Percentages
Percent decrease
The drop over the starting value, scaled to a percentage. The original is always the divisor, never the new value.
The Formula
% Decrease = (Original - New) / Original x 100
The drop over the starting value, scaled to a percentage. The original is always the divisor, never the new value.
| Symbol | Meaning | Unit | Notes |
|---|---|---|---|
| V0 | Original value | number | The figure before the fall, and the quantity that must go in the denominator. |
| V1 | New value | number | The lower figure after the decrease. Must not exceed V0 in an ordinary fall. |
| %D | Percent decrease | percent | Zero when nothing changed, 25.00% for 120 to 90, and capped at 100%. |
What Each Symbol Means
V0number
Original value
The figure before the fall, and the quantity that must go in the denominator.
V1number
New value
The lower figure after the decrease. Must not exceed V0 in an ordinary fall.
%Dpercent
Percent decrease
Zero when nothing changed, 25.00% for 120 to 90, and capped at 100%.
See It Worked With Real Numbers
A formula on its own does not tell you which number goes where. The how to calculate percent decrease page applies this equation to a concrete case, shows every intermediate step, and names the mistakes that produce a wrong answer even when the algebra is right.
Where This Formula Appears
This equation is the working core of How To Calculate Percent Decrease, filed under Math. Every number the guide produces comes from substituting into this one line.