the more direct sunlight, the more effort required.

Portable ACs wage the same thermal battle.

The temperature difference between the outside and inside forces the unit to work harder to pump out cool air.

In extremes, it may run continuously to reach the desired temperature.

What's the homeowner's takeaway?

Overall efficiency dips and electric bills hit an "all-time" high.

Yet, optimizing BTU capacity and efficiency ratings can curb consumption and can save money in the long run.

The Temperature You Are Running the AC At

I didn't need Arctic-level cooling from all the portable ACs I hands-on reviewed. Unless penguins share your space, here's the scoop:

While you may keep your central air conditioning system set to 72F, setting your portable air conditioner between 75 and 78 degrees Fahrenheit is the sweet spot for energy savings. Going colder spikes actual energy usage significantly.

I'm not suggesting you endure heat, but lowering it by a few degrees still impacts your running costs.

General Airflow, Windows, and Ventilation

I've noticed a rookie mistake: avoid blocking your portable AC's vents with furniture like your couch or bed.

While it's tempting to snuggle near the vent, it disrupts general airflow. Mini-splits offer targeted cooling.


Always keep ventilation ducts open for fluid air circulation, and open windows during the day.

I suggest this because the hot air portable ACs draw needs an escape route.

Trapped hot air forces the cooler to work harder, leading to high electricity consumption and bigger energy bills.

Saving money? Not this way.

TL;DR: There are many factors that impact portable AC's electricity consumption including, the BTU rating, efficiency rating, room size that needs cooling, ambient conditions, the temperatures settings, and the general air flow and ventilation in the room. 

How To Save Up On Running Costs When Running Portable AC

Choose the Right BTU Capacity

I can't stress this enough: the "right" BTU amount depends on specific room dimensions.

Higher BTUs mean an energy-guzzling monster, while too few lead to inefficient cooling.

I suggest 20 BTUs per square foot as a baseline for optimal efficiency.

For example, if your room is 350 square feet, you will require a minimum of 350 x 20 = 7000 BTUs.

Understand SEER and EER Rating

It pays off to geek out on energy metrics for portable AC units. I would focus on EER and SEER ratings before making a purchase.

And, no, I didn’t use complex formulas; simply remember that higher EER and SEER ratings mean less energy consumption.

And that results in less running costs when operating a portable air conditioner.

Choose a Model with Energy Star Certification

Consider Energy Star certifications as the gold standard—a recognition of genius efficiency.

To earn this approval, efficient portable air conditioners undergo rigorous lab tests, ensuring optimal cooling with minimal electricity use.

Think next-level efficiency with features like a programmable timer, smart thermostats, and eco modes, alongside impressive SEER and EER ratings.

Though pricier, units with a blue Energy Star label that I reviewed had stellar efficiency.

Regularly Clean Your AC

Appliance cleaning feels more like routine dental checks—not fun but essential.

Same as changing your car's oil filter, clearing debris from portable AC vents keeps it efficient.

Dust buildup strains motors, forcing the AC to overwork, which spikes energy bills.

I do regular maintenance on my portable AC at least once a month. The DIY fix includes cleaning the air filters and checking the exhaust hose for clogs.

TL;DR: Matching the BTU of the AC with that of the room size, choosing a model with great EER and SEER rating, and regularly performing cleaning of the unit can help reduce energy bills.


Can You Run a Portable AC All Day?

You can run your portable AC all day without danger, but prolonged use may result in inefficiency. Consider energy-efficient central air conditioning systems for better performance.

Are Portable ACs Cheaper to Run Than Window ACs?

Window ACs are cheaper to run due to design efficiency. Portable units combine cooling and exhaust functions, causing leaks that impact efficiency and increase power consumption.

Do Lower Temperature Settings on a Portable AC Increase Electricity Consumption?

Lowering portable AC temperatures increases electricity consumption, as compressors work longer at low settings.

Do Accessories Enhance Energy Efficiency in Portable AC Units?

Accessories like thermostats and timers enhance efficiency. Proper insulation and extra filters also improve performance, reducing overall energy consumption.


  1. https://www.eia.gov/energyexplained/units-and-calculators/british-thermal-units.php
  2. https://www.sciencedirect.com/topics/engineering/energy-efficiency-ratio
  3. https://www.eia.gov/todayinenergy/detail.php?id=40232
  4. https://www.forbes.com/home-improvement/hvac/air-conditioner-size-guide/
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Josh Mitchell


Josh Mitchell
My name is Josh and I am obsessed with home appliances. From portable AC units to heaters and air purifiers, I enjoy testing, learning and using these devices to improve the air quality inside my family home.

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Midea U Shaped Window Air Conditioner

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