How much data is used during factory reset recovery mode for the Mac OS? I boot my Mac air into recovery mode over internet command+option+R (recovery drive has been deleted/overwritten).

I am using mobile tethering to recover this device, just enquiring as to how much data will be used during this process if anyone can advise? I am unsure of the size of the recovery image it wants to download.

p.s this is my only available recovery method, there are no ethernet ports on the laptop and it will not pick up our business Wi-Fi (we use WPA2-Enterprise which is supported but on a Cisco Meraki account basis, so it's not a case of SSID / Pass).
Each size (Internet Recovery Mode and OS X reinstall) is comparable to the sizes of the respective dmg files containing the Base OS X/full OS X install.

So booting once to Internet Recovery Mode requires the download of about 650 MB and restoring your original operating system – which depends on your MacBook Air model – requires an additional download of about ~4.7 GB (Lion) to ~5.7 GB (Yosemite).

You can't download and install El Capitan directly because the original system of the newest MacBook Air was 10.10.2.