Calculate sales drop, current sales, or previous sales from revenue figures and a drop percentage to track changes in dollar sales.
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Drop in Sales Formula
The calculator uses three formulas, one for each mode. Each formula compares sales from a current period to a previous period.
Find drop (percentage decrease):
Drop % = ((Previous - Current) / Previous) * 100
Find current period sales:
Current = Previous * (1 - Drop / 100)
Find previous period sales:
Previous = Current / (1 - Drop / 100)
- Drop %: percentage decrease in sales from one period to the next
- Previous: sales revenue in the earlier period (the baseline)
- Current: sales revenue in the later period
The "Find drop" mode takes both revenue figures and returns the percentage change. A negative result means sales actually went up. The "Find current" mode applies a known drop percentage to a baseline to project where sales landed. The "Find previous" mode works backward from current sales and a drop percentage to recover the original baseline.
Reference Tables
Use the first table to size up how serious a drop is. Use the second to convert between drop percentage and the share of revenue you have left.
| Drop Range | Severity | Typical Cause |
|---|---|---|
| 0% to 5% | Minor | Normal seasonal noise |
| 5% to 10% | Moderate | Pricing or marketing shift |
| 10% to 25% | Notable | Lost customer or new competitor |
| 25% to 50% | Steep | Category decline or supply issue |
| Over 50% | Severe | Market shock or major disruption |
| Drop % | Revenue Retained | Current on $100,000 Previous |
|---|---|---|
| 5% | 95% | $95,000 |
| 10% | 90% | $90,000 |
| 15% | 85% | $85,000 |
| 25% | 75% | $75,000 |
| 40% | 60% | $60,000 |
| 50% | 50% | $50,000 |
Example Problems
Example 1. Last quarter you sold $80,000. This quarter you sold $68,000. Find the drop.
Drop % = (($80,000 - $68,000) / $80,000) * 100 = ($12,000 / $80,000) * 100 = 15%. Sales fell by 15%.
Example 2. Current sales are $42,000 after a reported 16% drop. What were sales before the drop?
Previous = $42,000 / (1 - 16/100) = $42,000 / 0.84 = $50,000.
FAQ
What if the result is negative? A negative drop means sales went up. The calculator flags this as an increase rather than a decline.
Can the drop be 100% or more? No. A 100% drop means sales went to zero, and anything higher is not possible since you cannot lose more revenue than you had. The calculator blocks values of 100 or above when solving for current or previous sales.
Does this work for units sold instead of dollars? Yes. The math is the same for any countable quantity. Enter unit counts in place of dollar amounts and read the result as a percentage change in volume.
Should I compare month over month or year over year? Year over year is usually more reliable because it cancels out seasonality. Month over month is fine for short-term trend tracking but can be misleading for seasonal businesses.
