Basically, the amount of capacity (mAh) you need to charge a phone depends on the capacity (mAh) of the phone’s battery. Some phone models need more mAh to get charged while others require less.
If you ask any person who is looking to purchase a power bank, the first feature that they’ll mention is the capacity thanks to the common belief that the more the mAh, the bigger the charging capacity of the device. While this is true, when buying a power bank most buyers ignore that their advertised capacity is misleading, so they usually get tricked and end up with a power bank that is short of their expectations.
To prevent this from happening to you, we have designed an easy guide so that you can better choose a power bank based on the actual capacity of your smartphone.
Real vs advertised capacity
From a technical point of view, the main reason behind this disparity is represented by power losses; however, we cannot overlook the business-savvy nature of manufacturers, who disguise the real capacity to boost their sales.
To learn in detail about this difference in real and advertised capacity, check our article “Why is there a difference between rated and real battery capacity?”
How to calculate the actual capacity before buying a power bank?
As we’ve learned this mismatch of power between smartphones and power banks leads to confusion, which is why it’s not so uncommon to see many users buying power banks that can’t even supply a full charge to their devices.
To avoid this, we’ve stuck to the general rule of thumb of 2/3* of the power bank’s advertised capacity. This time, using the following way:
minimum capacity required for 1 charge = smartphone capacity * 1/(2/3)
minimum capacity required for 1 charge = smartphone capacity * 1.5
The explanation behind this equation is simple. As we know, the actual capacity of a power bank is close to 2/3, which is the result of the energy lost in the voltage conversion and transfer. Although the advertised capacity of the power bank is unknown to us, we do know the battery size of our smartphone.
In this sense, we need to look for a power bank that outputs this value, so this number should make up for the 1/3 loss in the transfer and voltage conversion. For this reason, we use the multiplicative inverse of 2/3 or 0.666, which in this case is 1.5.
This indicates that the power bank needs to be 1.5 bigger in capacity than one of our smartphones.
Should you want to calculate how many mAh the power bank needs to have to supply more than 1 charge, let’s say 2 or 3, simply multiply the result of the first equation by the number of times, as this next equation shows:
minimum capacity required for X charges = smartphone capacity * 1.5 * X
*Please note that 2/3 is a gross estimation. This will largely depend on the power bank quality. Some high-quality power banks can achieve higher efficiency rates, potentially as high as 80-90%. Not all power banks are made equal, and a power bank’s quality can significantly affect its performance. Even two power banks with the same capacity might not deliver the same number of charges due to differences in efficiency and construction quality.
Another important thing to know is that, as batteries age, their efficiency declines and they might require more energy to reach a full charge. The actual number of full charges a power bank can deliver might be fewer than calculated if the phone’s battery health has deteriorated.
Phone usage during the charging process
Using your phone while it is charging from the power bank will consume power, potentially reducing the number of full charges the power bank can deliver. So when taking into account the estimated calculations above, please note that they refer to the process of charging a phone while it’s not being actively used.
Obviously, the more energy the phone consumes, the more mAh will be needed to replenish its battery. Different phone usage behaviors will have different battery consumption rates. For example, playing games on the phone is one of the fastest ways to deplete its battery, more so if there are any other apps running in the background simultaneously.
How many mAh to charge iPhone smartphones?
The following table contains all the iPhone models released in 2017.
| Smartphone Model | Pone battery capacity | Power bank capacity for 1 charge | Power bank capacity for 2 charges |
|---|---|---|---|
| iPhone 11 Pro Max | 3969 mAh | 5953.5 mAh | 11907 mAh |
| iPhone 11 Pro | 3046 mAh | 4569 mAh | 9138 mAh |
| iPhone 11 | 3110 mAh | 4665 mAh | 9330 mAh |
| iPhone XS Max | 3174 mAh | 4761 mAh | 9522 mAh |
| iPhone XS | 2658 mAh | 3987mAh | 7974 mAh |
| iPhone XR | 2942 mAh | 4413 mAh | 8826 mAh |
| iPhone X | 2716 mAh | 4074 mAh | 8148 mAh |
| iPhone 8 Plus | 2691 mAh | 4036.5 mAh | 8073 mAh |
| iPhone 8 | 1821 mAh | 2731.5 mAh | 5463 mAh |
| iPhone 7 Plus | 2900 mAh | 4350 mAh | 8700 mAh |
| iPhone 7 | 1960 mAh | 2940 mAh | 5880 mAh |
In case you still own an iPhone 6, just make sure to find the battery capacity and use our formula to do the corresponding calculation.
How many mAh to charge Samsung phones?
