diff --git a/config/initializers/date_ext.rb b/config/initializers/date_ext.rb
new file mode 100644
index 000000000..15055c3cb
--- /dev/null
+++ b/config/initializers/date_ext.rb
@@ -0,0 +1 @@
+require 'date_ext'
diff --git a/lib/date_ext.rb b/lib/date_ext.rb
new file mode 100644
index 000000000..beae11125
--- /dev/null
+++ b/lib/date_ext.rb
@@ -0,0 +1,8 @@
+module AgeInYears
+  def age_in_years(now = Time.now.utc.to_date)
+    # reference: http://stackoverflow.com/questions/819263/get-persons-age-in-ruby#comment21200772_819263
+    now.year - year - ((now.month > month || (now.month == month && now.day >= day)) ? 0 : 1)
+  end
+end
+
+Date.include(AgeInYears)
diff --git a/spec/lib/date_spec.rb b/spec/lib/date_spec.rb
new file mode 100644
index 000000000..0963306e3
--- /dev/null
+++ b/spec/lib/date_spec.rb
@@ -0,0 +1,55 @@
+require 'rails_helper'
+
+describe Date do
+  describe '#age_in_years' do
+    it "calculates age correctly for common dates" do
+      d = Date.new(1980, 3, 13)
+      expect(d.age_in_years(Date.new(2000, 3, 12))).to eq(19)
+      expect(d.age_in_years(Date.new(2000, 3, 13))).to eq(20)
+      expect(d.age_in_years(Date.new(2000, 3, 14))).to eq(20)
+    end
+
+    it "calculates age correctly for people born near a year's limit" do
+      d = Date.new(1980, 12, 31)
+      expect(d.age_in_years(Date.new(2000, 12, 30))).to eq(19)
+      expect(d.age_in_years(Date.new(2000, 12, 31))).to eq(20)
+      expect(d.age_in_years(Date.new(2001,  1,  1))).to eq(20)
+
+      d = Date.new(1980, 1, 1)
+      expect(d.age_in_years(Date.new(2000, 12, 31))).to eq(20)
+      expect(d.age_in_years(Date.new(2001,  1,  1))).to eq(21)
+      expect(d.age_in_years(Date.new(2001,  1,  2))).to eq(21)
+    end
+
+    it "calculates age correctly for people born around February the 29th" do
+      # 1980 and 2000 are leap years. 2001 is a regular year
+      d = Date.new(1980, 2, 29)
+      expect(d.age_in_years(Date.new(2000,  2, 27))).to eq(19)
+      expect(d.age_in_years(Date.new(2000,  2, 28))).to eq(19)
+      expect(d.age_in_years(Date.new(2000,  2, 29))).to eq(20)
+      expect(d.age_in_years(Date.new(2000,  3,  1))).to eq(20)
+      expect(d.age_in_years(Date.new(2001,  2, 27))).to eq(20)
+      expect(d.age_in_years(Date.new(2001,  2, 28))).to eq(20)
+      expect(d.age_in_years(Date.new(2001,  3,  1))).to eq(21)
+
+      d = Date.new(1980, 2, 28)
+      expect(d.age_in_years(Date.new(2000,  2, 27))).to eq(19)
+      expect(d.age_in_years(Date.new(2000,  2, 28))).to eq(20)
+      expect(d.age_in_years(Date.new(2000,  2, 29))).to eq(20)
+      expect(d.age_in_years(Date.new(2000,  3,  1))).to eq(20)
+      expect(d.age_in_years(Date.new(2001,  2, 27))).to eq(20)
+      expect(d.age_in_years(Date.new(2001,  2, 28))).to eq(21)
+      expect(d.age_in_years(Date.new(2001,  3,  1))).to eq(21)
+
+      d = Date.new(1980, 3, 1)
+      expect(d.age_in_years(Date.new(2000,  2, 27))).to eq(19)
+      expect(d.age_in_years(Date.new(2000,  2, 28))).to eq(19)
+      expect(d.age_in_years(Date.new(2000,  2, 29))).to eq(19)
+      expect(d.age_in_years(Date.new(2000,  3,  1))).to eq(20)
+      expect(d.age_in_years(Date.new(2001,  2, 27))).to eq(20)
+      expect(d.age_in_years(Date.new(2001,  2, 28))).to eq(20)
+      expect(d.age_in_years(Date.new(2001,  3,  1))).to eq(21)
+    end
+
+  end
+end