Off-the-Grid: How Many Watts Does a Refrigerator Use?
Refrigerators and freezers are used for preserving the food, cooling down beverages, and for other similar tasks. When the mains power is gone, refrigerators and freezers stop, with all the stored food and drinks being in jeopardy.
Regardless if You have a fridge that you want to keep operational during a power outage or you want to have a fridge or freezer running when camping, it is vital to know the power and energy requirements of your unit.
Updated: July 24, 2023.
On This Page:
Refrigerator/Freezer Power: Starting vs. Running Watts
Refrigerators and freezers are powered by electric motors that require more power when starting (hence 'starting watts').
Actual power requirements differ greatly depending on the refrigerator/freezer size, energy class, temperature difference, etc.
Older larger units require up to 700-1000 running watts and 2000-3000 watts when starting.
If You have a large home refrigerator/freezer that requires 500+ watts, check its energy star rating - buying a new, energy more efficient unit may lead to great energy (and money) saving over a certain period of time.
We say 'certain period of time' since this period depends on local electric energy prices, the power difference between units, etc.
The power consumption of a modern refrigerator/freezer varies:
- large home refrigerator: 200-400 running watts, 1000-1200 starting watts,
- average home refrigerator: 100-250 running watts, 700-1000 starting watts,
- small home refrigerator: 75-150 running watts, 400-600 starting watts,
- compact home/RV refrigerators: 40-50 running watts, 80-120 starting watts.
Note: the best method of finding out the actual power requirements of your unit is to locate and check a small plate on the back of the unit with its power requirements.
How Many Amps Does A Refrigerator Use?
Most refrigerators and freezers in the US are powered by 120V AC. That means that in order to get actual Amps, we have to divide the required Watts by Volts:
I (A) = P(W) / U(V)
Note: we assume the phase angle to be zero.
Thus, we get:
- large home refrigerator: 1.66-3.33 Amps cont., 8.33-10 Amps when starting,
- average home refrigerator: 0.833-2.1 Amps cont., 5.83-8.33 Amps when starting,
- small home refrigerator: 0.625-1.25 Amps cont., 3.33-5 Amps when starting,
- compact home/RV refrigerators: 0.33-0.42 Amps cont., 0.66-1 Amps when starting.
For example, if we have a 200/800W 120V AC refrigerator, then its continuous and starting currents are:
Icont(A) = 200W / 120V = 1.666 A
Istart(A) = 800W / 120V = 6.666 A
Thus the fridges and similar appliances are connected to 15 Amps or preferably to 20 Amps electric circuits, especially when combined with other loads.
Similarly, when the refrigerator is run by 12V or 24V DC, the calculation is very similar.
For example, a 50/100W refrigerator is run by 12V DC, which means that:
Icont(A) = P(W) / U(V) = 50W / 12V = 4.166 Amps
Istart(A) = P(W) / U(V) = 100W / 12V = 8.333 Amps
That means that the fridge in this example draws ~4.2 Amps @12V continuously, but also 8.333 Amps when starting.
What Is A Refrigerator's Duty Cycle?
Refrigerators and freezers are not working constantly - electric motors that power their compressors are turned On and Off, with an On period depending on many things, including room temperature, units' energy class, how often the fridge is being open, etc.
On average, a refrigerator's duty cycle is 30-40% (on average ~35%), while a freezer's duty cycle is ~65%. This means that the refrigerator's motor runs ~35% of the time, and the freezer's motor runs ~65% of the time.
This is very important when dimensioning power stations and power generators required to provide power in off-the-grid situations for such units.
Estimate Your Refrigerator's Energy Consumption and Cost
Now that we know the power (Watts) of the refrigerator, it is rather simple to find out the required energy (in theory) for different types of refrigerators and the cost of the energy.
So, if we have:
- large home 300W refrigerator requires 300Wh per hour of energy.
If 1 kWh costs 0.15 $US, then the running of that refrigerator costs ~0.045 $US per hour or ~1.08 $US per day, not taking "Duty Cycle" into account. When taking 35% duty cycle into account, running such a refrigerator actually costs ~0.38 $US per day.
- average home 150W refrigerator requires 150Wh per hour of energy.
If 1 kWh costs 0.15 $US, then the running of that refrigerator costs ~0.0225 $US per hour or ~0.54 $US per day max.; with a 35% duty cycle, running that refrigerator costs ~0.19 $US per day.