Likewise, the following is a table with the most popular and latest Samsung models.
| Smartphone Model | Pone battery capacity | Power bank capacity for 1 charge | Power bank capacity for 2 charges |
|---|---|---|---|
| Samsung Galaxy Note 10+/Note 10+ 5G | 4300 mAh | 6450 mAh | 12900 mAh |
| Samsung Galaxy Note 10 | 3500 mAh | 5250 mAh | 10500 mAh |
| Samsung Galaxy Note 9 | 4000 mAh | 6000 mAh | 12000 mAh |
| Samsung Galaxy Note 8 | 3300 mAh | 4950 mAh | 10500 mAh |
| Samsung Galaxy Note 7 | 3500 mAh | 5250 mAh | 10500 mAh |
| Samsung Galaxy S20 Ultra | 5000 mAh | 7500 mAh | 15000 mAh |
| Samsung Galaxy S20+ | 4500 mAh | 6750 mAh | 13500 mAh |
| Samsung Galaxy S20 | 4000 mAh | 6000 mAh | 12000 mAh |
| Samsung Galaxy S10 5G | 4500 mAh | 6750 mAh | 13500 mAh |
| Samsung Galaxy S10+ | 4100 mAh | 6050 mAh | 12300mAh |
| Samsung Galaxy S10e | 3100 mAh | 4650 mAh | 9300 mAh |
| Samsung Galaxy S10 | 3400 mAh | 5100 mAh | 10200 mAh |
| Samsung Galaxy S9+ | 3500 mAh | 5250 mAh | 10500 mAh |
| Samsung Galaxy S9 | 3000 mAh | 4500 mAh | 9000 mAh |
| Samsung Galaxy S8 Active | 4000 mAh | 6000 mAh | 12000 mAh |
| Samsung Galaxy S8+ | 3500 mAh | 5250 mAh | 10500 mAh |
| Samsung Galaxy S8 | 3000 mAh | 4500 mAh | 9000 mAh |
| Samsung Galaxy A50/A30/A20 | 4000 mAh | 6000 mAh | 12000 mAh |
| Samsung Galaxy A70/ A90 5G | 4500 mAh | 6750 mAh | 13500 mAh |
| Samsung Galaxy A10 | 3400 mAh | 5100 mAh | 10200 mAh |
As seen, just like the iPhone list, this one contains only models from 2017 onwards and leaves out many other models, including the J and M series. On top of that, as dynamic as Samsung is, we can only expect more new releases in the upcoming months. So, if your model is new or has not been listed, check its battery size and then do the math using the formula previously explained.
How many mAh to charge Google Pixel phones?
Lastly, here’s the table with all the Google Pixel smartphone models so far on the market.
| Smartphone Model | Pone battery capacity | Power bank capacity for 1 charge | Power bank capacity for 2 charges |
|---|---|---|---|
| Google Pixel 4 XL | 3700 mAh | 5550 mAh | 11100 mAh |
| Google Pixel 4 | 2800 mAh | 4200 mAh | 8400 mAh |
| Google Pixel 3a XL | 3700 mAh | 5550 mAh | 11100 mAh |
| Google Pixel 3a | 3000 mAh | 4500 mAh | 9000 mAh |
| Google Pixel 3 XL | 3430 mAh | 5145 mAh | 10290 mAh |
| Google Pixel 3 | 2915 mAh | 4372.5 mAh | 8745 mAh |
| Google Pixel 2 XL | 3520 mAh | 5280 mAh | 10560 mAh |
| Google Pixel 2 | 2700 mAh | 4050 mAh | 8100 mAh |
| Google Pixel XL | 3450 mAh | 5175 mAh | 10350 mAh |
| Google Pixel | 2770 mAh | 4155 mAh | 8310 mAh |
Finding the right power bank for your cellphone
As seen in the tables, the values are estimations, so it’s highly unlikely to find a power bank that matches that exact number. Therefore, what we advise is to choose a power bank with a capacity that is slightly bigger than the one the table indicates. This way, you can ensure you’ll have a power bank capable of recharging your smartphone a certain number of times.
For example, if you’re looking for a power bank with enough power to charge your phone at least two times, you should then pick one with a capacity of over 12000 mAh. Thus, we found that the INIU BI-B5, for example, is able to do so satisfactorily.
So, you must be asking how we found the right charger. Well, with the help of our Power Bank Review Finder, a simple but useful tool in which you can specify the capacity, as other as other important features such as the number of ports and charging technology.
Final Thoughts
Despite false claims by manufacturers, choosing a suitable power bank for your smartphone has never been this easy, as it is with this helpful guide.
However, focusing exclusively on capacity is not ideal, as you can end up choosing a power bank that does not work at all with your phone or that charges it slowly. Thus, pay close attention to other important elements when picking the most suitable power bank, such as the charging technology and compatible ports.
