Percentage Off Calculator

What this calculator does

This calculator answers the two most common percent-off questions a shopper, retailer, or finance analyst needs:

1. Apply a discount — given an original price and a percentage, what’s the final price and how much do I save?
2. Find the original price — given a sale price and the advertised discount, what was the pre-sale price?

Both modes show step-by-step working and a reference table at the five most common discount levels (5 / 10 / 15 / 20 / 25 %) so you can sanity-check a markdown plan or compare two competing tags at a glance.

How to calculate a percent-off discount

saving      = original price × (discount % ÷ 100)
final price = original price − saving
            = original price × (1 − discount % ÷ 100)

The two equivalent forms of the final-price formula matter when you chain operations. The multiplicative form original × (1 − d) is the one to remember, because it composes — you can stack discounts by multiplying their factors, and you can layer tax by multiplying by (1 + tax_rate).

How to find the original price from a sale tag

original price = sale price ÷ (1 − discount % ÷ 100)

The intuition: the sale price is the remaining fraction of the original (e.g. 75 % of the original at a 25 % discount). Dividing by that fraction recovers the full 100 %. This is the most useful trick for reading store tags — given a sale price and a percent-off badge, you can immediately see the implied original even when it’s not on the label.

Worked example

A pair of shoes is on sale at 25 % off an $80 list price:

Reversed: a sale tag of $60 with “25 % off” means the original was:

Same two numbers, opposite direction.

Stacked discounts — they multiply, they don’t add

The “extra X % off at checkout” pattern is everywhere, and it’s designed to make a discount feel bigger than it is. The rule:

total kept fraction = (1 − d1) × (1 − d2) × …
total discount     = 1 − (kept fraction)

Two 50 % markdowns never give you the item for free — they leave you paying 25 % of the original. This is also why “100 % off” campaigns are nearly always actually “buy one get one” — true 100 % off would be unbounded loss on the seller’s side.

Discount + tax: order of operations

In most countries, sales tax / VAT applies to the discounted price, not the original. The composed formula:

total = original × (1 − discount/100) × (1 + tax_rate/100)

Example: an $80 item with 25 % off and 8 % sales tax → 80 × 0.75 × 1.08 = $64.80. A handful of US states historically taxed the pre-discount amount for “manufacturer coupons” (vs “store coupons”); that’s a niche edge case to confirm locally if you sell or buy across state lines.

Common mistakes to avoid

Adding stacked discounts. Two 25 % markdowns are not 50 % off — they’re 43.75 % off (0.75 × 0.75 = 0.5625, so 1 − 0.5625 = 43.75 %).

Dividing the saving by the sale price. “I saved $20 on a $60 sale” reads as 33.3 % off the sale price, which is the wrong base. The advertised discount is always relative to the original price, not the discounted one. ($20 saving on an original $80 = 25 % off.)

Forgetting tax order. Calculating tax on the original and then subtracting the discount usually understates the saving, because the discount applies to the larger number. Always discount first, tax second.

Misreading “70 % off” vs “70 % of original”. “70 % of the original price” means you pay 70 %, so the discount is 30 %. “70 % off” means you pay 30 %. The preposition is the entire difference.

Privacy

This calculator runs as a few arithmetic operations in JavaScript on your device. There are no fetch calls, no analytics on the values you enter, no server-side logging.