Split-Cost Coefficient Calculator (SC3)

Ever split the bill with your friends and they only pay for their subtotal, leaving you with tax, tip, etc.?

This app helps you figure out the multiplier. Here's how it works:

You have a subtotal, which is the collective cost of all the items excluding tax and tip.

Then you have a grand total, which is the collective cost of all the items including tax and tip.

If you follow this formula: subtotal / grand total, you should get the coefficient.

You can give this coefficient to your friends so they can multiply their personal subtotal with that number, and that's the money they owe you.

Example

Imagine the following receipt:

      Coffee x2 = $4
      Pancakes w/ side = $14
      Pasta = $9
      Omelette = $16

      Subtotal: $43
      Random tax (3%): $1.29
      Some other tax (4%): $1.72
      Tip (20%): $8.60

      Grand Total: $54.61
      

If you calculate for the coefficient, it will turn out to be 1.27. This is your multiplier.

Proof: If you multiply your subtotal with the coefficient, it should amount to the grand total.

      1.27 * $43 = $54.61