- small home 100W refrigerator requires 100Wh per hour of energy.
If 1 kWh costs 0.15 $US, then the running of that refrigerator costs ~0.015 $US per hour or ~0.36 $US per day max.; with a 35% duty cycle, running that refrigerator costs ~0.13 $US per day.
- compact home/RV 50W refrigerator requires 50Wh per hour of energy.
If 1 kWh costs 0.15 $US, then the running of that refrigerator costs ~0.0075 $US per hour or ~0.18 $US per day max.; with a 35% duty cycle, running that refrigerator costs ~0.07 $US per day.
Note: These values are given for the average cost of electricity of 0.15 $US.
Off-the-Grid: How to Power Refrigerator/Freezer
There are several ways of powering refrigerators during emergencies and power outages.
These include portable power stations, deep-cycle batteries combined with power inverters, and by using portable power generators.
Power stations are the most convenient, but they store the least energy. Deep cycle batteries are able to store much more energy than the batteries found in the power stations, allowing them to power refrigerators and other appliances for a longer period of time.
In the end, power generators, especially portable power inverter generators, convert chemical energy into electric energy, providing the longest runtime of them all - practically as long as fuel is available.
Portable Power Stations
Portable power stations feature built-in lithium batteries and power inverters and often come with 1-2 110V AC ports, combined with USB charging ports.
Depending on the size and energy class of the refrigerator, a 500W portable power station that stores at least 500Wh of energy is enough to power a 250W home fridge (or any similar device) for up to 1h and 35 minutes, while a 1000W portable power station with 1000Wh of stored energy can power 250W appliance up to 3 hours easily.
Note: Power stations usually feature an efficiency of ~80%, but are practically always advertised using 'raw' energy stored in the built-in battery.
Also, depending on the fridge's use and temperature difference, its electric motor may operate constantly, but also On/Off with the Off period being often much longer than the On period - in that case, such portable power stations may power such appliances for much longer periods of time.
Example:
One of the most popular power stations on the market is Jackery 1000, which is able to store ~1000Wh of energy and features an energy efficiency of ~85%.
So, if we are going to power an average home 150W refrigerator using Jackery 1000, one may expect a runtime of:
T(h) = 0.85 * 1000 Wh / 150 W = ~5.6 h
when the unit's "Duty Cycle" is not taken into account. With a 35% duty cycle, such a power station can power such a fridge for up to 16(!) hours, and when the power station is combined with solar panels (with at least a partially clear sky), such a power station can practically power 150W refrigerator indefinitely.
Also, a great feature of power stations is that they don't release dangerous fumes and can operate indoors.
| /td> |
Deep Cycle Battery & Power Inverter
Another similar solution is using large deep-cycle batteries (AGM, Gel-Cell, wet/flooded, lithium-ion, etc.) and the power inverter.
Depending on the size of the battery (or battery pack) and the output power of the power inverter, such combinations may be used to power several home appliances for longer.
For example, 2x 200Ah 12V batteries connected in series (24 volts), with 1000W pure sine wave power inverter with 85% efficiency, are able to power 250W refrigerator for 14-16 hours constantly - if we assume that the batteries don't suffer from the capacity loss due to the large(r) discharge current (lithium batteries, for example), the exact runtime would be:
T(h) = 0.85 * 2 * 200Ah * 12V / 250W = ~16.3 h
When a 35% Duty Cycle is taken into account, the actual runtime is ~46 hours, which is almost two days!
Also, a great feature of the power inverter & deep cycle battery combinations is that they don't release dangerous fumes and can operate indoors, just like power stations.
Portable Power Generators
Another solution that stores energy in the form of fossil fuel are portable power generators.
Note: Portable power generators MUST NOT be used indoors since they emit dangerous and toxic fumes.
The most popular class of portable power generators are 2000W power generators. Most of these units can operate at 25% power (400-500 watts) for up to 10-12 hours, which is equivalent to 4-6 kilowatt-hours of energy.
During this period, the 2000W power generator operating at 25% (500W) can power 250 watts refrigerator constantly and charge a 12V battery (or battery pack) with ~15-17 Amps.
Again, portable power generators release carbon monoxide and other fumes that can kill humans and animals easily. This is a serious warning - never operate a power generator indoors!
