Shopping Cart Total Calculator
How it works
Each row's price times its quantity is added up into a subtotal. The discount percentage is taken off that subtotal first, and only then is the tax rate applied — to what is left after the discount, not to the original subtotal — matching how a real checkout charges tax on the price actually being paid.
Frequently asked questions
Which comes first, the discount or the tax?
The discount, then tax on what's left. A coupon takes a percentage off the goods themselves, and sales tax is then charged on the amount actually being paid — not on the pre-discount price. Taxing the full price first and discounting afterwards would charge tax on money the customer never pays, giving a higher, incorrect total whenever a discount applies.
Why can quantity not be zero?
A line item with zero quantity is not really in the cart — it contributes nothing to the subtotal either way, so remove the row instead of setting its quantity to 0.
How is this different from the Unit Price Calculator?
The Unit Price Calculator compares the price per unit of two separate pack sizes to find which is the better deal. This tool does not compare anything — it totals an entire cart of named items, each with its own price and quantity, and applies one discount and one tax rate across the whole thing.