DwMoney is a flexible solution for conversion and arithmetics with different currencies.

Add this line to your application's Gemfile:

gem 'dw_money'

And then execute:

$ bundle

Or install it yourself as:

$ gem install dw_money

Configuring the currency rates with respect to a base currency (here EUR):

DwMoney::Money.conversion_rates('EUR', {
  'USD'     => 1.11,
  'Bitcoin' => 0.0047
})

fifty_eur = DwMoney::Money.new(50, 'EUR')
fifty_eur.amount   # => 50
fifty_eur.currency # => "EUR"
fifty_eur.inspect  # => "50.00 EUR"

fifty_eur.convert_to('USD') # => 55.50 USD

twenty_dollars = DwMoney::Money.new(20, 'USD')

fifty_eur + twenty_dollars # => 68.02 EUR
fifty_eur - twenty_dollars # => 31.98 EUR
fifty_eur / 2              # => 25 EUR
twenty_dollars * 3         # => 60 USD

twenty_dollars == DwMoney::Money.new(20, 'USD') # => true
twenty_dollars == DwMoney::Money.new(30, 'USD') # => false

fifty_eur_in_usd = fifty_eur.convert_to('USD')
fifty_eur_in_usd == fifty_eur                   # => true

twenty_dollars > DwMoney::Money.new(5, 'USD')   # => true
twenty_dollars < fifty_eur                      # => true

After checking out the repo, run bin/setup to install dependencies. Then, run rake spec to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.

Bug reports and pull requests are welcome on GitHub at https://github.com/pedrovitti/dw_money.

The gem is available as open source under the terms of the MIT License.