Enter the price and discount
How to use the discount calculator, and how to read a sale
"30% off" or "500 yen off" is hard to work out in your head, and comparing two offers with different structures is harder still. Enter the original price and the discount, and this tool shows the sale price, the saving and the effective discount rate together.
How to use it
Enter the original price, choose the discount type (% off or amount off) and type the value. Choosing amount off also reveals what percentage that saving represents, so "1,000 yen off" and "25% off" can be compared on the same scale.
Stacked discounts do not add up
A common trap: 20% off followed by a further 10% at the till is not 30% off. The first step multiplies by 0.8 and the second by 0.9, giving 0.72 — that is 28% off. The gap from naive addition widens with every extra step. To check a second stage here, take the first result and re-enter it as the original price.
A discount and points back are not worth the same
"20% off" means you pay 80% today. "20% points back" means you pay the full price and receive points worth 20% for a future purchase. Points expire and are often restricted to certain shops, so unused value simply evaporates. If the goal is to spend less today, the discount wins. To convert a points rate into an equivalent discount, the usual approximation is rate ÷ (1 + rate), assuming you definitely spend the points.
What is "second item half price" worth overall?
Buying two and getting the second at half price means paying 75% of two full prices — 25% off overall. "Third one free" works out at three for the price of two, about 33% off. Neither helps if you only wanted one.
Tax and rounding
Whether the shelf price includes tax changes the final figure. Most Japanese retailers apply the discount to the pre-tax price and then add consumption tax, but some discount the tax-inclusive price directly, and rounding rules differ by shop. This tool rounds to the nearest yen. For tax conversion see the consumption tax calculator, and for plain ratios the percentage calculator.
Frequently asked questions
How is the sale price calculated?+
The savings and effective rate are also shown.
Is 20% off the same as 20% points back?+
The discount is cheaper at the register.
What is the effective discount rate?+
It tells you what percentage a fixed amount-off actually represents.
How is rounding handled?+
Real stores may round down or handle fractions differently.
Are my inputs stored?+
・Sale price (% off) = original × (1 − rate)
・Sale price (amount off) = original − amount
・Effective rate = discount ÷ original × 100. Stacked discounts multiply as (1 − r1) × (1 − r2); the rates do not add.
・Displayed values are rounded to the nearest unit (store rounding may differ)
・Act against Unjustifiable Premiums and Misleading Representations (Japan), Art. 5(ii): prohibition of representations that mislead consumers into believing terms are far more advantageous than they are
・Consumer Affairs Agency, Japan. Guidance on price representations: a reference price used in dual pricing must be one at which the item was actually sold for a substantial recent period
This site does not represent any store or business and does not guarantee the accuracy of the results. Rounding, stacking and coupon eligibility vary by store. Confirm the actual price at the register and the store's conditions.