
Apologies in advance. I know you probably came here looking for a quick answer, but alas, I cannot provide it.
Unfortunately, there is no one-size-fits-all answer to how many mAh you’d need to charge a phone, as every phone is different. It’s kind of like asking how long a piece of string is, not that it’s a bad question by any stretch.
Some phones are simply more power-hungry than others, and thus, require a larger amount of mAh to refuel — makes sense, right?
But this uncertainty can be a real pain when we’re shopping around for a power bank. How are we supposed to know which battery will be sufficient?
Well, generally speaking, the battery capacity of most smartphones falls beneath the 4000 mAh mark, so as long as a power bank far exceeds that figure, you should be good to go.
I say “far exceeds” because a lot of the time, the advertised capacity of a power bank falls well shy of its real-life potential, which has tricked many a consumer into purchasing the wrong device.
Not to worry, though, friend — I’m not going to let that happen to you!
This guide will steer you directly to the type of power bank you need to fully recharge your phone.
Why Is There A Difference Between Real And Advertised Capacity?
The thing about advertised capacities is that they’re completely theoretical, calculated using math rather than field-testing. They’re an approximation of potential capacity in ideal circumstances.
What manufacturers (conveniently) fail to take into account are power losses.
Every energy source suffers from power loss, whether it’s a solar panel, a gas generator, or, of course, a battery. It’s just a natural occurrence for some power to get lost on the way from the source to a destination.
For portable batteries, most of this loss occurs as the current passes through a voltage converter, which is required to modify its native 3.7V into the minimum USB standard of 5V.
It sounds confusing, but really, all you need to know is that the more hoops the current has to leap through to reach its destination, the weaker it becomes, and the voltage converter is one heck of a hoop.
Can You Figure Out Actual Capacity Before Buying A Power Bank?
The only way to make sure that you don’t get duped by a deceptive power bank capacity is learning how to figure out the actual capacity yourself, and I’m going to show you how, right here, right now!
If you’re looking for an easy way to navigate this tricky consumer conundrum, my advice is just to assume that the actual capacity of a power bank is roughly ⅔ of the advertised capacity.
So, let’s say we have a power bank rated at 10,000 mAh. We’d whip out our trusty phone calculator and tap in 10,000 ÷ 3 = 3333.
Then, all we have to do is times our answer by 2, giving us 6666, and that’s your approximate real-life capacity.
By doing the following sum, we can figure out how much larger the advertised capacity of a power pack would need to be to fully charge our phone once.
1 ÷ ⅔ = 1.5
That means for one full charge, our power pack would need to have an advertised capacity at least 1 ½ times larger than our phone’s capacity, but what about multiple charges?
To glean the advertised capacity you’d need to charge your phone a number of times, simply multiply 1.5 with however many charges you want.
For example, 2 full charges would require a power pack with an advertised capacity at least 3 times the capacity of your phone.
If you want to figure out a more exact number, you’ll have to go deeper with the math. The formula goes a little something like this…
Voltage (usually 3.7V) ✕ Advertised Capacity ✕ Efficiency (in decimals) ÷ 5V = Actual Capacity
To illustrate how this works, let’s feed our earlier 10,000 mAh example through this formula, but first, we have to attribute our hypothetical power bank an efficiency rating. So, for the sake of this exercise, let’s say it is 93% efficient. This is how the equation would go…
3.7 ✕ 10,000 ✕ 0.93 ÷ 5 = 6882
And there you have it — the actual capacity of our imaginary power supply is 6882mAh, or, in other words, the charger is capable of delivering 68.82% of the advertised rating to your phone.
What mAh Would I Need To Charge An iPhone?
Each model of iPhone has a slightly different capacity, so, again, there is no singular answer to how many mAh you’d need to charge one.
That’s why I’ve created the following table of all the recent iPhone releases and their individual mAh requirements — gosh, I’m good to you!
