irb(main):033:0> 20.years => 20 years # ?????? irb(main):030:0> 20.years.to_i => 631152000 # number of seconds in 20 year

irb(main):033:0> 20.years => 20 years # ?????? irb(main):030:0> 20.years.to_i => 631152000 # number of seconds in 20 years irb(main):026:0> 20.years.from_now => Sun Feb 10 10:14:11 +1100 2030 # AEDT irb(main):027:0> 20.years.from_now.utc => Sat Feb 09 23:14:14 UTC 2030 # UTC/GMT Ruby Time instances have a timezone, calling Time#utc returns the instance time converted from localtime -- or whatever timezone it is -- to UTC or Greenwich Mean Time. You are correct in that it shouldn't matter which one you use in this situation though.