Watt-hours and amp-hours are both units for electric charge.
1 watt-hour is defined as 1 watt of power expended for 1 hour.
1 amp hour is defined as 1 amp of current expended for 1 hour.
How do you convert watt-hours to amp-hours?
It is possible to convert watt-hours to amp-hours using the following formula:
Watt-hours = Amp-hours * Volts
To calculate amp-hours from watt-hours, we need to rearrange this equation to:
Amp-hours = Watt-hours / Volts
For the watt-hour to amp-hour conversion, you also need voltage (V).
Here is a nifty calculator that converts watt-hours to amp-hours. Further on, you’ll also find a chart of Wh to Ah for 120V and 220V.
Wh To Ah Calculator
Watt-Hours To Amp-Hours Conversion Chart
| Watt-Hours (Wh) | Amp-Hours (at 120V): | Amp-Hours (at 220V): |
|---|---|---|
| 1 amp hour to watt hours: | 0.008 Ah | 0.005 Ah |
| 10 amp hours to watt hours: | 0.08 Ah | 0.05 Ah |
| 20 amp hours to watt hours: | 0.17 Ah | 0.09 Ah |
| 30 amp hours to watt hours: | 0.25 Ah | 0.14 Ah |
| 40 amp hours to watt hours: | 0.33 Ah | 0.18 Ah |
| 50 amp hours to watt hours: | 0.42 Ah | 0.23 Ah |
| 100 amp hours to watt hours: | 0.83 Ah | 0.45 Ah |
| 200 amp hours to watt hours: | 1.67 Ah | 0.91 Ah |
| 500 amp hours to watt hours: | 4.17 Ah | 2.27 Ah |
| 1000 amp hours to watt hours: | 8.33 Ah | 4.55 Ah |
if i have one appliance that draw 350 watts at 120 volts and i use a 100 amp hour lutetium battery will it last me 34 hour if drained 100% or am i figuring something wrong
Hello William, that appliance draws about 3 amps (350W/120V = 2.9 amps). 100 amp hours battery will supply 1 amp of electrical current for 100 hours. Or, as in your case, it will provide 3 amps for about 34 hours. That’s the basic logic. That does presume that your voltage is 120V; however, most batteries have 12V voltage. That will increase the electrical current you need to use to generate 350W by 10. That means that draw will be 30 amps; and the battery will last only 3.4 hours.
Where did you get the 10? I have 200ah lifepo4 battery and 110w consume. How long will it drain the battery?
Hello Alfred, factor 10 comes from different voltages, 120V vs 12V, the ratio is 10. 200 Ah battery has lifepo4 4 cells with about 3V voltage each, bringing the total to 12V. 110W consumption is probably on 120V; it runs on 110W/120V = 0.92 amps. You calculate 200 Ah / 0.92 A = 217 h. The 110W device should drain the battery in about 217 hours.
If I have a small solar panel capable of 30w optimally, and a portable fridge that operates at an average 0.89ah/Hr @12v that works out to 0.89×12= 10.86 w/hr, does that mean the 30w panel could operate the fridge without assistance from an external battery source, given the panel is in direct sunlight conditions for the hours needed to operate in the day time? If so, then even at half solar output (15w) it would still manage to operate the fridge? Thanks
Hello John, your calculations are on point. If your solar panel can provide 30W of power, it will run a 10.86W fridge. Even at the half output, it should be enough.
I am looking at electric bicycles. One bike I’m looking at has a 960wh battery and a 1200watt motor, and the other one has a 52v 19.2ah battery and a 1000watt motor. I can’t tell which one is better. Help!
Hello Jasmine, an interesting question. So, the key here is to calculate the battery of the second bike. You have to multiply 52V and 19.2ah and you get 998.4wh. The first bike has a more powerful motor but shorter battery life. The second bike has a less powerful motor but a better battery life. Hope this helps.
Hello, I’m looking at buying the ICECO VL60 dual Frig and Freezer that draws 45w and I have a 300w of solar panels to a 100AH Lithium Iron smart battery. The only other draw is from 3w LED lights and a 3w fan for my composting toilet. Can my system handle the ICEO? Thanks
Andy
Hello Andrew, if your solar panels continually provide 300 watts of power, you can it can easily handle 45W + 3W + 3W = 51W of power draw. Of course, the problem is that solar panels don’t continually provide 300W.
Let’s say that power flow drops to 0W during the night. For how long can the 100 Ah battery provide power to appliances with the combined wattage of 51W? Well, 100 Ah battery probably has 12V voltage; that means that at full capacity, the battery stores 1,200 Wh. 1,200 Wh / 51W = 23,5 hours. That 100 Ah battery can provide power to the whole system (freezer + LED lights + fan) for about 24h.
All in all, the system can handle the new freezer. Hope this helps.
Hello,
Could I ask a question please? I have two leisure batteries that each have 95amp/h or 1140 watt hours.
I have a cool box, in the information leaflet it details the consumption as 55w on 12v. Does that mean 55w per hour? I can’t find anything to indicate an hourly rate.
If so then does that mean that I could run that cool box for just over 41 hours?
Thank you.
Trish
Hello Trish, two batteries combined have a capacity of 2280 Wh (at 12V). The cool box runs on 55 Watts; it will drain 55 Wh (every hour). That means that the cool box will run for 2280 Wh / 55 W = 41.5 hours; as you have correctly calculated, well done!
Convert 338 w to Ah
Hello Bassey, for every conversion, you also need voltage. Let’s say you have a standard 12V battery that produces 338W output. That means the battery generates 338W / 12V = 28.2 amps. That would mean that 338 Wh is equal to 28.2 Ah. Hope this helps.
How many batterys do I need to run 1000w for 5 hours
What size battery
How many amp
And for 3000w
Hello Bailey, 1000W for 5 hours is equal to 5 kWh. Batteries have 12V voltage; in this case, you would need a 416.67 Ah battery. Such a battery has an 83.3 amp output. For 3000W, you just multiply these numbers by 3 and you get the numbers.
Hi, I would like to ask the following
I’m looking to buy a power station for emergency power outage in the winter.
Specifically, I’m planning to use a 1500W room heater for 8hr in such setting, which I haven’t found one yet, but I did find a power station stating 1260Wh with some 120V 15amp outlets. I’m confused as it also said “AC inverter output: 1800W continuous.”
So would this power station good enough or I may need a bigger capacity one.
Hello Brooks, first you need to check if the output wattage is sufficient (at least 1,500W). The 120V 15amp output generates 120V*15A = 1,800W. This checks out, great. Now, 1,260 Wh means that such a power station can provide 1,260W wattage for 1 hour. You can power a 1,500W for about 50 minutes. So, not 8 hours. This is a very small power station; you would need a bigger one.
So interesting
Am very grateful for your explanation