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# Calculator | DC to AC Amperage Conversion Run Through an Inverter

So, you’ve got an electrical appliance to run, but no place to plug it in. When you need to run a regular household electrical type device in an area where no regular grid power is available, this calculator will help you figure out what size batteries and power inverter you need!

Welcome to our DC/AC conversion tool (with inverter). This calculator is designed to assist you with power usage amounts, when converting from one power form to another using a DC to AC inverter.

Just enter power numbers in the fields below, and we will do the calculations for you, including typical inefficiencies and all that other techie type stuff you may not care to calculate. If you are not sure of your numbers, have a look at the walkthrough illustrations below when entering numbers.

If you want to size your inverter battery pack, then you first need to figure out the DC amperage you will be pulling out of your battery pack through the inverter. This calculator can assist you in figuring out the DC amp draw through an Inverter, so you can accurately size your inverter battery pack.

##### Enter AC Device Ratings
 AC Voltage VAC AC Amperage Amps AC (enter mAh as .xyz) Wattage 0 Watts DC Voltage 12 V     24 V     36 V     48 V DC Amperage 0 Amps DC

## Walkthrough Example AC Voltage - Many applications will have a range of Input AC voltage. In the US, it can be anywhere from 100-125 VAC. In Europe, it's usually 200-240. For this example, we'll use the US standard of 120 Volts AC. Example AC Amperage - Input Amperage is how much current the application draws from the AC power. This number is usually rated in Amps. If the current is rated in milliamps (mAh) you can convert it to Amps by dividing the number by 1000. For instance, our example application draws 300 milliamps, which is the same as 0.3 Amps. Example Wattage - Wattage is the total amount of power the application uses. It's calculated by multiplying voltage by amperage. Therefore the 120 VAC x 0.3 Amps equals 36 Watts. Example DC Voltage - Output Voltage is rating of your battery system, usually a single 12 volt battery. We use 12.5 volts for 12 volt battery systems. Example DC Amperage - Now we know that our application uses 36 watts of total power. If you take this power from a 12.5 VDC source, then the total amperage required increases to 3.31 Amps, or 3,310 milliamps. Since batteries have a limited capacity, or amp hours, it's important to size a battery large enough to handle the amperage demand for your application.

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48 people commented, Rick Nicholson, Tech, Scott Bell, Larry, and 44 others

• This calculator is almost spot on, it would be best if you could choose either to list amps or watts. Remember you're making this calculator for newbies, so yes I know you can divide watts by 120 (north america) and get the amps, but for newbies, easier if you can enter either.

Reply  •  Ratted article 4  •  February 28, 2019 at 10:54 am
• I have a electric motor 220amp. it does not show how many watts info on the motor. Is there a way to find out how many 12volt

Reply  •  Ratted article 5  •  November 28, 2018 at 10:19 am
• Volts x Amps = Watts - If your looking for the wattage you can use this calculation. If this is an AC powered device you can input your AC voltage and Amperage into the calculator above to get both your wattage and DC Amps.

Reply  •  Ratted article 5  •  November 30, 2018 at 8:57 am
• nice handy calucator for inverters Thanks so much

Reply  •  July 19, 2016 at 4:11 pm
• It is hot in Houston. I have a 2000 Btu air conditioning with a power consumption of 270 watts and a nominal current of 2.9A plus a starting current at 13.9A while attempting to use 12vdc battery. What wattage inverter do I need? And how long do you think a car battery will last using the above setup?

Reply  •  Ratted article 2  •  July 4, 2016 at 6:38 am
• At 120VAC @ 2.9 amps your are drawing approximately 32 Amps a hour out of a battery. You would be lucky if a car battery could take that draw for even an hour before excessively discharging the battery. I would use our Calculator | Sizing a 12 Volt Battery to a Load, and just be sure to put in the DC amp draw of 32 Amps, and not the AC amp draw. As far as what inverter to purchase… You need to account for your surge draw which you state is 13.9 amps… 120VAC x 13.9 Amps = 1,668 Watts! The inverter you select must be able to handle that draw, and you might want to talk to the manufacturer to see how long that surge lasts. Most inverters come with a surge rating for less than a second, so if your surge last longer it generally forces you into a larger inverter.

Reply  •  January 25, 2017 at 7:50 am
• ls I have a DC appliances that’s uses -48v and the current in my region is an AC with 200v – 220v, how do I get an accurate result?

Reply  •  Ratted article 5  •  July 4, 2016 at 1:59 am
• If your device runs off 48 volts then there is no need to be looking for an inverter. Your device is meant to run off either a 48v power-supply, or a 48v battery pack.

