Double Discount Calculator
Multiply the original price by (1 - d1)(1 - d2) to find the real checkout price, total savings, and equivalent single discount for a stacked promotion before you assume the headline percentages add directly.
Discount Inputs
Quick Scenarios
Discount Summary
Compare the real final price with the headline percentage stack before you treat the deal as one large markdown.
Final price after 2 discounts
$72.00
A 20.00% + 10.00% stack on $100.00 leaves a final price of $72.00 and a true equivalent discount of 28.00%.
Equivalent single discount
28.00%
Total savings
$28.00
You pay
72.00%
Gap vs simple addition
2.00%
Detailed Breakdown
| Metric | Value |
|---|---|
| Original price | $100.00 |
| First discount rate | 20.00% |
| First discount savings | $20.00 |
| Price after first discount | $80.00 |
| Second discount rate | 10.00% |
| Second discount savings | $8.00 |
| Price after second discount | $72.00 |
| Final price | $72.00 |
| Equivalent single discount | 28.00% |
| Simple added discount | 30.00% |
| Gap vs simple addition | 2.00% |
| You pay | 72.00% |
Stage-by-Stage Read
First discount
20.00% on $100.00 saves $20.00, leaving $80.00.
Running total: $20.00 saved, or 20.00% off.
Second discount
10.00% on $80.00 saves $8.00, leaving $72.00.
Running total: $28.00 saved, or 28.00% off.
Current Calculation Check
Final price math
Final price = $100.00 x 0.8000 x 0.9000 = $72.00
Equivalent discount math
Equivalent discount = 1 - (0.8000 x 0.9000) = 28.00%
Simple addition check
Simple addition = 20.00% + 10.00% = 30.00%
Actual discount is 28.00%, so the headline sum overstates the deal by 2.00%.
Editorial & Review Information
Reviewed on: 2026-03-17
Published on: 2025-12-03
Author: LumoCalculator Editorial Team
What we checked: Double-discount formula math, example arithmetic, simple-sum comparison, optional third-discount behavior, and source accessibility.
Purpose and scope: This page helps users compare stacked percentage promotions and vendor discount ladders. It is not a tax, shipping, or retailer-policy engine.
How to use this review: Enter the real order of percentage discounts, compare the equivalent single discount with alternate offers, and check store rules before assuming every advertised percentage can actually stack.
Use Scenarios
Retail promo audit
Check whether a sale price plus one extra coupon really beats a cleaner single markdown before you commit to the offer.
Two-step vs three-step comparison
If the promotion truly has three stable percentage layers, compare it with the Triple Discount Calculator instead of pretending the extra step does not matter.
Vendor quote review
Convert a two-step supplier concession into one comparable percentage before you line up competing quotes that use different discount language.
Formula Explanation
1) Final price comes from multiplying the remaining factors
Final price = Original price x (1 - d1) x (1 - d2)
Each percentage discount is applied to the reduced running price, so the second discount always works on a smaller base than the first one.
2) Equivalent single discount is the cleanest comparison tool
Equivalent discount = 1 - (1 - d1)(1 - d2)
This turns the whole stack into one comparable percentage, which is the easiest way to judge a layered promotion against a single markdown elsewhere.
3) Simple addition is a headline, not the real result
Simple sum = d1 + d2
The added headline percentage is useful only as a rough comparison. The calculator shows the gap between the headline sum and the true equivalent discount so the deal is not overstated.
How to Read the Result
Final price
This is the actual checkout price after every percentage in the stack has been applied in order.
Equivalent single discount
Use this number when comparing one stacked deal with another store's clean single markdown.
Gap vs simple addition
This shows how much the headline added percentages overstate the real discount once the shrinking price base is respected.
You pay
The remaining payment share is useful when you need to decide whether the stack still leaves enough room for margin or whether a simpler promotion would do the same job.
Common Promotion Pairs
| Context | Stack | Equivalent discount | Planning note |
|---|---|---|---|
| Light coupon pair | 10% + 10% | 19.00% | Two small percentages still land below a clean 20% markdown. |
| Common retail stack | 20% + 10% | 28.00% | This is the classic example that shows why the second discount hits a smaller base. |
| Clearance pair | 30% + 20% | 44.00% | A headline 50% stack behaves like a 44% single discount instead. |
| Aggressive pair | 50% + 25% | 62.50% | A dramatic-sounding pair still leaves 37.50% of the original price to pay. |
| Optional third step | 25% + 10% + 5% | 35.88% | A final app or card bonus helps, but it does not add a full five points to the total discount. |
Example Cases
Case 1: Weekend apparel deal
Inputs
- Original price: $100
- Discounts: 20%, 10%
- Optional third discount: Off
Computed Results
- Final price: $72.00
- Total savings: $28.00
- Equivalent single discount: 28.00%
Interpretation
The stack sounds like 30% off, but the real offer behaves like a 28% markdown.
Decision Hint
Compare this directly with any single offer close to 28% to 30% before choosing the layered deal.
Case 2: Clearance plus loyalty
Inputs
- Original price: $240
- Discounts: 35%, 15%
- Optional third discount: Off
Computed Results
- Final price: $132.60
- Total savings: $107.40
- Equivalent single discount: 44.75%
Interpretation
A headline 50% stack does not materialize here because the loyalty percentage is applied after the first markdown.
Decision Hint
Use the 44.75% equivalent rate when comparing this promo with a single 45% alternative.
Case 3: Checkout bonus added
Inputs
- Original price: $320
- Main discounts: 25%, 10%
- Third discount: 5% app reward
Computed Results
- Final price: $205.20
- Total savings: $114.80
- Equivalent single discount: 35.88%
Interpretation
The final 5% helps, but it does not add a full five points to the total discount because it hits a reduced base.
Decision Hint
Switch on the optional third field only when the extra reward truly applies after the first two stages.
Boundary Conditions
Sources & References
- Omni Calculator - Double Discount Calculator - Formula framing, worked examples, and equivalent-discount comparison cues for a two-step stack.
- Ultimate Finance Calculator - Double Discount Calculator - Concise calculator-first positioning, final-price language, and stacked-savings terminology.
- Calculator.net - Discount Calculator - General discount formula reference and example-style price-versus-savings comparison structure.