Percent Off Calculator

A percent off is the most common way shops describe a discount. Taking a percent off a product means its price drops by that share of what it was. Fill in any two of the four boxes above and the other two follow, including the case where a coupon stacks on top of a sale price.

How a percent off is worked out

Take a product costing $279 with 20% off. Work out the discount, then take it away from the price.

Discount = original price x percent off / 100
Final price = original price - discount

where:

• original price is the sticker price before anything comes off
• percent off is the advertised discount
• final price is what you hand over at the till

20% of $279 is 0.20 x 279, which is $55.80. Subtract that and the price is $223.20. You save $55.80 and pay $223.20.

There is a shorter route. Paying 20% less is the same as paying 80%, so multiplying straight through skips a step:

Final price = original price x (1 - percent off / 100)

279 x 0.80 gives $223.20 in one move. That form matters once a second discount enters the picture.

Stackable discounts do not add up

A stackable additional discount is a further percent off a price that has already been reduced. The store cuts $279 by 20%, leaving $223.20. Your coupon then takes 15% off, and that 15% applies to $223.20, never to the original $279.

15% of $223.20 is $33.48, so the price lands at $189.72. Total saved is $55.80 plus $33.48, or $89.28. Against the original $279 that is a 32% discount, and not the 35% you get by adding 20 and 15 together.

The multiplier form shows why in one line:

Final price = original price x (1 - first discount) x (1 - second discount)

279 x 0.80 x 0.85 = $189.72. Because 80% of the price is what survives the first cut, and 85% of that survives the second, the share you pay is 0.80 x 0.85, or 68%. The discount is the other 32%.

The gap widens as the numbers get bigger. Two 50% discounts stacked leave 0.50 x 0.50, which is 25% of the price, so 75% off rather than 100%. Nothing free ever comes out of stacking. This is exactly why "extra 20% off sale prices" reads better on a sign than it performs at the till.

Order does not change the outcome

Multiplication does not care which factor comes first, so 279 x 0.80 x 0.85 and 279 x 0.85 x 0.80 both give $189.72. Applying the coupon before the store discount, or after, makes no difference to the total. What does change the answer is sales tax, which is charged on the discounted price, so the tax lands after every discount has been taken off.

Working backwards from the price on the tag

Clearance racks often show the reduced price without saying what the discount was. Two of the four boxes above solve for the rest, so entering an original price of $80 and a final price of $52 returns 35% off and $28 saved.

Percent off = (original price - final price) / original price x 100

Going the other way is just as common. If you know a jacket is 40% off and the tag reads $69, the original price was 69 / 0.60, or $115.

Original price = final price / (1 - percent off / 100)

That second formula is the one worth memorising for shop floors, because it tells you what the retailer was asking before the sale started.

Percent off, percentage points and percentage change

Three different ideas share similar wording. A percent off is a share of a starting price removed from it. A percentage point is the plain difference between two percentages, so a discount going from 20% to 30% is a rise of ten percentage points and also a 50% increase in the discount itself. Percentage change measures movement between two numbers relative to where they started.

The trap sits in reversing a discount. A price cut by 20% needs a 25% rise to return to where it began, because the increase is measured against the smaller number. $100 falls to $80, and $20 on top of $80 is 25%. Retailers who mark up 25% after a 20% sale are back at the original price, not ahead of it.

What the discount is measured against

A percent off means very little on its own, since it is always a share of a reference price that the seller picks. Furniture and mattress retailers have been fined for advertising 60% off a price nothing ever sold at. In the United States the FTC treats a comparison price as deceptive when it is not a real, recent, regular selling price. UK guidance under the Chartered Trading Standards Institute pricing rules expects a reference price to have been the actual price for a meaningful period before the sale.

The practical check is the final price rather than the percentage. Compare what you would pay at three sellers. A 40% discount off $200 and a 25% discount off $160 both cost you $120.

Discounts you meet in ordinary shopping

Buy one get one free is 50% off across two items, since you pay $30 for two $30 shirts and the average is $15 each. Buy two get one free is 33.3% off. A "$20 off $100" voucher is 20% at exactly $100, and it weakens as the basket grows: on a $180 basket the same voucher is 11.1%.

Employee and student discounts usually apply to the sticker price and often cannot be combined with a promotion, so the larger single discount wins. Where they can be combined they stack, which brings you back to multiplying the survivors rather than adding the discounts.

Checking a discount without a calculator

10% is the decimal point moved one place left, so 10% of $46 is $4.60. From there 20% is double that, 5% is half of it, and 15% is the 10% plus the 5%. For $46 at 15% off, that is $4.60 plus $2.30, a $6.90 saving and a final price of $39.10.

25% off is a quarter, so take the price, halve it, halve it again, and subtract. A third off is close enough to divide by three. Rounding the price up to a round number first gets you within a few cents, which is all a shop-floor decision needs.

Rounding at the till

Discounts rarely land on whole cents. $39.99 at 15% off is $33.9915, which the register rounds to $33.99. The calculator above shows the rounded price, so a stacked result can sit a cent away from a longhand calculation that rounds at each step instead of at the end. Retail systems normally round once, on the final line, and that is what is followed here.

Percent off away from the shop floor

Suppliers write early-payment terms as 2/10 net 30, meaning 2% off if the invoice is settled within ten days, with the full amount due in thirty. Two percent for paying twenty days early works out near 36% annualised, which is why finance teams take it whenever cash allows.

Trade and volume discounts stack the same way retail coupons do. A distributor giving 30% off list, then a further 10% for ordering a pallet, is charging 0.70 x 0.90 of list, or 63%, so the discount is 37% and not 40%. Contracts that list several discounts in a row are almost always applied one after another rather than added together, and the wording to look for is "on the net price" rather than "on list".