Calculate decay percentage, total decay, or original starting amount by entering any two values, with results in units, thousands, or millions.
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Decay Percentage Formula
The decay percentage calculator uses the relationship between the original starting amount, the decay percentage, and the total decay amount.
TD = OA * (DP/100)
DP = (TD/OA) * 100
OA = TD / (DP/100)
- TD = total decay
- OA = original starting amount
- DP = decay percentage
If you enter the original starting amount and the decay percentage, the calculator finds the total decay. If you enter the original amount and total decay, it finds the decay percentage. If you enter the decay percentage and total decay, it finds the original starting amount.
The unit menus convert values between units, thousands, and millions before calculating. For example, 2 millions is treated as 2,000,000 units.
Decay Percentage Reference Values
Use these values to quickly check what a decay percentage means as a fraction or decimal of the original amount.
| Decay Percentage | Decimal Form | Fraction of Original Lost |
|---|---|---|
| 1% | 0.01 | 1/100 |
| 5% | 0.05 | 5/100 |
| 10% | 0.10 | 10/100 |
| 25% | 0.25 | 25/100 |
| 50% | 0.50 | 50/100 |
Unit Conversion Used in the Calculator
| Selected Unit | Base Unit Value | Example |
|---|---|---|
| Units | 1 | 500 units = 500 |
| Thousands | 1,000 | 500 thousands = 500,000 |
| Millions | 1,000,000 | 2 millions = 2,000,000 |
Example Problems
Example 1: Find total decay
You start with 800 units and the decay percentage is 15%.
TD = 800 * (15/100)
TD = 120
The total decay is 120 units.
Example 2: Find decay percentage
The original starting amount is 2,000 units and the total decay is 300 units.
DP = (300/2000) * 100
DP = 15
The decay percentage is 15%.
FAQ
What does decay percentage mean?
Decay percentage is the percent of the original amount that has been lost, reduced, or removed. For example, if an item starts at 1,000 units and decays by 20%, the total decay is 200 units.
Is total decay the same as the remaining amount?
No. Total decay is the amount lost. The remaining amount is what is left after the decay. To find the remaining amount, subtract the total decay from the original starting amount.
Remaining\ Amount = OA - TD
Can the decay percentage be more than 100%?
Mathematically, the calculator can compute percentages above 100% if the total decay is greater than the original amount. In most real situations, a decay greater than 100% means the inputs should be checked, because an amount usually cannot lose more than its full starting value.
