How to Calculate Discounts and the Final Price
Sales are designed to feel like savings. A little arithmetic tells you what you are really paying — and whether '50% + 20% off' is as good as it sounds.
By ToolJolt Team · May 24, 2026
The basic discount
Final price = original × (1 − discount/100). A 30%-off item at 200 costs 200 × 0.70 = 140. The amount saved is original × discount/100 = 60. That is every single-discount problem solved.
Stacked discounts don't add
'50% then 20% off' is not 70% off. You take 50% off (leaving 50%), then 20% off that (leaving 80% of 50% = 40%). So the real discount is 60%, and you pay 40% of the original. Stacked percentages always multiply, never add.
Is the deal actually good?
- Compare the final price to the genuine usual price, not the inflated 'was' price.
- Check the unit price — a bigger pack at a discount can still be worse value.
- Factor in shipping and returns, which can erase a small saving.
Reverse it: what was the original?
If a tag says 'now 140, 30% off', the original was 140 ÷ 0.70 = 200. Dividing by (1 − discount) recovers the starting price — handy for spotting fake markdowns.
Calculate instantly
ToolJolt's discount calculator gives the final price and savings at a glance, and the percentage calculator covers the trickier reverse and change problems.
Free tools mentioned in this guide
Frequently asked questions
How do I calculate a sale price?
Multiply the original price by (1 − discount/100). For 30% off, multiply by 0.70.
Does 50% + 20% off equal 70% off?
No. The discounts multiply: you pay 80% of 50% = 40% of the original, which is a 60% total discount.
How do I find the original price from a sale price?
Divide the sale price by (1 − discount/100). A 140 price at 30% off came from 140 ÷ 0.70 = 200.