How much will this charge my iPhone 5?

I want to buy this charger:

http://www.amazon.co.uk/...0067UPRQ4/

(The 8400mAh version)

I've looked at the review however they're not that helpful as they are for a combination of the different powers of the charger.

I have an iPhone 5, and was wondering how many times this should charge my phone from flat? I think somewhere it says that not all the power goes to the iphone, some is used to power the device.

That's the same one i got Anker. Well when I got it new i was able to charge it from flat like dead to full and it lost a bar. Then i tried it again but I didn't let my phone die, I started to charge it at 6% and it lost another bar. Then I did it again at around the same percent. Then again cause I never charged the external battery. But the last charge didn't go fully. It stopped at around 80% so I would say about 4 charges. But if the phone were dead all those times then maybe just 3 to 3 and a half. Then iphone 5 was generally designed to use up less battery power than the iphone 4s and previous series so it will use the Anker to its full extend.

Are you getting that because you are out camping somewhere and need to charge? You may want to look into those little fold out solar chargers, from what I read it takes a long time to charge but would probably work good if out in a remote area and you could leave it charge for hours.