Percentage Calculator (2026) - X% of Y & Change

Three percent questions, one toggle row

Tip math is X% of Y. Raise math is increase mode. Exam score "what percent" is the third mode. Defaults in mode 1: 20% of 250 = 50.00.

Increase/decrease adds a direction dropdown. +20% on 250 = 300. -20% on 250 = 200.

Copy writes the detail line from the secondary card.

Finance pages extend the same math

Markdown percent on a list price is the Discount & Sales Price Calculator with sale price output.

Tax on a subtotal uses rate as percent in the VAT / GST Tax Calculator.

ROI percent from dollar outcomes is the ROI Calculator when you have initial and final balances.

Sanity-check inputs before quoting

Percent without "%" sign in the field: type 20 for 20%, not 0.20.

Stacked discounts (20% then 10%) are not one 30% pass. Run twice or multiply factors (0.8 x 0.9).

Word-count trim targets pair with the Word & Character Counter after you compute the cut.

Frequently Asked Questions (FAQ)

What do the three modes do?

X% of Y: result = Y x (X/100). Default 20% of 250 = 50. Increase/decrease: new = Y x (1 +/- X/100). What percent: (X/Y) x 100 when Y is not zero.

What happens if Y is zero in "what percent"?

Division by zero is blocked. Alert fires, results show n/a, copy disabled.

Can I decrease by more than 100%?

Math allows it (negative result). Useful for modeling wipeout scenarios. No hard cap on percent input.

How is this different from the discount calculator?

Discount tool pairs list price with sale price in retail language. This page is general percent arithmetic. Use the Discount & Sales Price Calculator for shelf tags.

Percentage Calculator