Percentages and Percentage Change
A percentage of a total, a change relative to an old value, and a difference between two percentages answer three different questions. Identify your baseline before calculating.
Part of a total: divide by the whole
For a share, use part / total × 100. If 25 of 200 responses meet a condition, 25 / 200 × 100 = 12.5%. The total is the denominator; if it is zero, the calculation is undefined.
This is useful for response or conversion shares, not for describing how a value changed over time.
Change: compare the new value with the previous baseline
Utilook calculates percentage change as (new − previous) / abs(previous) × 100. From 80 to 100 the result is +25%; from 100 to 80 it is −20%. Reversing a change does not produce the same magnitude because the baseline changes.
When previous = 0, ordinary percentage change is undefined, and the calculator rejects the input instead of showing infinity. With a negative baseline, the absolute denominator keeps the sign tied to the direction of the numeric change: −100 to −80 is +20%, even though both values remain negative. State the starting value when reporting such a result.
Percentage points are not percentage change
If a conversion rate moves from 20% to 25%, the difference is +5 percentage points, while the relative percentage change is (25 − 20) / 20 × 100 = +25%. Always name the measure you are reporting.
The current Percentage Calculator handles part-of-whole and relative change; it does not offer a separate percentage-point mode. Subtract the two rates yourself when you need that difference.
Processing and interpretation
The calculator runs in the browser; numeric inputs are not sent to Utilook's server or stored by this feature. After a successful calculation, only a tool-use count request is sent without those values.
For a discount, check which price is the baseline. For traffic or sales, state the time period and previous value; a percentage alone can hide how small the original count was.