iOS Ref

iOS version by device

iPhone

Device Released First iOS Max iOS
iPhone X 2017 11 11
iPhone 8 / 8 Plus
iPhone 7 / 7 Plus 2016 10
iPhone SE 9
iPhone 6s / 6s Plus 2015
iPhone 6 / 6 Plus 2014 8
iPhone 5s 2013 7
iPhone 5c 10
iPhone 5 2012 6
iPhone 4s 2011 5 9
iPhone 4 2010 4 7
iPhone 3GS 2009 3 6
iPhone 3G 2008 2 4
iPhone (gen 1) 2007 1 3

iPad

Device Released First iOS Max iOS
iPad Pro 12.9" (gen 2) 2017 10 11
iPad Pro 10.5"
iPad (gen 5)
iPad Pro 9.7" 2016 9
iPad Pro 12.9" (gen 1) 2015
iPad mini 4
iPad mini 3 2014 8
iPad Air 2
iPad mini 2 2013 7
iPad Air (gen 1)
iPad (gen 4) 2012 6 10
iPad mini (gen 1) 9
iPad (gen 3) 5 9
iPad 2 2011 4
iPad (gen 1) 2010 3 5

iPod touch

Device Released First iOS Max iOS
iPod touch (gen 6) 2015 8 11
iPod touch (gen 5) 2012 6 9
iPod touch (gen 4) 2010 4 6
iPod touch (gen 3) 2009 3 5
iPod touch (gen 2) 2008 2 4
iPod touch (gen 1) 2007 1 3