With this ruby script, you will be able to calculate how many minutes left to complete 1 more hour of utilization.

calc_ec2_time_left.rb

#!/usr/bin/ruby
# ##########################################################
# Encoding: UTF-8
# calc_ec2_time_left.rb
# With this ruby script, you will be able to calculate
# how many minutes left to complete 1 more hour of 
# utilization.
# Wesley Rodrigues da Silva <wesley.it at gmail.com>
# LICENCE CREATIVE COMMONS BY - 2014
# http://creativecommons.org/licenses/by/2.0/legalcode
# ########################################################
 
require 'date'
require 'json' 
require 'open-uri' 
 
@json = JSON.parse(open('http://169.254.169.254/latest/dynamic/instance-identity/document').read)
@started = @json['pendingTime'].split('T')[1].split(':')[1].to_i
@now = Time.now.strftime("%M").to_i
@time_left = ( 60 - @started + @now ) % 60