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Sometimes you know the final, tax-inclusive price (like a total from a receipt) and need to work backward to find the original pre-tax price — the opposite direction from the standard Sales Tax Calculator, which starts from a pre-tax price.
This calculator takes a tax-inclusive total and the tax rate, and backs out the original pre-tax price and the tax amount.
How it works
Enter the total price (with tax already included) and the tax rate. The tool divides the total by (1 + tax rate) to find the pre-tax price, then subtracts to find the tax amount.
- Enter total price (tax included, $).
- Enter tax rate (%).
- Click Calculate to see your results.
Examples
A $108.50 receipt total
A $108.50 total with an 8.5% tax rate backs out to a $100 pre-tax price and $8.50 in tax.
Who should use it
- Finding the pre-tax price of a purchase from a receipt or invoice total.
- Reconciling bookkeeping records that only recorded tax-inclusive totals.
Industry applications
- Personal and small business bookkeeping
- Retail and accounting
Advantages
- Correctly reverses the sales tax formula rather than approximating it.
- Useful for reconciling receipts or accounting records with only a tax-inclusive total.
Limitations
- Requires knowing the exact tax rate that was applied — an incorrect rate will give an incorrect pre-tax price.
Common mistakes to avoid
- Simply subtracting the tax rate percentage from the total price, which gives an incorrect result — tax is calculated on the pre-tax price, not the total.
- Using the wrong tax rate (e.g., a state rate without including local/city tax that was actually applied).
Best practices
- Use the exact combined tax rate that was actually applied (state plus any local tax) for an accurate reverse calculation.
Tips
- If you're not sure of the exact tax rate applied, check a recent receipt from the same location — the rate is usually printed at the bottom.