Trying to work out what size inverter you need?
If you purchase an inverter without enough power, you won’t be able to run all your appliances, tools, and gadgets.
On the other hand, there’s no point in going too big as it will be unnecessarily expensive.
Plus, if you draw a lot of power with a huge inverter from a small battery, you’re going to run out of electricity fast.
That’s why I’ve put together a handy inverter size chart in order for you to quickly find out what size inverter is best for your needs.
We’ll start by going through the basic considerations, use a size chat to identify the best inverter, and work out your personal power consumption.
Let’s go!
What Size Inverter Do I Need?
It’s actually very easy to work out what size inverter you need.
It all comes back to when appliances and electronics you want to run.
In simple terms, all you need to do is use an inverter with a higher power capacity than the total amount of your appliances.
Power capacity is measured in watts (W). That’s useful as inverter size is labeled in wattage too. When you’re browning products you’ll quickly see they have 200W, 300W, 1000W, 3000W, etc, listed.
To find out your size, you just need to add together the total wattage of the appliances you wish to run.
For example, TV (60W), coffee maker (700W), lamp (60W), phone (5W). So add together 60 + 700 + 60 + 5 = 825W.
Now we know the inverter must be larger than 825W.
Inverter Efficiency
It’s important to always use an inverter with a larger capacity than your required power. This is because they are not completely efficient as they lose energy during the DC to AC conversion, plus require energy for internal systems.
Often inverters are between 85% and 95% efficient.
So you should factor this into your final number. I like to add a safety net of 20% for efficiency.
To include this just multiple your appliance watts by 1.2.
So for the example above: 825 x 1.2 = 990W. My inverter should be a minimum of 990 watts. In this case, I’d choose a 1000W inverter.
To sum up: Add wattage of appliances together then multiply by 1.2
Keep reading in order to find out how to find the wattage of any electronics or appliance
Inverter Size Chart
To help you quickly find your inverter size, I have created this easy-to-read inverter size chart. The watt rating of each appliance is a general average for you to compare against inverter sizes.
How to Work Out Wattage
The size chart above it offers the average power of common appliances. It is a good idea to work out an accurate wattage of your own appliances.
There are a few simple ways to do this.
Product Information
The quickest way is to check the product technical information or user manual. Quite of the wattage is clearly listed.
For example, I quickly found the information from the sticker on my heater:
Wattmeter
You could also use a wattmeter. These are brilliant little devices to hook up to your electronics for a live power reading!
Calculate Wattage
Finally, you can always do some quick maths.
To work out Watts you need to multiply Volts by Amps. The formula is:
Volts x Amps = Watts.
For example, 120V x 2A = 240W.
Continuous vs Peak Wattage
When looking at inverters you’ll also see two different wattage ratings – continuous and peak.
Continuous wattage is the most important number to consider as this is the power the inverter can deliver for a prolonged period of time.
Peak wattage is designed so an inverter can cope with surges in power for a few seconds. It won’t last more than 5 to 10 seconds. You usually get a quick surge in power when switching on appliances particularly if it has an inductive load like microwaves and compressors. Usually, peak wattage is double continuous wattage.
Match Your Inverter Voltage
One final thing to check is the inverter voltage (V). You must match the inverter input voltage to your battery voltage. The most common size is a 12V inverter with a 12V battery. You can also get 24V and 48V options.
If you try to use an inverter with a higher voltage than your battery it will lead to undervoltage and won’t work. If you use an inverter with a lower voltage than your battery it will lead to overvoltage and won’t work.
Is a Bigger Inverter Better?
As we discussed above, it is always better to use an inverter with a bigger capacity than your appliance’s needs.
If you want to draw 500 watts, a 500 watt inverter will not be big enough as they are not 100% efficient. So in this respect, bigger is better.
From a less specific point of view, just buying the largest inverter available is not always the best option. There’s no point in using a 3000W inverter for a 500W load, it’s overkill and going to be very expensive for your needs.
Adding to this, remember to think about your battery size. Sure you might want to draw 5000W of power to run your whole house but if you only have one small battery then you’re going to run out of energy fast. I suggest you read my guide on ‘How Long Will a Battery Power an Inverter’ to understand this.
What Sizes Do Inverters Come In?
You can get inverters in a wide range of sizes ranging between 50 watts up to 50,000 watts.
For the normal consumer, you will be able to choose between 50 watts to 5000 watts. Anything more than this is reserved for more commercial uses. Most inverters under 200 watts are designed to be used in cars while more powerful options are brilliant for homes, RV, semi-trucks, and solar panels.
Final Words on What Size Inverter Do I Need?
If you’ve read this far you should now understand how to work out what size inverter you need.
By following the advice above and using the inverter size chart you can pick a product knowing it will be able to run all your appliances.
Take the time to add up the total wattage of all your appliances before making a purchase. And remember to size your inverter based on continuous wattage that is bigger than the load you want to draw.
