Calculator · Pricing & Margin
Discount Percentage Calculator: % Off, Sale and Original Price
Find the percentage off from an original and a sale price, the sale price after a discount, or the original price behind a sale price — and the dollar amount taken off.
Formula and cost boundary
Discount % = (Original price − Sale price) ÷ Original price; Sale price = Original × (1 − Discount); Original = Sale ÷ (1 − Discount)
Choose what you know. With both prices the calculator returns the percentage off. With the original price and a percentage it returns the sale price. With a sale price and the percentage that was taken off it works backwards to the original — a division, not a multiplication, because the percentage was applied to the original price, not to the sale price. A sale price above the original is rejected: that is a price increase, which the percentage change calculator handles.
Worked examples
| Mode | Inputs | Result | Amount off |
|---|---|---|---|
| Original and sale price | $80 → $60 | 25% off | $20.00 |
| Original price and % off | $49.99 at 30% off | Sale price $34.99 | $15.00 |
| Sale price and % off | $42 after 30% off | Original price $60.00 | $18.00 |
The third row is where mental math goes wrong: adding 30% back to $42 gives $54.60, not $60, because 30% of the sale price is a smaller amount than 30% of the original. Displayed prices are rounded to the cent; $49.99 × 0.70 = $34.993 is shown as $34.99.
What the discount does to margin
A discount comes entirely out of profit, so the margin falls faster than the price. An $80 item that costs $48 has a 40% margin and $32 of profit. At 25% off it sells for $60, keeps $12 of profit and a 20% margin: a quarter off the price removed more than half the profit. The discount margin calculator shows that effect for your own cost, and the stacked discount calculator handles one discount applied on top of another.
How do I calculate percentage off?
Subtract the sale price from the original, divide by the original and multiply by 100. ($80 − $60) ÷ $80 = 25%.
Are two 10% discounts the same as 20% off?
No. The second 10% applies to an already reduced price: 0.90 × 0.90 = 0.81, which is 19% off in total.
Can the discount be 100%?
From an original price, yes — the sale price becomes zero. Working backwards from a sale price, no: nothing can be recovered from a free item.
Method reference: UVM Extension: Markup and Margins. Checked October 26, 2026. Example values are hypothetical.
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