Many people wonder about the costs of running such units. The costs of running these units consist of fuel, maintenance, and the unit itself.
When the mains power is available, power generators are simply too expensive to operate. However, in emergencies and blackouts, additional costs are of no issue.
On average, power generators powered by four-stroke engines require 0.15-0.3 gallons of fuel per 1 kWh of energy when they operate at 50-100% load. Also, power generators powered by two-stroke engines require 0.3-0.45 gallons of fuel per 1 kWh of energy when they operate at 50-100% load.
Most power generators, especially those whose power is measured in kilowatts, are based on four-stroke engines.
When the load is decreased, the energy efficiency of the power generators drops.
Hence, it is a good practice to power several tools and appliances, battery charger for deep cycle batteries included, when the power generator runs.
And when it is turned off, let the deep cycle batteries do their own job via a power inverter - of course, if such a setup is available.
For example, if we are powering a 200W refrigerator using a power generator that also powers other appliances and it consumes 0.2 gallons of fuel per 1 kWh, then the power generator consumes 0.04 gallons of fuel per 200 Wh required for the refrigerator for one hour of operation - other 0.16 gallons of fuel and 800Wh of energy are gone for other appliances - in this example, we are interested only in the fridge.
If the price of fuel is 3.5 $US per gallon, then the cost of fuel for running this 200W refrigerator is 0.14 $US per hour or 3.36 $US per day, which is much more than running the fridge using mains power - and this is just a fuel price, maintenance costs and the cost of power generator are not included.
For more about this topic, feel free to check our Top 70+ Most Fuel Efficient Power Generators article.
Note: this example doesn't take into account the refrigerator's Duty Cycle (motor On/Off) - if the power generator runs when the fridge is not, fuel is wasted. Personally, don't use a power generator to run just a fridge - if you do have a fridge only to run, use your power generator to recharge your power station or deep cycle batteries, and when they are fully recharged, turn the generator Off.
Frequently Asked Questions - FAQ
Here are some of the most common questions we get about powering refrigerators:
How many Amps do fridges draw?
As we said before, current depends on the refrigerator's wattage - modern refrigerator/freezer typically require:
- large home refrigerator: 200-400 running watts, ~1.66-3.33 Amps @120V,
- average home refrigerator: 100-250 running watts, ~0.83-2.1 Amps @120V,
- small home refrigerator: 75-150 running watts, ~0.625-1.25 Amps @120V,
- compact home/RV refrigerators: 40-50 running watts, ~0.33-0.42 Amps @120V.
Similarly, when calculating the required Amps for Starting Watts, just divide the Watts by Volts:
I(Amps) = P(W) / U(V)
If You have a small RV 12V 50W refrigerator, such unit draws:
I(A) = 50W / 12V = 4.16A
If a refrigerator and other appliances draw ~30 Amps from RV's home battery which is a 12V 600Ah battery bank (for example, three (3) lithium 12V 200Ah batteries connected in parallel), such battery bank can power such setup for up to:
T(h) = 600 Ah / 30A = 20h
Note: to simplify the math, we didn't use the Duty Cycle of the refrigerator in this example.
Can I run a refrigerator on a 15 Amps circuit?
Yes, refrigerators generally can run on 15 Amps circuits, especially if they are connected to their dedicated circuits.
How many refrigerators can you have on a 20 Amps circuit?
It all depends on the Running/Starting Watts/Amps.
Generally, the sum of their Starting Amps should be below 16 Amps (taking into account a 20% safety reserve).
Note: some users do this calculation using "Running Watts/Amps" with no safety reserve - sooner or later, refrigerators will start at the same time, causing the electric breaker to trip. Also, wires may be running very warm/hot, potentially causing other issues ...
How long will a 12-volt fridge run on a battery?
12-volt refrigerators generally range from 40 to 100 watts, although there are both smaller and larger units.
A 12-volt refrigerator that features 60 running watts draws on average ~5 Amps from the 12V battery.
If the 12V battery is a large, deep cycle battery with a nominal capacity of, for example, 100Ah, then the runtime is
Time(h) = Capacity (Ah) / Current (A) = 100Ah / 5A = 20h
That means that the refrigerator that draws 5 Amps can constantly operate for 20h when being powered by a 100Ah battery.
If the refrigerator is in a cool area and not exposed to direct sunlight, and not opened frequently, its motor will not constantly run while keeping the items in the fridge cool.