Reply  •  January 25, 2017 at 7:19 am
• i have a 5000 watt invertor fitted to my nissan patrol ute .
so how many 12volt batteries would i need to get max 240 volt power out of the invertor ???????

Reply  •  Ratted article 1  •  June 30, 2016 at 5:01 am
• As you can see by the calculator that would draw about 460 Amps an hour out of a 12v battery pack! Next I would suggest using our Calculator | Sizing a 12 Volt Battery to a Load, as it depends on how long you want to run that load for…

Reply  •  January 19, 2017 at 10:28 am
• amazing useful

Reply  •  Ratted article 5  •  May 4, 2016 at 1:50 am
• This tool was helpful. Just a quick question. I guilt a solar generator with a 100 watt panel, a 12V inverter that puts out 220 VAC and a 12 V battery. It is supposed to run a stock well that is 480 Amps. With just one battery it only runs 3 minutes the overloads the battery. If I read the calculator right this pump will draw 9715.20 Amps DC, but each 12 V battery will only put out 3,310 milliamps. So if I connect 3 12 V batteries in parallel, will that be sufficient to run this pump or should I connect 4 12 V Batteries?

Reply  •  April 20, 2016 at 9:19 pm
• Now that you used this calculator to determine what you will be drawing out of the battery. I would suggest using our Calculator | Sizing a 12 Volt Battery to a Load. This calculator will tell you what size battery pack you need to create depending on how long you want to run the well for.

Reply  •  Ratted article 5  •  April 21, 2016 at 12:03 pm
• Can I use this in reverse? I have a 100A 240V sevvice but need to power a DC rectifier shelf that is capable of 200A. If I use this calculator and input 100A AC, 240VAC, 48VDC then the calculator shows 552A DC. DOes this mean that the 100A AC service can supply up to 552A DC?

Reply  •  October 31, 2014 at 11:53 am
• In reverse it would be a charger vs an inverter, however if the charger runs off 240VAC and draws a 100A then it will put out approximately 552A on a 48V system, but it might vary depending on the efficiency of the charger.

Reply  •  Ratted article 5  •  November 19, 2014 at 10:23 am
• I have a portable 5000 BTU air conditioner unit. The tag shows that it uses 504 watts and 4.5 to 4.8 Amps. It runs very well with a 1200 watt generator. How long can it run using an inverter, a 100 amp hour AGM battery rated at 1200 watts?

Reply  •  Ratted article 5  •  September 11, 2014 at 9:19 am
• 504 watts / 4.8 Amps = 105 VAC. This would pull 46.37 Amps DC, so you could run about an hour before you start to excessively discharge the battery.

Reply  •  Ratted article 5  •  September 25, 2014 at 10:18 am
• Great tool.

If you add inverter efficency as an optional input that might be good as well.

Reply  •  Ratted article 5  •  September 6, 2014 at 4:51 am
• Glad to help! I will send your recommendation up the food chain and see if we can make it happen!

Reply  •  September 12, 2014 at 1:07 pm
• Thanks, this was very helpful, but mainly to give me an idea of the current draw on the batteries so that I can work out what circuit breaker/fuse to get.

Reply  •  August 26, 2014 at 4:13 am
• Either the multi-meter is hooked up backwards, or you have forced the batteries to charge backwards. Usually you are reading the reverse terminals.

Reply  •  August 22, 2014 at 9:45 am
• hi,
why do we hav some devices taking negative voltage?
e.g BTS operates in -48V (DC)

Reply  •  August 21, 2014 at 5:14 am
• Due to the fact that we don’t have all the information for your system we would need you to contact us at tech@batterystuff.com so that we can ask the appropriate questions, to get you the answer that you may need.

Reply  •  August 15, 2014 at 2:25 pm
• Good morning.
I have calculated that I need 300 Amps DC per day.
How many 250 watt 12 volt solar panels do I need to keep up with this demand.
My battery bank is 3000Ahs 12 volts.
Regards
Bill

Reply  •  August 13, 2014 at 11:30 am
• This is GREAT stuff.
Thank you ALL for the info.

Reply  •  Ratted article 5  •  August 12, 2014 at 10:07 pm
• I have a 24VDC power bay with a DC to DC convertor (-48VDC). If I’m reading 30amps on -48VDC side how much power is my 24VDC bay actually providing?

Reply  •  June 23, 2014 at 2:52 pm
• That depends on the efficiency of the converter. On the 48 volt side, you are using essentially 1450 watts. The wattage on the other side, the 24v side, will depend on the efficiency of the conversion process.

