What is reverse sales tax?
Reverse sales tax is the arithmetic that turns a tax-included total back into the price before tax. You have a receipt for $107.25, the store charged 7.25%, and the item itself cost $100.00 — the remaining $7.25 was tax. The Reverse Sales Tax Calculator does that in one direction only: you type the total and the rate, and it hands back the pre-tax price, the tax amount, and the division it used to get there.
Going forwards is the calculation everyone learns. Price, add tax, done. Going backwards is the one people actually need at 9pm with a shoebox of receipts and an expense form that wants the price on one line and the tax on another. It also shows up in bookkeeping, where the tax portion of a business purchase is tracked separately from the expense, and in pricing, where you want to know what shelf price lands a customer at a round $20 out the door.
People search for this under half a dozen names — working backwards from a total, a sales tax decalculator, or simply how to remove sales tax from a total. Whatever you call it, the operation is a division, not a subtraction — and that distinction is where most of the wrong answers come from. A $1,593.75 total at 6.25% comes back to exactly $1,500.00, with $93.75 of tax. Subtract 6.25% from the total instead and you get $1,494.14, which is $5.86 short and will not reconcile against anything.
How to use the Reverse Sales Tax Calculator
Two boxes and a dropdown. There is no Calculate button on this page, which sounds like a small thing until you compare it to the alternative — the answer appears while you are still typing.
- Type the total from the receipt — the amount you actually paid, tax included. A leading dollar sign is fine; so is a comma in the thousands.
- Pick your state from the dropdown to fill in its combined state-plus-average-local rate, or skip straight to the rate box and type the exact rate printed on the receipt. The receipt always wins — presets are averages, and your city can sit more than a point away from its state's.
- Read the price before tax. It is the large green figure. The tax amount sits underneath with the rate echoed next to it, and the total is repeated so you can check you typed it correctly.
- Check the worked division below the breakdown. It shows your total, the divisor used, and the answer —
1,593.75 ÷ 1.0625 = 1,500.00— with your own numbers in it, not a static example. - Press Copy breakdown for a single line you can paste into a spreadsheet cell or a reimbursement note:
Pre-tax $1,500.00 + Tax $93.75 = Total $1,593.75 (6.25%).
Leave either box empty and nothing appears — no $0.00 placeholder, no "enter a value to begin" nag. Type something that isn't a number and the result simply stays hidden rather than flashing NaN at you.
The formula behind the pre-tax price
One line of math runs the whole Reverse Sales Tax Calculator.
Pre-tax price = total ÷ (1 + rate ÷ 100)
The total is what you paid. The rate is the combined sales-tax percentage that was applied — 6.25 for 6.25%, not 0.0625. Dividing by 1 + rate ÷ 100 undoes the multiplication the register did on the way in, because the register multiplied the pre-tax price by that same figure.
Work through the $1,593.75 receipt at 6.25%. The divisor is 1 + 6.25 ÷ 100 = 1.0625. Then 1,593.75 ÷ 1.0625 = 1,500.00. The tax is what's left: 1,593.75 − 1,500.00 = 93.75. Check it forwards — 1,500.00 × 1.0625 = 1,593.75 — and you are back where you started.
A second example, with a rate that isn't a neat fraction. A $128.94 total in Texas at 8.20% divides by 1.082 to give $119.17, leaving $9.77 of tax. And a zero-rate state is not a special case, just a boring one: a $49.99 total in Oregon divides by 1, so the pre-tax price is $49.99 and the tax line reads $0.00.
One detail matters more than it looks. The tax figure here is derived as the remainder — total minus the rounded pre-tax price — rather than calculated and rounded on its own. Round both independently and roughly one row in fifty comes out a cent off, so the three numbers on screen don't add up. That is fine until a bookkeeper reconciles it. Here the displayed pre-tax price plus the displayed tax equals the displayed total on every single calculation, at $9.99 and at $9,999,999.99 alike.
Why subtracting the tax percentage gets the wrong answer
This is the single most common error in reverse tax math, and it is worth seeing rather than being told. The instinct is that if 8% was added, taking 8% off gets you home. It doesn't, because the 8% was charged on the smaller number — the pre-tax price — and you'd be taking it off the larger one.
| Total paid | Rate | Subtract the % (wrong) | Divide (right) | Off by |
|---|---|---|---|---|
| $108.00 | 8.00% | $99.36 | $100.00 | $0.64 |
| $54.18 | 8.85% | $49.39 | $49.77 | $0.38 |
| $63.47 | 9.55% | $57.41 | $57.94 | $0.53 |
| $250.00 | 8.85% | $227.88 | $229.67 | $1.79 |
| $1,000.00 | 7.02% | $929.80 | $934.40 | $4.60 |
| $1,593.75 | 6.25% | $1,494.14 | $1,500.00 | $5.86 |
The error always points the same way: subtracting undershoots the true pre-tax price, never overshoots it. And it scales with both the amount and the square of the rate — the gap is roughly total × rate² ÷ (1 + rate). On a $50 lunch it's a rounding-error 38 cents and nobody notices. On a $1,000 equipment purchase at a 7% rate it's $4.60, which is exactly the kind of number that shows up as an unexplained variance three weeks later.
