Work out a sale price from a percent off
“20% off ¥3,980” is easy to misjudge in your head. Get the exact sale price — or work backwards from a tag to the original price.
Tools used in this guide
The job
A tag says “30% off”, or a sign says “was ¥5,980, now ¥4,480”. Two questions come up constantly: what does the discount actually make the price, and is the displayed discount real.
Forward and reverse
Forward mode takes the original price and the percent off and gives the sale price plus the amount saved. Reverse mode takes the sale price and the claimed percent off and gives the original price — useful for checking whether a “50% off” tag is honest about what it was discounted from.
- Two discounts do not add: “20% off then another 10%” is 28% off, not 30%. Run the tool twice to check stacked deals.
- Whether the price on the tag already includes tax changes the answer — check the tag’s convention before comparing.
A worked example
¥3,980 at 20% off → ¥3,184, saving ¥796. If a store advertises “¥3,184, 20% off”, reverse mode gives ¥3,980 as the original — worth a glance when the claimed original looks inflated.