The Price Comparison Calculator compares the prices of items with variable weights and volumes in different units (e.g. pounds, kilograms, gallons and liters) and with different currencies (e.g. Euros, Yuan).  The calculator performs all of the math associated with the unit conversions and provides a simple answer informing the user which product is the least expensive and by how what percentage.  Note: currency exchange rates fluctuate and are updated every two minutes.  See INSTRUCTION VIDEO HERE.

This set of equations can help you save money by comparing the prices and amounts of items,.  The equations are sorted by the kind of "amount"- mass, volume, or both.  The markups for these equations defaults to American Dollars, but they can be changed to a wide range of currencies.  You can even mix and match currencies (i.e. you could compare an item in USD to an item in Euros).

Price/Mass:

   If you're looking at two items, each with different prices and masses (such as 2 pounds of beef for $15.50 and 3 pounds of beef for $21.34), then all that's standing in the way of you finding the best buy is a bit of math.  The red buttons are here to do that math for you- just click the button for the right amount of items (2, 3, or 4) and follow the instructions.

Price/Volume:

  Comparing by mass is well and good, but not every item is sold by the pound.  For items that are described with price and volume (gallon, liter, fluid ounces, etc.), you can use the blue buttons- just click the button for the right amount of items (2, 3, or 4) and follow the instructions.

Price/Mass vs Price/Volume:

  What if, for whatever reason, you're trying to find the cheaper of two items, but one is described with units of mass (pound, kilograms, etc.) and the other is described with units of volume (gallon, liters, etc.).  First you should decide whether you going to compare the items by mass or by volume.  Next choose from the following options:

• Select the density from a list (Green Buttons):

  This calculator was originally intended to help with price comparisons in a grocery store, so a shortened list of items you might find in a foodmarket is provided so you don't have to sort through 100+ entries.

• Look up and enter the density (Purple Buttons):

  The limited list used by the green buttons might not have exactly what you're looking for, so you can instead:

1. Use the "Look Up Approximate Density" button, which provides a much more comprehensive list of everything from woods to metals to chemicals.   
2. Select the item you're look for.
3. Highlight and copy, memorize, or otherwise store the average density.
4. Use one of the two other purple buttons for a comparison and insert the density where instructed.