“A 2,980 yen item is 20% off” or “everything is 30% off” - do you struggle with the math at every sale?

In this article, we explain how to calculate discounts, covering the percent-off formula, common discount examples, and the tax-inclusive vs tax-exclusive difference, with concrete numbers.

The percent-off formula

The discounted price is:

Discounted price = list price × (100 − discount %) ÷ 100

Example: a 2,980 yen item at 20% off

  • 2,980 × (100 − 20) ÷ 100 = 2,384 yen

To find the savings instead:

Savings = list price × discount % ÷ 100
  • 2,980 × 20 ÷ 100 = 596 yen

Tip: Think in terms of what remains. 20% off means paying 80% of the price - just multiply by 0.8.

Common discount examples

Discount Formula Example (3,000 yen)
10% off price × 0.9 2,700 yen
20% off price × 0.8 2,400 yen
30% off price × 0.7 2,100 yen
40% off price × 0.6 1,800 yen
50% off price × 0.5 1,500 yen

What about fractions?

Example: a 999 yen item at 15% off

  • 999 × 0.85 = 849.15 yen

If a store rounds down, this is 849 yen. Other rounding methods are possible; check the terms and checkout amount.

Tax-inclusive vs tax-exclusive

Check the store terms for the discount base. With the same percentage applied to the whole price and no intermediate rounding, these methods give the same result:

  • Discount the base price, then add tax: base-price calculation
  • Apply the discount to the tax-inclusive price: the same multiplication in another order

Example: 3,300 yen including tax (3,000 yen base) at 10% off

Method Result
10% off base price, then add tax 3,000 × 0.9 = 2,700 + 270 tax = 2,970 yen
10% off the tax-inclusive price 3,300 × 0.9 = 2,970 yen

In this example the results match, but rounding can create small differences. Always check whether “% off” applies to the tax-inclusive or tax-exclusive price.

Caution: Whether "% off" applies to the tax-inclusive or tax-exclusive price varies by store. On online shops, confirm the final amount before checking out.

Stacking coupons and multiple discounts

Some stores let you combine a storewide sale with a coupon. Be careful: most shops apply them one at a time, not additively.

Example: a 5,000 yen item with “30% off” and a “1,000 yen off” coupon

  • Applied one after another: 5,000 × 0.7 = 3,500, then 3,500 − 1,000 = 2,500 yen
  • Some promotions apply the coupon first: (5,000 − 1,000) × 0.7 = 2,800 yen

The order changes the result. Always check the store’s terms, and when a percentage and a fixed amount are both involved, the calculation tool helps you verify each step.

How to calculate a discount

With the Tools Hub discount calculator, enter the list price and discount rate and the savings and final price appear instantly.

1

Enter the list price

Type the price (tax-inclusive or tax-exclusive).

2

Set the discount rate

Enter 20 for "20% off".

3

Read the result

The savings and the discounted price are shown together.

The tool introduced in this article

Discount Calculator

Calculate from the discount rate or the savings amount. All in your browser with no uploads.

Calculate now

Summary

  • Discounted price = list price × (100 − discount %) ÷ 100
  • “20% off” simply means paying 80% (multiply by 0.8)
  • Rounding depends on the store terms
  • Check whether the discount applies to the tax-inclusive or tax-exclusive price
  • The Tools Hub calculator handles it all in your browser

Next time you face a sale or coupon, use the formulas above or the Tools Hub discount calculator.

FAQ

How do I calculate 20% off?

Multiply the price by 0.8. Example: 3,000 yen × 0.8 = 2,400 yen.

Is 2割引 (20% off in Japanese) the same as 20% off?

Yes. Both mean you pay 80% of the list price.

Can I apply the discount to a tax-inclusive price?

It depends on the store. Discounting the tax-inclusive price can give a slightly different result than discounting the base price and adding tax.

How do I find the discount rate from the savings?

Divide the savings by the list price and multiply by 100. Example: 600 yen off 3,000 yen is 600 ÷ 3,000 × 100 = 20%.