What common state rates do to a $100 total
A quick reference for the shape of the answer. Each row is a $100.00 tax-included total split back into its two parts, using that state's combined state-plus-average-local rate.
| State | Combined rate | Divisor | Price before tax | Tax |
|---|---|---|---|---|
| Alabama | 9.25% | 1.0925 | $91.53 | $8.47 |
| Alaska | 1.81% | 1.0181 | $98.22 | $1.78 |
| California | 8.85% | 1.0885 | $91.87 | $8.13 |
| Delaware | 0.00% | 1 | $100.00 | $0.00 |
| Florida | 7.02% | 1.0702 | $93.44 | $6.56 |
| Louisiana | 9.55% | 1.0955 | $91.28 | $8.72 |
| Massachusetts | 6.25% | 1.0625 | $94.12 | $5.88 |
| New York | 8.53% | 1.0853 | $92.14 | $7.86 |
| Oregon | 0.00% | 1 | $100.00 | $0.00 |
| Texas | 8.20% | 1.082 | $92.42 | $7.58 |
| Tennessee | 9.55% | 1.0955 | $91.28 | $8.72 |
| Washington | 9.40% | 1.094 | $91.41 | $8.59 |
The spread is wider than most people expect. The same $100 in hand buys $100.00 of goods in Oregon and $91.28 in Louisiana — an $8.72 difference on a single small purchase. Alaska is the interesting row: it has no statewide sales tax at all, but its boroughs and cities charge their own, which averages out to 1.81%, so its preset is not zero the way Delaware, Montana, New Hampshire and Oregon are.
These presets are combined state plus average local rates, and they drift every January. Your actual rate depends on the address the sale happened at — in Louisiana and Colorado the spread between cities runs well over two points. Use a preset when the receipt isn't in front of you, and type the printed rate when it is.
Edge cases and limitations
A receipt total is a single number hiding a lot of structure, and reverse tax math assumes that structure is simple. Sometimes it isn't.
Mixed receipts
This is the big one. If a receipt contains both taxable and exempt items — groceries and household goods in the same basket, or prescriptions alongside cosmetics — there is no single rate that describes the whole total. Reversing the full amount at the general rate will be wrong for every line. Split the receipt by tax group and reverse each group separately.
Charges added after tax
Tips, delivery fees and service charges are often applied after tax is calculated, so they sit on top of the taxed portion rather than inside it. Strip those out before you reverse. The same goes for excise taxes already baked into a shelf price — fuel, alcohol, hotel occupancy — which are not sales tax and won't come out with this division.
Register rounding
Some merchants calculate tax per line item and some per order, and the two approaches can land a cent apart on a long receipt. If your reversed figure differs from the register by $0.01, that's usually why, and it's not worth chasing.
The Reverse Sales Tax Calculator also refuses some inputs by showing nothing at all: rates outside 0–30% and negative totals get no result, on purpose, because a 45% sales tax is a typo rather than a jurisdiction. And none of this is tax advice — for a filing position, a return or an audit, talk to an accountant.
Related calculations
Going the other direction — you have a price and want to know the out-the-door total — is the Sales Tax Calculator, which carries the same 51 rate presets. The two pages do one job each rather than sharing a mode toggle you have to answer before you can start typing.
Outside the US, the equivalent question is usually about VAT or GST. The arithmetic is identical, but the VAT Calculator has UK, EU, Australian, New Zealand and Canadian presets and handles both directions, so it'll be less work.
Two more that live in the same part of a receipt: the Discount Calculator, for working out what a percentage off actually leaves you paying, and the Tip Calculator, which tips on the pre-tax subtotal if you ask it to. For everything else percentage-shaped — what's 8.25% of $340, what percent is 17 of 240 — the Percentage Calculator covers it.
Frequently asked questions
How do I calculate the price before tax from a total?
Divide the total by 1 plus the rate as a decimal. At 6.25% that's total ÷ 1.0625, so a $1,593.75 total comes back to $1,500.00 with $93.75 of tax. The Reverse Sales Tax Calculator shows that division with your own numbers in it, underneath the answer.
Why can't I just subtract the tax percentage from the total?
Because the tax was charged on the pre-tax price, not on the total. Taking 8% off a $108.00 total gives $99.36, but the real pre-tax price was $100.00. The gap grows with the amount and with the square of the rate, and it always errs in the same direction — subtracting undershoots.
Which rate should I use — the state preset or the one on my receipt?
The receipt, every time. The presets here are the state base rate plus an average of local city and county rates, and your actual rate depends on where the sale happened. Use a preset when you don't have the receipt in front of you, and treat it as an estimate when you do.
Do the pre-tax and tax figures always add back to the total?
Yes, to the cent, on every calculation. The pre-tax price is rounded once and the tax is whatever remains, so the three figures on screen always sum correctly. Calculators that round both independently put a one-cent discrepancy on roughly one row in fifty.
What about states with no sales tax?
Delaware, Montana, New Hampshire and Oregon have no statewide sales tax, so the pre-tax price equals the total, the tax line reads $0.00 and the formula divides by 1. Alaska is the exception that looks like a rule: no statewide rate, but local jurisdictions charge their own, averaging about 1.81%.
Can I use this for VAT or GST?
The arithmetic is identical — divide by 1 plus the rate — so it works for any single-rate tax already included in a price. If you're working in VAT terms the VAT Calculator will fit better, since it carries the relevant country presets. Indian GST splits into CGST and SGST components that this page doesn't break out.
Is this free, and is anything I type here saved?
It's free, there's no account, and the whole calculation runs in your browser — nothing is stored, nothing is transmitted, and closing the tab clears it. No Calculate button gating the answer, no trial countdown, no moment where the result appears and then asks you to open it in an app to see the working. Microapp gives 10% of every dollar it earns to charity, off the top and audited quarterly, which is the part of the business model that isn't your problem.