Reply  •  June 25, 2014 at 9:05 am
• Hi tbere i am looking to no how long my 240 appliances will last for with 2 110 batteries working of a 1500watt inverter drawing 980watts in total a total of 88 odd amps of dc how long will my batteries last and what size of solar panel would suit to maintain my batteries as i have only a splitt relay wired as a charging system

Reply  •  Ratted article 5  •  June 17, 2014 at 9:01 pm
• 240VAC doesn’t change the total power of the system. The same calculations will work. In your case, you will get roughly an hour 1/2 of run time.

Reply  •  June 20, 2014 at 11:55 am
• i wish to power a series of appliances whose total sum of wattage is 720 watts for a minimum of 3 hrs non stop. i have already purchased a 12v – 220v inverter which is rated 1500watts…my questions aer: what rating of one 12v battery (or a system of combined batteries) do i need to achieve this target.Also , what specification of solar panel charging system can charge the battery in a very short time like 2 hours of sunlight…we do have intense sunlight in my region.

thanks

Reply  •  Ratted article 5  •  May 26, 2014 at 6:41 am

Reply  •  May 27, 2014 at 9:45 am
• Would this calculator also work if I wanted to know what a switch that was rated AC would handle in DC?

Reply  •  Ratted article 5  •  June 17, 2013 at 11:36 am
• Jordan, this calculator is a simple AC to DC conversion. It will not work for your situation. Thanks

Reply  •  May 21, 2014 at 12:35 pm
• Ok I used your tool above (THANK YOU SO MUCH FOR THIS TOOL) to determine the battery I will require to run my 5V 2A device from a 12volt battery. The tool returned .92amp DC. So my question is how can I now determine what size battery in amp hours I require to run this device for 10 hours?

Reply  •  April 11, 2013 at 9:05 am

Reply  •  April 12, 2013 at 7:49 am
• DC to AC amperage conversion run through an Inverter.
What is the correct explanation of why requires 5 DC amps per each AC amp?

Reply  •  April 4, 2013 at 7:11 am
• Amperage is the flow of electricity, while voltage is the pressure. Saying that it requires 5amps DC to 1 amp AC is not a correct statement. What is true is that in a 13volt (12 volt nominal) DC system, ran through an inverter that is about 80% efficient, the total power useage is approximently 78 watts, which would be a little under 1 amp at 115VAC. Wattage is the total power, which is comprised of voltage * amperage. If you change the voltage, but leave the wattage (total power) the same, then the amperage has to change as well.

Reply  •  April 4, 2013 at 9:21 am
• nice tool thanks for your information .can you explain about %loss calculation

Reply  •  March 19, 2013 at 3:43 am
• The loss figured is based upon the average efficiency for Pure Sine Wave power inverters. In this case, 15% loss, or 85% efficiency.

Reply  •  March 19, 2013 at 10:31 am
• span class="caps">VERY NICE TOOL.

Reply  •  February 27, 2013 at 2:50 am
• When talking about current, for example if a device is drawing 3 amps, does that mean 3amps per hour?
So if your drawing 3 amps from a 3amp/hour battery, that battery would last about 1 hour? Right?

Reply  •  Ratted article 4  •  February 4, 2013 at 12:04 pm
• Nice tool
Thanks

Reply  •  Ratted article 5  •  November 28, 2012 at 8:20 am
• Nice tool!
Thanks
Good idea to add the % of losses too!

Reply  •  November 24, 2012 at 4:30 am
• This was exactly what I was looking for. I would like to have the formula though just in case I need to do it the old fashioned way.

Reply  •  October 31, 2012 at 2:47 pm
• The calculator uses Ohm‘s Law. Watts = Volts x Amps. We additionally take into consideration an average inefficiency rate of 15% because the power is passing through an inverter. Once you find the watt amount from the AC volts x amps, you can divide the watts by DC volts to get DC amps, plus 15%. Without the efficiency loss, AC or DC watts will always be the same because it is total power. But as voltage goes up or down, in order to have the same power the amps will adjust accordingly.

Reply  •  October 31, 2012 at 3:09 pm
• Very useful. But I believe Watts = Volts x Amps is Watts law. Not Ohms law.

Reply  •  Ratted article 5  •  May 19, 2014 at 2:12 pm
• Dave, that is correct. Thanks for the correction. Ohm’s law is V=I*R, Watt’s law is W=V*I, where V=voltage, I= current, R= Resistance, W= Wattage.

Reply  •  May 21, 2014 at 12:48 pm 