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Knowledge Base : Tools : Calculator | AC to DC Amperage Conversion Calculator using a DC to AC Power Inverter

# Calculator | AC to DC Amperage Conversion Calculator using a DC to AC Power Inverter

Welcome to our AC to DC Amperage conversion calculator! So, you’ve got an electrical household device you need to run but no regular grid power available, right? For this you need a DC to AC Power Inverter that takes the DC voltage a battery provides and inverts it to AC voltage so that you can run an AC Powered Device. (Not to be confused with a converter, which takes AC to a DC.)

The first step to sizing the battery pack when using a DC to AC Power Inverter is to know your DC Amp rating. This calculator helps you determine the DC amperage as it passes through a power inverter. The calculator also provides the wattage rating you are pulling so you can properly size the power inverter you need!

Just enter your AC Voltage and AC Amperage into the fields below and we will do all the hard calculations for you. This calculator includes the typical inefficiencies in efforts to give you realistic DC Amperage Rating.

There is a solar article that goes well in depth on these calculations if you’re interested in the techie type stuff: Solar Info: The Down Low on Everything Up High

##### 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 VAC. For these examples, we'll use the US standard of 120 Volts AC (240 VAC can be entered in the calculator for the inversion). Example AC Amperage - Input Amperage (AH) is how much current the application draws from the AC power. Most applications have this listed on the AC power brick. 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 mAH). 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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65 people commented, TECH, George Harris, Ms Otis, Tech, and 61 others

• I have an oxygen machine that pulls 4.9 amps from 120volts AC. That converts to 588 watts. I want to run it through an inverter in a car. What size fuse would this require and would a well functioning alternator run it for an extended period of time?

Reply  •  Rated article 5  •  January 14, 2023 at 7:43 am

• At 4.9 amps on the AC side, that equates to 54.1 amps on the 12v side. I doubt your cigarette lighter, or any power port can sufficiently handle that amperage. Typically, we recommend getting an auxiliary battery and hardwiring your inverter to that battery. In this setup you would need a battery isolator to care for the starting battery and auxiliary battery, but this is more reliable and doesn't put your starting battery at risk of being discharged. Regarding the alternator, I would suggest reaching out to your vehicle's service department and posing that question to them. You know that your machine will be pulling approximately 55 amps on the DC side, so they should be able to tell you if your alternator has sufficient headroom for that draw or if you need to upgrade and what those upgrade options may be.

Reply  •  Rated article 5  •  January 23, 2023 at 1:57 pm

• rotect freezer against short power outage UK Effect of start up current on small say 8 Ahr SLA 12V battery Say freezer uses 2A but on motor start its 6A for 1 sec or so: l Wil that destroy this small battery: Looks like a battery surge of 130A or so ! But even a larger battery would surely suffer. How do we determine the short time peak current battery can withstand before huge voltage drop ? MsO

Reply  •  Rated article 5  •  October 21, 2022 at 10:10 am

• How a battery will react under various amp loads is typically covered in the specification sheet for the battery issued by the manufacturer. I suggest contacting your battery distributor and asking for a specification sheet or visiting the manufacturer's website, as they sometimes have them available for download. In the end, if the specification sheet doesn't cover that information, I would suggest reaching out to the manufacturer for specific as they may have some information on hand.

Reply  •  Rated article 5  •  December 13, 2022 at 12:25 pm

• Hello, I am working on a vanbuild and I am curious if I would be able to run my water heater(29amp draw) off of my 12v dc-115 ac inverter? The manufacturer recommended setting up a 20 amp plug to attach to the heater wires+ground wire, would it be reasonable to attach the 20 amp plug to a 20-15 amp adapter and run it? Thanks

Reply  •  Rated article 5  •  July 10, 2022 at 5:53 am

• It depends on the size of your inverter, but 29 AC amps is a lot of energy to pull even for a short about of time. Even if the inverter was capable it is probably not likely a battery pack in a van would be able to handle such a load for more than a few minutes before the inverter started to alarm due to the voltage drop. This is why most RV's come with a gas water heater over an electric water heater.

Reply  •  Rated article 5  •  July 14, 2022 at 9:48 am

• I have a 12v car battery and I also have 240v electric motor. So can the 12v battery run the electric motor???

Reply  •  Rated article 2  •  June 3, 2020 at 11:10 pm

• Unfortunately, no. Depending if the motor is an AC or DC motor you would need either inverter or converter to run the motor off of a battery.

Reply  •  Rated article 5  •  June 15, 2020 at 1:46 pm

• What I am about to ask will most likely make you cringe, but with that said. I have a car audio amplifier and subwoofer set up that i can no longer use in my vehicle. It is a 2000 watt amp when connected to a 1 ohm load. The subs play real low, like down to 25hz. Which makes me want to bring this inside for movies. Stupid idea, I know. However, I am still interested in repurposing this setup. The question I am asking is beyond my comprehension, so please be patient. If the amp pulls around 200 amps DC to create 2000 watts at 1 ohm. How does that equate to AC? The standard breaker in my house is 15 amp's, with a few at 20. Is there a power invertor that can plug into a 120 volt outlet and provide the power needed for the amp? Would it require a 220 volt? Would that still not be enough power? Any help will be appreciated. If you need more information, please let me know.