Model | Battery Capacity | Power Pack Capacity for 1 Charge | Power Pack Capacity for 2 Charges |
iPhone 13 Pro Max | 4352 mAh | 6528 mAh | 13,056mAh |
iPhone 13 Pro | 3100 mAh | 4650 mAh | 9300 mAh |
iPhone 13 Mini | 2438 mAh | 3657 mAh | 7314 mAh |
iPhone 13 | 3227 mAh | 4840.5 mAh | 9681 mAh |
iPhone 12 Mini | 2227 mAh | 3340.5 mAh | 6681 mAh |
iPhone 12 | 2815 mAh | 4222.5 mAh | 8445 mAh |
iPhone SE | 1821 mAh | 2731.5 mAh | 5436 mAh |
iPhone 11 Pro Max | 3969 mAh | 5953.5 mAh | 11,907 mAh |
iPhone 11 Pro | 3046 mAh | 4569 mAh | 9138 mAh |
iPhone 11 | 3110 mAh | 4665 mAh | 9330 mAh |
Nice! What About Samsung Smartphones?
Here’s a table showing all the details of the latest Samsung smartphones and their required mAh rating.
Model | Battery Capacity | Power Pack Capacity for 1 Charge | Power Pack Capacity for 2 Charges |
Galaxy S21 Ultra | 5000 mAh | 7500 mAh | 15,000 mAh |
Galaxy S21 | 4000 mAh | 6000 mAh | 12,000 mAh |
Galaxy S20 FE (5G) | 4500 mAh | 6750 mAh | 13,500 mAh |
Galaxy A52 (5G) | 4500 mAh | 6750 mAh | 13,500 mAh |
Galaxy Note 20 Ultra (5G) | 4500 mAh | 6750 mAh | 13,500 mAh |
Galaxy S21 Plus | 4800 mAh | 7200 mAh | 14,400 mAh |
Galaxy S20 Plus | 4500 mAh | 6750 mAh | 13,500 mAh |
Galaxy Z Fold 3 | 4400 mAh | 6600 mAh | 13,200 mAh |
Okay, But How About Google Pixel Capacities?
Let’s bring these comparison tables to an end with one final insight, this time into Google’s proprietary Pixel smartphones.
Model | Battery Capacity | Power Pack Capacity for 1 Charge | Power Pack Capacity for 2 Charges |
Pixel 6 Pro | 5003 mAh | 7504.5 mAh | 15,009 mAh |
Pixel 6 | 4614 mAh | 6921 mAh | 13,842 mAh |
Pixel 5 | 4080 mAh | 6120 mAh | 12,240 mAh |
Pixel 4a | 3140 mAh | 4710 mAh | 9420 mAh |
Pixel 4 XL | 3700 mAh | 5550 mAh | 11,100 mAh |
Pixel 4 | 2800 mAh | 4200 mAh | 8400 mAh |
Pixel 3a | 3000 mAh | 4500 mAh | 9000 mAh |
Pixel 3 | 2915 mAh | 4372.5 mAh | 8745 mAh |
Which Is the Right Power Pack For Me And My Phone?

The right power pack for you and your phone should have an advertised capacity of at least 1.5 times the size of your battery capacity, but remember, the figures in the tables above are only loose estimates.
I’d recommend investing in a power pack with a significant amount of extra headroom, just to be sure it’s got the goods to supercharge your smartphone.
As important as charger capacity is, I’d also advise not to get too wrapped up in this single aspect of power pack design.
There are plenty of other things to consider, too, such as footprint and portability, durability, USB ports, charging technology, and brand reputability.
If I had to go out and buy just one power pack today, I’d choose the Anker PowerCore 26800. For a tiny, super-sleek power bank, it packs one hell of a punch — we’re talking a 26,800mAh punch!
That’s enough to charge even the most power-hungry phones on my comparison tables more than twice.
Summing Up
There you have it, folks — pretty much all you will ever need to know about mAh, your phone capacity, and power pack capacities is in this article, so now you can buy a portable power pack with confidence — hooray!
As long as you remember the formulas we discussed earlier, you’re guaranteed to choose one that’s suitable for your phone, and if you don’t have the formula handy when shopping, just remember that the actual capacity of a charger will be roughly ⅔ of the advertised capacity.
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