Help
Requirements
Percentage Calculator requires that you have JavaScript support enabled in your browser.
Moving between fields
Mouse: Click the field.
Keyboard: Use tab key to move to the next field. Use shift+tab to move to the previous field.
Calculating
Mouse: Click the 'Calculate' button.
Keyboard: Press Enter.
The result appears in the text field at the right. If there are errors, the result field is empty, and the background of the field containing errors is red.
Decimal separator
You can use dot (.) or comma (,) as a decimal separator.
Thousands separator
Please don't use thousands separators as Percentage Calculator treats both dot and comma as a decimal separator.
Advanced Tips & Tricks
Quick Mental Calculations
- • 1%: Move decimal two places left (1% of 500 = 5)
- • 10%: Move decimal one place left (10% of 500 = 50)
- • 20%: Double the 10% result (20% of 500 = 100)
- • 15%: Add 10% + 5% (15% of 500 = 50 + 25 = 75)
- • 33.33%: Divide by 3 (33.33% of 300 = 100)
Percentage Shortcuts
- • To find 25% of any number, divide by 4
- • To find 12.5% of any number, divide by 8
- • To find 75% of any number, find 25% and multiply by 3
- • To add 10% to a number, multiply by 1.1
- • To subtract 10% from a number, multiply by 0.9
Common Business Calculations
- • Markup: If cost is $80 and selling price is $100, markup = (100-80)/80 × 100 = 25%
- • Discount: If original price is $100 and sale price is $80, discount = (100-80)/100 × 100 = 20%
- • Profit Margin: If revenue is $100 and profit is $20, margin = 20/100 × 100 = 20%
- • Tax Calculation: If tax rate is 8.5%, multiply price by 1.085 for total
Percentage Change Tricks
- • A 100% increase means doubling the original value
- • A 50% decrease means half the original value
- • Multiple percentage changes: multiply the factors (e.g., +20% then +10% = 1.2 × 1.1 = 1.32 = 32% total increase)
- • To reverse a percentage increase, divide by (1 + percentage/100)
Keyboard Shortcuts
- • Tab: Move to next field
- • Shift + Tab: Move to previous field
- • Enter: Calculate result
- • Ctrl + A: Select all text in current field
- • Escape: Clear current field
Error Prevention Tips
- • Always double-check which number is the "whole" or "base"
- • Remember: percentage OF vs percentage IS
- • Use parentheses in complex calculations
- • Round final results appropriately for your context
- • Verify results make logical sense (e.g., 150% of 100 should be 150, not 15)
Need More Help?
If you have questions or need additional support, feel free to contact us at: [email protected]