This ratio between the motor's active/non-active time can vary, but the actual 20h runtime can be much longer - with a 35% Duty Cycle, the actual runtime of the fridge in the example would be:
T(h) = 20h / 0.35 = 57h
which is almost two and a half days.
What watt generator do I need to run a refrigerator?
Since refrigerators feature electric motors that require plenty of power when starting, the power generator should have its Starting Watts at least the same as the Starting Watts of the refrigerator.
Since this may cause plenty of starting issues, it would be much safer to require the power generator to have maximum Running Watts, at least the same as the Starting Watts of the refrigerator.
Generally, 2000W inverter power generators are strong enough to power refrigerators and a few more appliances.
What size generator do I need to run two refrigerators?
When two refrigerators must be powered using a power generator, find their individual power consumption and sum it up.
For example, if You have:
- Refrigerator 1: 50 Running Watts, 200 Starting Watts,
- Refrigerator 2: 150 Running Watts, 600 Starting Watts.
These two units combined require 200 Running Watts and 800 Starting Watts.
Note: Two units like refrigerators rarely start simultaneously, but it does happen (remember the Murphy Laws!).
In theory, a 1000W power generator is more than enough. However, in order to have a little bit more power reserve (there is always the need to power "one more" device/appliance), go for a 1500-2000W power generator.
Can you run a refrigerator on a regular generator?
Regular power generators have Total Harmonic Distortions (THD) levels in the 15-20% or more range. Since refrigerators feature electric motors, such THD levels should generally not be a problem.
However, modern refrigerators often come with a set of control electronics that may be sensitive to high THD levels.
Thus, if You plan on powering your fridge using a regular power generator, check the documentation that came with the fridge.
Anyway, inverter power generators with very low THD levels (≤3%) are recommended.
How much electricity does a refrigerator use per hour?
Find the required power of your refrigerator (for example, 200W), and calculate the maximum of energy that your fridge requires per hour (in this example, 200Wh).
If the fridge is not open frequently and it is placed away from the heat sources, its motor will not operate constantly, keeping the electric bill smaller - again, on average refrigerators feature ~35% duty cycle.
How much power does a refrigerator pull?
Anywhere from 40-50 watts (small, energy-optimized units) to 700-800 watts of the large, older type of refrigerators.
The most accurate way of finding the required wattage is to find a small metallic plate at the back of your unit and see how many watts it requires. Or, check its manual.
How many Watts of solar power are needed to run a refrigerator?
In order to safely power a 200W refrigerator using solar panels, one needs either:
- power inverter strong enough to provide 200 Running Watts with some extra power for refrigerators Starting Watts, a good deep cycle battery, solar charge controller, and enough solar panels, or,
- strong enough solar power station with enough solar panels.
In both cases, one also needs an efficiency factor of both systems, which is usually in the 75-85% range.
That means that, on average, in order to provide a refrigerator with 200W, solar panels must provide 235-267 watts.
Since the actual output power of solar panels is lower than their nominal power, the nominal power of solar panels required to power a 200W fridge is:
P(nominal) = P(actual)/0.5 = ~470 to 534 watts
However, the refrigerator's motor is not running constantly, especially if the fridge is kept away from the sun and the door is not opened frequently - in that case, the solar panels may be smaller, but how much smaller depends on the details that are beyond the scope of this article.
But, if You have 500W solar panels connected to a high-capacity lithium battery (lead-acid battery is also good, but lithium batteries have better energy efficiency) via a lithium battery solar charger and everything connected to a pure sine wave power inverter, such a system will be able to power not only the fridge 24/7 but several smaller loads as well - everything depends on the sunlight availability, number, power requirement, and energy efficiency of connected devices.
Can a 1500-watt generator run a refrigerator?
Yes, almost all modern refrigerators feature starting watts below 1500 watts, with running watts often well below 500 watts.
Few Final Words
If You wonder how many watts your refrigerator uses, check its label on the back or perhaps the manual.
Modern, highly efficient units often require just a fraction of the power and energy that was required by the units 10-15 years ago.
When the mains power is not present, having a working refrigerator is very important for several reasons, especially if the refrigerator or the freezer is full of food that must be preserved for a longer period of time.
In such situations, a working fridge, combined with a TV and microwave oven, can be a real morale booster and a lifesaver.
