Percentage Calculator

Four percentage modes in one compact view

UtilitiesFREEYour data never leaves your browser

100% freeNo signupRuns in your browser

Built by WOWHOW Team · 14+ yrs engineering

Percentage Calculator is a free, browser-based tool that lets you four percentage modes in one compact view — with zero signup, zero installation. Your data never leaves your browser. Part of 138+ free developer and business tools at wowhow.cloud, built and maintained by a team with 14+ years of hands-on development experience.

TOOLPercentage Calculator

What is X% of Y?

Percentage (X%)

Number (Y)

X is what % of Y?

Number (X)

Total (Y)

% Change from X to Y

From (X)

To (Y)

X + Y% / X - Y%

Number (X)

Percentage (Y%)

X + Y%

X - Y%

About Percentage Calculator

Percentage calculations underlie everyday financial decisions — from computing GST on invoices to evaluating exam performance and comparing price discounts. Most online calculators handle only one formula at a time, requiring multiple page loads for related computations. Having all four core percentage modes simultaneously visible removes that friction and lets you cross-check results between modes instantly.

How It Works

Each of the four calculation cards implements a distinct formula. "What is X% of Y" computes Y × (X/100). "X is what % of Y" computes (X ÷ Y) × 100. "Percentage change" computes ((New − Old) ÷ |Old|) × 100, with sign indicating direction. "Add/subtract percentage" computes Value × (1 ± Percent/100).

All four cards evaluate in real time using React state: any keystroke in an input field triggers a recalculation, and the result updates without requiring a button click. Quick-percentage buttons (5%, 10%, 18%, 25%, 50%) pre-fill the percentage input of whichever card is currently active, streamlining common use cases like GST rates or standard tip amounts.

The percentage change card uses color coding — green for positive change (increase) and red for negative change (decrease) — so the direction of change is immediately recognizable without reading the sign character.

Who Is This For

A shopkeeper computing the selling price after adding an 18% GST margin to a base cost of ₹4,250 before printing a price tag.

A student checking their aggregate percentage across five subjects with varying total marks, using the "X is what % of Y" card for each subject.

A finance analyst computing the month-over-month revenue change — comparing ₹8.4 lakh in March to ₹9.1 lakh in April — using the percentage change card.

A delivery platform calculating the tip amount on a ₹349 order at 15% to verify what a customer will be charged before they confirm the payment.

How to Use

All four calculation modes are visible at once — no tabs needed

Enter values in any card and see the result instantly

Use quick percentage buttons (5%, 10%, 18%, 25%, 50%) for common calculations

Green/red colors indicate increase or decrease in the percentage change card

Frequently Asked Questions

Use the "X is what % of Y" card. Enter your marks scored as X and total marks as Y. For example, 425 out of 500 = 85%.

Percentage change = ((New Value - Old Value) / Old Value) x 100. A positive result means increase, negative means decrease.

Use the "X + Y%" card. Enter the base price as X and GST rate (5%, 12%, 18%, or 28%) as Y to get the final price including GST.

Use the "X is what % of Y" card. For example, to find what percentage 250 is of 1000, enter X=250 and Y=1000 to get 25%.

Use the percentage change card with the original price as the Old Value and the sale price as the New Value. A negative result is the discount percentage. For example, an item originally priced at ₹800 selling for ₹600 shows -25%, meaning a 25% discount.

Use the "X + Y% = ?" card with the final amount as X and enter the percentage as a negative number. Alternatively, divide the final amount by (1 + percentage/100). For example, if a price after an 18% GST increase is ₹1,180, the original was ₹1,180 ÷ 1.18 = ₹1,000.

Percentage = (Target / Total) × 100. If you scored 68 out of 80 in an exam, the percentage is (68 ÷ 80) × 100 = 85%. This calculation is handled by the "X is what % of Y" card automatically.