Percentage Calculator

Percentage calculator — four tools for discounts, increases, ratios, and change

Percentage calculations come up constantly — a 20% discount on a price tag, a 15% tip on a dinner bill, a 3% revenue increase quarter over quarter, or the question "what percent of my budget did I spend?" This calculator covers the four most common percentage operations: finding a percentage of a number, finding what percent one number is of another, calculating percentage change between two values, and adding or subtracting a percentage from a number. All calculations run in the browser; nothing is uploaded.

Four calculators are arranged in a single view so you can switch between them without re‑entering data. Each calculator shows the formula used, so the tool doubles as a teaching aid for students learning percent concepts.

Who uses it

• Shoppers and consumers — calculate sale prices ("What is 30% off $85?") and compare discounts across products.
• Small‑business owners and sellers — compute margins, markups, discount amounts, and tax on invoices.
• Marketers and analysts — measure percentage change in traffic, conversions, revenue, and campaign metrics period over period.
• Students and teachers — learn and teach percentage formulas — finding a percent of a number, percent change, and percentage‑point vs. percent distinctions.

How to use it well

1. Pick the calculator that matches your question. "What is X% of Y?" for discounts and proportions; "X is what % of Y?" for ratios and scores; "% change from X to Y" for growth and decline; "X ± Y%" for markups and markdowns.
2. Enter the values and the result appears immediately — no button press needed.
3. Check the formula shown below each result to confirm you used the right calculator for your question.
4. Round only at the final step when chaining calculations — intermediate rounding can compound into a visible error.

Practical tips

• Use "% change from X to Y" to measure growth or decline — the sign (positive or negative) tells you the direction.
• Do not confuse percentage points with percent change. A rate going from 5% to 8% is a 3‑percentage‑point increase but a 60% relative increase. Know which one matters for your context.
• For discounts, use "X − Y%" (subtract) to get the final price directly rather than calculating the discount amount and subtracting separately.
• Use "X is what % of Y?" as a quick ratio tool — e.g. "$450 is what % of a $3,000 monthly budget?" = 15% spent.

Common use cases

• Calculating sale discounts and comparing final prices across products
• Computing tips, tax amounts, and service charges on bills and invoices
• Measuring revenue, traffic, or conversion‑rate changes month over month or quarter over quarter
• Splitting budgets, allocations, and expenses by percentage across categories
• Teaching and learning percentage concepts with visible formulas and instant results

Privacy and browser‑side processing

All calculations run locally in the browser. The numbers you enter — which may represent real revenue, budgets, prices, or financial data — never leave your device. For regulated financial reporting, verify results with a second method and follow your organisation's data‑handling policy.

Related searches and tools

People who use this percentage calculator often also need Tip Calculator (quickly calculate tips and split bills), APR Calculator (understand annual percentage rates on loans and credit), and Mortgage Calculator (estimate monthly payments with interest). All three run in‑browser.