“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 %) ÷ 100Example: 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
Fractions of a yen are usually rounded down at retail stores, so this would be 849 yen. Some stores round to the nearest yen or up - check the register display.
Tax-inclusive vs tax-exclusive
In Japan, discounts usually apply to the tax-exclusive (base) price. The two approaches can differ:
- Discount the base price, then add tax: the common method
- Apply the discount to the tax-inclusive price: simpler, but different math
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.
Enter the list price
Type the price (tax-inclusive or tax-exclusive).
Set the discount rate
Enter 20 for "20% off".
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.
Summary
- Discounted price = list price × (100 − discount %) ÷ 100
- “20% off” simply means paying 80% (multiply by 0.8)
- Fractions are usually rounded down, depending on the store
- 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%.
