Percentage Calculator

Relative change divides by the baseline. If the baseline is tiny, the same absolute jump looks like a massive percentage swing—mathematically correct but misleading for business headlines. Report absolute deltas alongside percentages, or use a different baseline when crossing zero.

Each calculator block is independent: “X% of Y” is a single multiplication, not successive compounding. For year-over-year stacks or chained tax-on-tax, model the sequence explicitly in a spreadsheet—order of operations matters.

Floating point in browsers inherits IEEE quirks; for currency, many teams round per line item or per tax bracket per local law. Use this tool for quick mental checks; push final cents into an accounting engine with decimal types.

“Percent of” still multiplies signed values; “part is what percent of whole” rejects a zero whole but allows negative parts (interpret carefully). Percent change uses `abs(old)` in the denominator to avoid sign flips—verify against your finance team’s convention for losses.

No. These are deterministic arithmetic helpers. Confidence intervals and sample percentages need statistical tooling, not a three-field form.

Small ratios (conversion rates) need precision before marketing rounds them to one decimal. You can truncate for display, but copying raw avoids accumulated rounding errors in downstream slides.