How do I calculate X% of a number?

Convert the percent to a decimal (divide by 100), then multiply by the number. Example: 20% of 150 = 0.20 × 150 = 30. The calculator shows every step.

How is percentage change calculated?

Subtract the original value from the new value, divide by the original, then multiply by 100. A positive result is an increase; a negative result is a decrease.

Can I use this for discounts?

Yes — use the '% of a number' tab to find the discount amount (e.g. 25% of $80 = $20 off), or the change tab to find the percent saved between two prices.

Does this work offline?

Yes. The calculator is pure JavaScript and runs entirely in your browser — no network calls, no tracking, no sign-up.

Filenify

Percentage Calculator

Calculate percentages, discounts, and increases with a visual slider and full step-by-step working shown. Free, instant, no sign-up.

Pick the question you're trying to answer.

Percentage

Of value

Drag to adjust the percentage20%

20% of 15030

Step 1 — Convert percent to decimal20% = 20 ÷ 100 = 0.2
Step 2 — Multiply by the base0.2 × 150 = 30

About Percentage Calculator

Percentage math shows up everywhere — sales discounts, tax rates, tip amounts, grade calculations, financial growth. Filenify's percentage calculator handles the four core operations (X% of Y, what percent X is of Y, percent increase, percent decrease) with a visual slider, live rounding controls, and a full step-by-step working shown alongside each answer. That last part matters: you learn the underlying math while getting the number, so next time you can do it in your head. Great for shoppers checking sale prices, students learning percentage problems, and finance folks running quick sanity checks.

How Percentage Calculator works

1Pick the operation type — percent of, percent from, increase, decrease.
2Enter the two known values in the input fields (or drag the slider).
3See the answer with step-by-step working shown underneath.
4Copy the result or share the URL — it encodes the current calculation.

Frequently asked questions

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