How the Math Works
Percentages appear everywhere — sale tags, exam scores, tip calculations, growth reports, and tax lines. The challenge is not the concept itself but picking the right formula for the question you actually have.
Vertex Solutions' Percentage Calculator covers four common scenarios in one tool. Pick a mode, enter two numbers, and the answer appears instantly. No formulas to memorize, and no data leaves your browser.
What the Calculator Shows You
The calculator offers four modes:
- X% of Y — Find a percentage of a number (e.g., 15% of 200).
- X is what % of Y — Find what proportion one number represents of another (e.g., 30 is what % of 120).
- Increase X by Y% — Add a percentage to a value (e.g., increase 500 by 10%).
- Decrease X by Y% — Subtract a percentage from a value (e.g., decrease 500 by 10%).
Each mode labels its input fields clearly, and results update as you type.
When This Calculator Helps
- Shopping and tips — Calculate 18% of a bill or find how much a 25% tip adds.
- Academic scores — Determine what percentage you scored on a test.
- Business metrics — Compute month-over-month growth or decline percentages.
- Everyday math — Solve percentage questions without reaching for a spreadsheet.
Using the Calculator
- Open the Percentage Calculator on Vertex Solutions.
- Select the mode that matches your question using the buttons at the top.
- Enter the first value in the left input field.
- Enter the second value in the right input field.
- Read the result displayed below — it updates automatically.
Worked Examples
What is 20% of 1,500? — Multiply: 1,500 × 20 ÷ 100 = 300. A Rs. 1,500 item with a 20% discount costs Rs. 1,200.
45 is what percent of 180? — Divide and multiply by 100: 45 ÷ 180 × 100 = 25%. If you scored 45 out of 180 marks, that's a quarter of the total.
150 increased by 12% is what? — Multiply: 150 × 1.12 = 168. Useful for adding sales tax or a tip to a bill.
Enter any of these pairs in the calculator above to confirm the results.
Where the Estimate Falls Short
This tool handles single-step percentage arithmetic. It does not compute compound interest, chained discounts (e.g., 20% off then an additional 10%), or weighted averages. Results are rounded to two decimal places, which may introduce tiny differences compared to manual calculations with more precision.
The calculator performs math on whatever numbers you enter — it does not judge whether those numbers are appropriate for your situation. For financial planning, tax compliance, or investment analysis, consult a qualified professional. Review our disclaimer for full terms.
Mistakes to Avoid
- Choosing the wrong mode — "What is 20% of 80?" and "20 is what % of 80?" are different questions with different answers.
- Dividing by zero — In "what percent" mode, the total (second value) must not be zero.
- Confusing decrease with final price — Decrease mode needs the original amount and the reduction percentage, not the price after the cut.
- Forgetting order matters — In "what percent" mode, the first value is the part and the second is the whole.
Getting the Most Out of It
- For a quick tip, use "X% of Y" with the bill amount as Y.
- To find a sale price, use decrease mode or switch to the Discount Calculator for a dedicated breakdown.
- For tax-inclusive or tax-exclusive pricing, the GST Calculator handles those scenarios with separate base and tax amounts.
- Double-check critical figures by running the calculation in reverse — e.g., verify that your result is indeed the stated percentage of the original.