Discount Calculator
Apply single or stacked discounts and see the final price and amount saved.
About Discount Calculator
The sale price is the original price minus the discount percentage. A stacked coupon applies on top of the already-reduced price, so two 20% discounts give 36% off in total — not 40%.
Formulas
Single discount
Sale price = Original price × (1 − discount)
- P
- Original price
- d₁
- Primary discount as a decimal (e.g. 0.25 for 25%)
- P_sale
- Final sale price
Stacked coupon
Sale price = Original price × (1 − first discount) × (1 − extra coupon)
- d₂
- Extra coupon as a decimal — applied on top of the already-reduced price
Worked example
With the default values below, Discount Calculator returns Final Price of $90.00. Change any input above and every figure here is recalculated in your browser.
Inputs used
- Original Priceaccepts 0–1,000,000 $
- 120 $
- Discountaccepts 0–100 %
- 25 %
- Extra Coupon (stacked)accepts 0–100 %
- 0 %
Results
- Final Price
- $90.00
- You Save
- $30.00
- Effective Discount
- 25.0%
Step by step
- 1Original price= $120.00
- 2Apply primary discount= $90.00
- 3Amount saved= $30.00
- 4Effective discount percentage= 25.0%
Assumptions and limits
- The result is derived only from the 3 inputs listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
- Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
- This is an estimate for general information and not professional financial, tax or legal advice. See the full disclaimer for the limits that apply to this kind of calculator.
How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.
Discount Calculator — full guide
The two questions shoppers actually have
What will this cost at the register, and is the second coupon worth as much as the sign implies? Both are the same calculation. The calculator takes Original Price (default 120), Discount % (default 25) and Extra Coupon (stacked) % (default 0), and returns the final price, the amount saved and the effective discount.
Single discount
Multiply by what is left, not by what is taken off:
- Final price = price × (1 − discount) = 120 × 0.75 = 90
- You save = 120 − 90 = 30
The "multiply by what remains" habit is the whole trick. 25% off means you pay 75%, so one multiplication gets you there with no subtraction step to fumble.
Stacking a coupon
A second discount applies to the already-reduced price, so the two percentages multiply rather than add. Put 25 in the discount field and 10 in the extra coupon field:
- After the first cut: 120 × 0.75 = 90
- After the coupon: 90 × 0.90 = 81
- Saved: 120 − 81 = 39
- Effective discount: 1 − (0.75 × 0.90) = 0.325, so 32.5%
Not 35%. The coupon's 10% is taken off 90, which is 9, not off 120, which would be 12. The gap widens with bigger numbers — two 20% discounts give 36% off, not 40%, because 0.80 × 0.80 = 0.64.
| Advertised | Effective | Price from 120 |
|---|---|---|
| 25% then 10% | 32.5% | 81 |
| 20% then 20% | 36% | 76.80 |
| 50% then 20% | 60% | 48 |
Order does not matter
Multiplication commutes, so 10% first then 25% also lands on 81. If a till applies them in a different sequence than you expected, the final price is unchanged. What does change the answer is mixing a percentage with a flat amount — a flat 20 off before a 25% cut is not the same as after it.
Limits and traps
- The result is pre-tax. Add tax afterwards with the sales tax calculator — 81 at 8.25% becomes 87.68.
- "Up to 70% off" describes the best item in the sale, not yours.
- A discount from an inflated reference price saves less than the percentage suggests, so compare the final figure against what you have actually seen the item sell for.
- Both fields take percentages. For a flat coupon, convert first: 15 off 120 is 12.5%.
Use the percentage calculator for the underlying arithmetic, or the margin calculator if you are the seller and need to know what the markdown leaves you.
Frequently Asked Questions
Do stacked discounts add up?
No. A 20% discount followed by another 20% coupon multiplies (0.8 × 0.8 = 0.64), which is 36% off, not 40%. The 'effective discount' figure shows the true combined savings.
Does this include sales tax?
No — this is the pre-tax price. Use the Sales Tax calculator to add tax to the final price.
The sign says 'extra 10% off already-reduced prices' — which field does each number go in?
The rack discount goes in Discount % and the register coupon goes in Extra Coupon %. For a 120 item marked 25% off with an extra 10% at the till, enter 120, 25 and 10 to get 81. Entering 35 as a single discount would show 78, which is 3 less than you will actually pay.
What single discount is equivalent to 25% plus a 10% coupon?
32.5%, which is the effective discount the calculator reports: 1 − (0.75 × 0.90) = 0.325. That single figure is what you should use when comparing against a competitor's flat offer. A straight 35% off beats the stacked pair, taking the 120 item to 78 instead of 81.
Can I use this for a flat amount off, like 15 off?
Not directly — both fields are percentages. Convert the flat amount first by dividing it by the price it applies to: 15 off 120 is 12.5%. If the flat coupon comes after a percentage markdown, divide by the reduced price instead, so 15 off a 90 sale price is 16.67%.
How do I check whether a bigger pack is better value than a discounted small one?
Work out each final price here, then divide by the quantity. A 120 pack of 12 at 25% off costs 81, or 6.75 a unit. A 45 pack of 6 at 10% off costs 40.50, or 6.75 a unit — identical, so buy whichever quantity you will actually use.