Percentage calculator FAQ

All FAQ topics

• #01 · Basics

  What is a percentage calculator?

  Learn what an online percentage calculator does, how it differs from a spreadsheet, and how to use basic, increase and decrease modes for shopping, finance and school.

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• #02 · Increase

  How to calculate percentage increase

  Learn the percentage increase formula with worked examples for salaries, rent, population growth and prices. Avoid common mistakes and verify with the increase calculator.

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• #03 · Decrease

  How to calculate percentage decrease

  Master the percentage decrease formula for discounts, budget reductions and price drops. Worked examples plus links to percent-off and discount FAQs.

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• #04 · Basics

  How to find the percentage of a number

  Find X% of Y with a simple multiply-divide trick, mental shortcuts for 10% and 25%, and calculator tips for tips, taxes and homework.

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• #05 · Shopping

  How to calculate percent off

  Learn how percent-off sales work: find discount dollars, final price and stacked offers. Shopping examples plus links to discount and sales tax FAQs.

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• #06 · Change

  How to calculate percentage change

  Find percentage change between an old value and a new value with a simple fraction formula. Compare increases, decreases and “relative change” wording for finance and school.

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• #07 · Education

  How to convert a ratio to a percentage

  Turn any part-to-part or part-to-whole ratio into a percent: divide, multiply by 100, and interpret pitfalls like “2 out of 5” vs “2 to 5”. Sports, exams and recipes included.

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• #08 · Education

  How to calculate exam score percentages

  Convert raw marks to percentages, understand weighted sections and avoid mixing up points vs percents. Study examples plus links to grade and ratio FAQs.

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• #09 · Finance

  How to calculate tax percentages

  Estimate tax as a percent of a subtotal, inclusive vs exclusive pricing and rounding on receipts. Educational only—verify rules with official sources.

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• #10 · Everyday

  How to calculate tip percentages

  Pick a tip rate, apply it pretax or post-tax according to local norms, split bills fairly and sanity-check with mental 10% anchors. Calculator examples included.

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• #11 · Basics

  What is the percentage formula?

  See the three essential percentage formulas: percent of a number, increase, decrease and change. Quick table plus links to deep-dive FAQs for each pattern.

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• #12 · Finance

  How to calculate profit margin percentage

  Learn gross and net margin formulas: profit divided by revenue, expressed as a percent. Examples, pitfalls vs markup and a reminder to verify accounting rules.

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• #13 · Shopping

  How to calculate discount percentages

  Model percent discounts, stacked promotions and psychology pricing. Compare with percent-off wording and verify checkout totals with the calculator.

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• #14 · Change

  How to calculate percentage difference

  Compare two values symmetrically with percentage difference (average baseline). Contrast with directional percentage change and avoid baseline confusion.

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• #15 · Finance

  How to calculate interest percentages

  Build intuition for simple interest as a percent of principal, APR snapshots and why compounding needs more than one percent step. Educational—not lending advice.

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• #16 · Finance

  How to calculate markup percentage

  Markup percent compares profit (or selling price minus cost) to cost. Contrast with margin, see pricing examples and avoid denominator confusion.

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• #17 · Finance

  How to calculate commission percentages

  Compute commission dollars from a percent of sales, tiered plans and net-vs-gross bases. Examples for sales reps plus links to margin and tip FAQs.

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• #18 · Education

  How to calculate grade percentages

  Combine homework, quizzes and exams with weights; run what-if scenarios for your final. Links to exam scores, ratios and the student guide.

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• #19 · Shopping

  How to calculate sales tax

  Compute sales tax on a subtotal, extract pretax amounts from tax-included totals and understand rounding. Educational only—confirm rates with official sources.

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• #20 · Basics

  Why are percentages important?

  Percentages standardise comparisons, power discounts and finance, support scientific literacy and make headlines honest when used carefully.

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