- Choose one of the three modes, depending on what you are solving for:
- What is X% of Y? — find a percentage of a total.
- X is what percent of Y? — find the percentage one value represents of another.
- Y is X% of what number? — find the total when you know an amount and its percentage.
- Enter the values shown and the tool returns the result instantly.
All calculations run locally in your browser — no numbers are uploaded, so you can work with personal budgets, grades and business figures privately.
The three modes cover the most common percentage questions people meet daily: applying a percentage, comparing a part to a whole, and reversing a percentage to find a base amount.
Tips
Pick the mode that matches the question you are answering. For a discount, “What is X% of Y?” tells you the amount off. For a grade, “X is what percent of Y?” shows the fraction as a percentage. For growth or reverse calculations, the third mode recovers the original total.
Double-check which number is the total versus the part — swapping them is the most common mistake. When you see the result, quickly estimate whether it makes sense; a percentage should never move in the wrong direction from your input.
Why use it
Percentages appear everywhere — taxes, tips, discounts, grades, savings interest and growth rates. Working them out by hand is error-prone, and rounding in the wrong place changes the answer. This calculator is instant, free and private, running entirely in your browser with no install and no upload.
Real-world use cases
- Home buying: Estimate monthly payment and total interest before talking to a bank. Adjust years vs. rate to see the trade-off.
- Budgeting: Use percentage and discount calculators to quickly check sale prices while shopping.
- Planning: Workday and unit converters save time when coordinating across teams and regions.
How accurate is it?
Results use standard formulas with double-precision floats, matching Excel and banking calculators to within cents. Assumptions are shown in the note (e.g., monthly compounding). For legally binding totals, confirm with the provider because fees, insurance and rounding rules differ.
Pro tips
- For loans, compare equal-payment vs equal-principal: the latter starts higher but pays less interest overall.
- For fuel and discount math, keep one decimal extra while comparing options, then round for display.
- Save results with a screenshot or copy; everything is local so refreshing clears the form.