At the very least you need to reduce that by 20%. USB batteries are about 80% efficient at most.
Okay, Iām taking crazy pills this morning, apparently. iPhoneās take about 1A to fully charge at 5V so it would actually be 10 full charges.
Well, bullshit aside, I mean. I think we can safely assume a bunch of bullshit. I donāt think Iāve ever used a battery that lasted as long as it said it would. Many donāt seem to do half.
And 10 - 20% = 8, which is what I said initially! (Not that it even is what I said initially, butā¦ uhā¦ look over there!)
10,000/1,440=6.94, not 8. Reduce 6.94 by 20% and you get 5.55 - consistent with what the #2 Amazon review by Yougotit says, that they get 5 iPhone 5 recharges from the unit, plus a little left over.
You have to read what @JeffreyM said to me and my subsequent response. My first calculation was total bullshit because you canāt just convert mAh in one battery to another when they output different voltages. In the real world, USB charging an iPhone 5 takes 2 hours and 5V and 0.5A, so it takes 1Ah at 5V which is one tenth of the battery. Initially I said it would multiply your battery life by 8, which is to say it will add 7 times the battery life to it (6.94). Hence, 10 (real number of charges) - 20% = 8 which is how I phrased my initial answer of 7.
Plus, I misread what @Shaddack said above to top things off.
Basically, you could just replace all my posts with, āWell, Iām pretty dumb, but 10,000mAh sounds like a lot!ā
(But I stand by 10Ah, what the hell is up with thousands of milli-things?)
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Thatās a lot of math. Why canāt all batteries be rated in a new unit iPc ::= iPhone charges?
Iād prefer they be rated by how long and how hot they will burn when they spontaneously combustā¦
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Why donāt you just call it a 10Ah portable USB charger?
Most electronics that are āfulfilled by Amazonā or directly sold by Amazon cannot ship to Canada from Amazon.com.
As for the item in the OPā¦ Iām always wary of mAh claims in general, but Iāve had good luck with this one, which does have free shipping to Canada but isnāt quite as cheap. 
Why donāt you call it a 50WHr portable USB charger?
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