Reply  •  Rated article 5  •  April 28, 2020 at 7:55 am

Reply  •  Rated article 5  •  June 3, 2020 at 12:26 pm

• It’s not entirely stupid, it’ll give you nice sound but depending on your exact setup there may be syncopation effect where the timing is off from the rest of the system, like the site said there may be some trial and error involved, but assuming the 2000w amp is peak draw you may want to search for an inverter with that draw on a single channel. Be warned the cooling fan at that rating is likely to be loud. You could place a car audio capacitor inline between the inverter and the amp just like you would on a vehicle.

Reply  •  Rated article 5  •  May 19, 2020 at 1:29 pm

• First we are not audio experts, so you may want to talk to an audio tech regarding your setup... In the end if you want to use a 12v stereo with AC power you will need a Power Supply / Converter Charger to power your equipment. Most of these can run off of a 15 amp breaker, with the exception of the 75 amp needing a 20 amp, and the 90 or 100 amp needing a 30 amp breaker. In most setups you would need a deep cycle battery meant to act as a buffer for the larger amp draws the power-supply isn't capable of outputting. Given you are no longer going to have a large amp alternator working as a power-supply you will most likely need an larger battery pack to act as a buffer. I would suggest giving our tech line a call for further information, but a lot of this may be trial an error till you come up with the right system. In the end the music being played can greatly affect your power requirements, so what works for one person may not work for another.

Reply  •  Rated article 5  •  April 28, 2020 at 8:26 am

• Love it. Gives me a better understanding when using AC appS. Inverted From DC solar system

Reply  •  Rated article 5  •  March 5, 2020 at 4:33 am

• So, if I have four 6v (200ah) batteries in series and parallel giving me a total of 400ah with a 12v inverter or if I have four 6v (200ah) batteries in series giving me a total of 200ah with a 24v inverter --- i'm not really losing any capacity (ah) because in a 24v battery bank the "appliances" would only pull half of the amps it needs, is this correct? of course both inverters a pure sine.

Reply  •  Rated article 5  •  February 19, 2020 at 6:07 am

• You are correct when it comes to the amp draw a 24v inverter will pull half the amps then a 12v inverter. You are also correct you won't see any loss if you use the same amount of batteries in your 12v setup as you would in the 24v setup. The biggest difference is when your AH remains the same... Take for instance a 12v 200 AH battery bank and a 24v 200 AH battery bank. In this case the you might think the 24v bank would last only double the time, but it actually last a little longer than double. The more amps you pull out of a battery bank the less AH capacity that battery bank is, which is why most batteries have several different AH ratings based off the Amp draw the battery is subjected to. In this case a 12v 200 AH battery pack could withstand a 10 amp draw and last only 10hrs, but the 24v 200 AH battery bank lasts 21hr 41 min. In this scenario you get an additional 1hr 41min of run time due to the less amps being drawn out of the higher voltage battery pack.

Reply  •  Rated article 5  •  March 6, 2020 at 10:31 am

• I have a small camper that I only use electricity for a few led lights and a small tv with a total load of about 75 watts at 110v I have a small 150w inverter about how long will a 100amp hour battery last before it would need to be recharged? Thanks

Reply  •  Rated article 4  •  December 7, 2019 at 4:24 pm

• Randy, even though 75 watts doesn't seem like much it can draw the battery down pretty quickly. If you inputted 110VAC at 0.68 Amps your at about 75 watts, which equates to 6.88 DC amps. You can take that figure and input it into our Calculator | Sizing a 12 Volt Battery to a Load. Ideally, you should input the hours you intend to run the inverter for, but i can tell you the 75 Watt load will drain the battery 50% in about 6.5 hrs. At that time you would need to recharge the battery to prevent excess discharge. In most situation like yours we typically see people using a much larger battery pack if they are wanting to run a TV. Obviously, this load only accounted the 75 watts, so with all of the other accessories you could easily be excessively discharging the battery each night depending on how much you are using the TV and other accessories. Most customers that intend to use an inverter and dry camp will typically start with a battery pack in the 200+ AH range.

Reply  •  Rated article 5  •  December 13, 2019 at 7:37 am

• 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  •  Rated 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  •  Rated 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  •  Rated 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  •  Rated 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  •  Rated 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  •  Rated 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  •  Rated 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  •  Rated 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  •  Rated 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  •  Rated 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  •  Rated 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  •  Rated 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  •  Rated 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  •  Rated 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  •  Rated 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  •  Rated 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  •  Rated article 4  •  February 4, 2013 at 12:04 pm

• Nice tool
Thanks

Reply  •  Rated 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  •  Rated 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