diff --git a/app/models/usda_food.rb b/app/models/usda_food.rb
index e9fb5db..824406e 100644
--- a/app/models/usda_food.rb
+++ b/app/models/usda_food.rb
@@ -13,4 +13,10 @@ class UsdaFood < ActiveRecord::Base
     end
   end
 
+  def density_best_guess
+    usda_food_weights.each do |w|
+
+    end
+  end
+
 end
\ No newline at end of file
diff --git a/app/models/usda_food_weight.rb b/app/models/usda_food_weight.rb
index a57bd6a..fdd05d0 100644
--- a/app/models/usda_food_weight.rb
+++ b/app/models/usda_food_weight.rb
@@ -2,4 +2,22 @@ class UsdaFoodWeight < ActiveRecord::Base
 
   belongs_to :usda_food
 
+  def calculate_density
+    return nil if gram_weight.blank? || description.blank? || amount.blank?
+
+    begin
+      value_unit = UnitConversion.parse(amount, description)
+      if value_unit.volume?
+        density_value = gram_weight.to_d / value_unit.raw_value
+        density_units = "g/#{value_unit.unit.unit}"
+        density = UnitConversion.parse(density_value, density_units)
+        return density.convert('oz/cup')
+      else
+        return nil
+      end
+    rescue UnitConversion::UnparseableUnitError
+      return nil
+    end
+  end
+
 end
\ No newline at end of file
diff --git a/lib/usda_importer.rb b/lib/usda_importer.rb
index dc274ec..7822f6c 100644
--- a/lib/usda_importer.rb
+++ b/lib/usda_importer.rb
@@ -167,11 +167,11 @@ class UsdaImporter
               file_info = FILES[name]
               obj = food
 
-              if file_info[:map_into]
-                obj = food.send(file_info[:map_into]).build
-              end
-
               rows.each do |row|
+                if file_info[:map_into]
+                  obj = food.send(file_info[:map_into]).build
+                end
+
                 file_info[:map].each do |db, col|
                   obj.send("#{db}=", row[col])
                 end
@@ -190,47 +190,6 @@ class UsdaImporter
       sorted_files.each { |k, v| `rm #{v}` }
     end
 
-    # UsdaFood.delete_all
-    #
-    # food_data_lookup = {}
-    #
-    # CSV.open(File.join(@directory, 'FOOD_DES.txt'), 'r:iso-8859-1:utf-8', csv_options(FOOD_DATA_COLUMNS)) do |csv|
-    #   csv.each do |row|
-    #     food_data_lookup[row['NDB_No']] = row.to_h
-    #   end
-    # end
-    #
-    # CSV.open(File.join(@directory, 'ABBREV.txt'), 'r:iso-8859-1:utf-8', csv_options(ABBREV_COLUMNS)) do |csv|
-    #   csv.each_slice(500) do |slice|
-    #     UsdaFood.transaction do
-    #
-    #       attributes = slice.map do |row|
-    #         attrs = Hash[ABBREV_COLUMN_MAP.map { |db, col| [db, row[col]] }]
-    #         lookup = food_data_lookup[attrs[:ndbn]]
-    #         if lookup
-    #           extra_attrs = Hash[FOOD_DATA_COLUMN_MAP.map { |db, col| [db, lookup[col]] }]
-    #           attrs.merge!(extra_attrs)
-    #         end
-    #         attrs
-    #       end
-    #
-    #       UsdaFood.create(attributes)
-    #
-    #     end
-    #   end
-    # end
-    #
-    # usda_items = Hash[UsdaFood.where(ndbn: Ingredient.select(:ndbn)).map { |uf| [uf.ndbn, uf] }]
-    #
-    # Ingredient.where('ndbn IS NOT NULL').each do |i|
-    #   item = usda_items[i.ndbn]
-    #
-    #   if item
-    #     i.set_usda_food(item)
-    #     i.save
-    #   end
-    # end
-
   end
 
   def build_enumerator(opened_files)
diff --git a/spec/factories/usda_food_weights.rb b/spec/factories/usda_food_weights.rb
new file mode 100644
index 0000000..229c420
--- /dev/null
+++ b/spec/factories/usda_food_weights.rb
@@ -0,0 +1,10 @@
+FactoryGirl.define do
+
+  factory :usda_food_weight do
+    amount 1
+    description 'cup'
+    gram_weight 350
+    usda_food
+  end
+
+end
diff --git a/spec/lib/usda_importer_spec.rb b/spec/lib/usda_importer_spec.rb
index 782b5cf..d76844f 100644
--- a/spec/lib/usda_importer_spec.rb
+++ b/spec/lib/usda_importer_spec.rb
@@ -1,5 +1,16 @@
 require 'rails_helper'
+require 'usda_importer'
 
 RSpec.describe UsdaImporter do
 
+  it 'imports' do
+    i = UsdaImporter.new(Rails.root.join('spec', 'test_data'))
+    i.import
+
+    expect(UsdaFood.count).to eq 2
+    butter = UsdaFood.where(ndbn: '01001').first
+    expect(butter).not_to be_nil
+    expect(butter.usda_food_weights.count).to eq 4
+  end
+
 end
\ No newline at end of file
diff --git a/spec/models/usda_food_weight_spec.rb b/spec/models/usda_food_weight_spec.rb
new file mode 100644
index 0000000..0b0728f
--- /dev/null
+++ b/spec/models/usda_food_weight_spec.rb
@@ -0,0 +1,21 @@
+require 'rails_helper'
+
+RSpec.describe UsdaFood do
+
+  describe '#calculate_density' do
+
+    it 'returns nil for invalid values' do
+      expect(build(:usda_food_weight, description: nil).calculate_density).to be_nil
+      expect(build(:usda_food_weight, amount: nil).calculate_density).to be_nil
+      expect(build(:usda_food_weight, gram_weight: nil).calculate_density).to be_nil
+      expect(build(:usda_food_weight, description: 'cats').calculate_density).to be_nil
+    end
+
+    it 'returns a density in oz / cup' do
+      expect(build(:usda_food_weight).calculate_density.raw_value).to be_within(0.1).of(12.3)
+      expect(build(:usda_food_weight).calculate_density.unit.to_s).to eq 'ounce/cup'
+    end
+
+  end
+
+end
\ No newline at end of file