Sales Tax Calculator

Adding tax is a multiplication; removing it is a division. The asymmetry catches people out, because taking the tax percentage off a tax-inclusive total leaves you short.

• Subtotal = amount × number of items
• Adding tax: tax = subtotal × rate ÷ 100, total = subtotal + tax
• Removing tax: subtotal = total ÷ (1 + rate ÷ 100), tax = total − subtotal

Adding tax multiplies the subtotal by the rate; removing it divides a tax-inclusive total by one plus the rate. The pre-tax subtotal is the figure bookkeeping needs.

Common mistakes and assumptions

• Subtracting the tax percentage from a tax-inclusive total, which always leaves you short.
• Using a state rate when a county or city rate also applies — enter your combined rate.
• Assuming everything is taxable; exemptions vary and are not applied here.

A $63.60 receipt total in an 8.25% tax area, and you need the pre-tax figure.

1. 1Divide by 1 + the rate: $63.60 ÷ 1.0825 = $58.75.
2. 2Tax included = $63.60 − $58.75 = $4.85.
3. 3Check forward: $58.75 × 0.0825 = $4.85, and $58.75 + $4.85 = $63.60.
4. 4Subtracting 8.25% from $63.60 instead would give $58.35 — wrong by $0.40.
5. 5The tax is 7.62% of the total even though the rate is 8.25% of the subtotal.

Why can't I just subtract the tax rate from the total?

Because the rate applies to the subtotal, not the total. The correct reverse operation is dividing by 1 plus the rate.

What rate should I use?

Your combined rate: state plus county plus city plus any special district. A receipt is the most reliable source for your exact local figure.

Are all purchases taxed the same?

No. Many states exempt groceries and prescriptions or tax them at a lower rate, and rules for services differ widely. This calculator applies one rate to whatever you enter.

Is this the same as VAT or GST?

The arithmetic is identical, so you can use it for any single-rate consumption tax. VAT prices are usually shown tax-inclusive, so the remove mode is the one you want.