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Reverse Tax Calculator — Find Pre-Tax Price from Total

Work backwards from total price to find pre-tax amount and tax paid. US state rates, VAT, GST, HST presets included. Supports multiple items.

Updated

Formula: Pre-tax = Total ÷ (1 + rate). Tax = Total − Pre-tax.
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How to Use This Calculator

  1. 1

    Enter the total price you paid

    Enter the final amount shown on your receipt or invoice — the amount that includes tax. This is the number after tax has been added.

  2. 2

    Enter the tax rate

    Type the tax rate as a percentage, or use the preset dropdown to select a US state combined rate, UK VAT, Canadian GST/HST, Australian GST, or other international rate. The rate is applied to all items unless changed per item.

  3. 3

    Add multiple items if needed

    Click 'Add another item' to reverse-calculate multiple purchases at once. Each item can have a different rate. The summary section shows combined totals across all items.

What Each Value Means

Pre-Tax Price ($)
The original price of the item before tax was added. Calculated as: total ÷ (1 + tax rate). This is the taxable amount — what the seller charges before the government's share is added.
Tax Paid ($)
The portion of your total payment that went to tax. Calculated as: total − pre-tax. Equivalent to: total × (rate / (1 + rate)). This is not the same as total × rate — that formula overstates the tax by applying the rate to the final price rather than the original price.

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Frequently Asked Questions

How do you calculate pre-tax price from a total that includes tax?
Pre-tax price = Total price ÷ (1 + tax rate). For example, $108 total with 8% tax: $108 ÷ 1.08 = $100.00 pre-tax. The tax amount is $108 − $100 = $8.00. This formula works for US sales tax, VAT, GST, and HST — any flat-rate tax added to a price. Do NOT divide by the tax rate alone (that gives the wrong answer).
Why can't I just multiply the total by the tax rate to find the tax amount?
Because the tax rate applies to the pre-tax price, not the total. If an item costs $100 with 8% tax, the tax is $8 and the total is $108. If you mistakenly multiply $108 × 8% you get $8.64 — wrong. The correct way is: pre-tax = total ÷ (1.08) = $100, then tax = $108 − $100 = $8. This is the most common mistake in manual reverse tax calculations.
Does this reverse tax formula work for VAT and GST?
Yes — VAT (UK, EU), GST (Canada, Australia), and HST (Canadian provinces) all use the same inclusive tax structure. The formula pre-tax = total ÷ (1 + rate) works for all of them. Select your country's rate from the preset dropdown or enter it manually. UK VAT is 20%, Australian GST is 10%, Canadian GST is 5%, Ontario HST is 13%.
What US states have no sales tax?
Five US states have no state sales tax: Oregon, Montana, New Hampshire, Delaware, and Alaska (no state tax, though some Alaska municipalities charge local tax). If you purchased in one of these states, the full amount you paid is the pre-tax price. All other states charge state sales tax between 2.9% (Colorado base) and 7.25% (California base), with combined state + local rates often reaching 9-10%.
How do I find the tax rate if I know the original price and total?
Tax rate = (Total − Pre-tax) ÷ Pre-tax × 100. For example: total $108, pre-tax $100: ($108 − $100) ÷ $100 × 100 = 8%. This is the forward formula — useful when you have a receipt showing both the subtotal and the tax but want to confirm what rate was applied.

References & Sources

  1. [1]
    IRS — Sales Tax Deduction (opens in new tab)

    Supports: Evidence used for reverse sales tax formula — how it works, including related formulas, definitions, or reference values.

    Verified

  2. [2]
    IRS — Sales Tax Deduction Calculator (opens in new tab)

    Supports: Evidence used for how to remove tax from a price (step by step), including related formulas, definitions, or reference values.

    Verified

  3. [3]
    HMRC — VAT Rates (opens in new tab)

    Supports: Evidence used for reverse sales tax formula — how it works, including related formulas, definitions, or reference values.

    Verified

  4. [4]
    Canada.ca — Charge and Collect the GST/HST (opens in new tab)

    Supports: Evidence used for reverse tax calculator for small business bookkeeping, including related formulas, definitions, or reference values.

    Verified