Percentage Calculator

Quickly calculate percentages, percentage changes, discounts, and more with six essential tools in one.

Calculations are instant · All calculations are processed in your browser

A is what % of B?

is of — %

B% of A is what?

of % = —

Percentage change (A to B)

to = — %

Add · Subtract B% from A

by % = —

Discount calculation

Original Price KRW · % off

—Payment Amount (KRW)

—Discount Amount (KRW)

VAT Calculation (10%)

KRW

—Supply Value (KRW)

—VAT (KRW)

—Total Amount (KRW)

💡 VAT is calculated at 10% based on general tax principles in Korea. If you select Amount including VAT, the input amount is divided by 1.1 to reverse-calculate the supply value and VAT. If you select Amount excluding VAT, 10% is added to the input amount. Amounts are displayed rounded to the nearest Korean Won, so please confirm your client's rounding policy when issuing tax invoices.

What is the Percentage Calculator?

Handle all your daily percentage calculations with this single, versatile tool. From simple ratios like 'A is what % of B?' to tracking stock returns or sales growth with the percentage change calculator, it's all here. Shopping? Instantly find the final price with the discount calculator. Need to handle business finances? The VAT calculator is set up for a 10% rate. Just type your numbers into any of the six modules and get instant answers. All calculations run in your browser, so your financial data is never sent to our servers.

How to use

Find the calculator you need among the six modules, such as `A is what % of B?` or `Discount calculation`.
Enter your numbers into the fields. The result is calculated and displayed in real-time as you type.
For `Add · Subtract B% from A` or `VAT Calculation (10%)`, click the toggle buttons (e.g., `＋ Add` / `－ Subtract`) to switch modes.
Click the `Example` button to automatically fill all fields with sample values and see how each calculator works.
Press the `Copy` button next to any result to copy the calculated value to your clipboard.
To start over, click the `Clear` button to reset all input fields at once.

Frequently asked questions

How is the percentage change calculated?

It uses the formula: ((New Value - Original Value) / Original Value) × 100. The result is prefixed with a `+` for an increase and is negative for a decrease, showing the direction of the change.

Is my financial data saved on your server?

No. All calculations run exclusively in your browser. None of the numbers or financial data you enter are ever sent to our servers, ensuring your information remains completely private.

How does the VAT calculator work?

It uses a 10% rate. Choosing `Amount including VAT` divides your input by 1.1 to find the base price. `Amount excluding VAT` adds 10% to your input to get the final total.

Can the payment amount be negative in the discount calculator?

Yes, if the discount rate is over 100%, the final payment will be negative. The tool will display a warning message in this case, prompting you to double-check the entered rate.