Question 1

How does a percent-off calculator work?

Accepted Answer

Save = original × (off% ÷ 100). Now = original − save. 25% off $80 is $20 off and $60 now. We clamp the off-percent to 0–100 so “150% off” cannot go negative without you noticing.

Question 2

Is “percent off” the same as “percent of”?

Accepted Answer

No. 20% off $50 is a $10 discount (you pay $40). 20% of $50 is $10 as a part, with no “you pay” story. Use this page for sale tags. Use the percentage page for raw parts.

Question 3

How do stacked discounts work?

Accepted Answer

Apply them in order on the remaining price, not by adding the percents. 20% off then 10% off is 0.8 × 0.9 = 28% off, not 30%. This MVP does one percent at a time. Run it twice if a tag is stacked.

Question 4

What about tax on a discounted price?

Accepted Answer

Most US sales tax is on the discounted selling price, not the was-price. Calculate “now,” then take that number to the sales-tax tool. Some jurisdictions differ; we are not your county.

Question 5

Do coupons that say “$10 off” belong here?

Accepted Answer

Not as a percent. Subtract $10 yourself, or treat $10 as the save and skip the percent. A coupon that says “20% off up to $10” is two constraints — compute 20% off, then cap the save at $10.

Question 6

Why does a 50% off then 50% off tag feel like a lie?

Accepted Answer

Because it is 75% off the original, not free. Each 50% is half of what is left. The calculator will happily do each step. Read the tag twice before you pay.

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