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Calculateur de Pourcentage — Outil en ligne gratuit

Calcule pourcentages, augmentations, réductions et plus

Calculateur de pourcentage gratuit. Trouve X% de Y, calcule augmentations, réductions et plus. Instantané, dans ton navigateur.

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Free percentage calculator — four calculations in one

Outilolis Percentage Calculateur handles the four most common percentage questions in one place: X% of Y, X is what percentage of Y, percentage change from A to B, and adding/subtracting a percentage to a value. Live results as you type. Works on phones, tablets, and desktop.

The four percentage questions

  • X% of Y — "What is 20% of 80?" → 16 (for tips, discounts, tax)
  • X is what % of Y — "30 is what % of 150?" → 20% (for test scores, market share)
  • % Change — "From 50 to 75?" → +50% (for price changes, performance)
  • Add / Subtract % — "100 plus 15%?" → 115 (for tax, markup, discount)

How to use this tool

  1. 1

    Choose a calculation type

    Four tabs handle the four common percentage questions: X% of Y, X is what % of Y, percentage change, and after-percentage value.

  2. 2

    Enter your numbers

    Type into the two number fields. Results update live as you type — no need to click a button.

  3. 3

    Read the result

    The big number at the bottom is your answer. A plain-language sentence explains what it means.

Common real-life percentage calculations

  • Restaurant tip — Bill $80, 18% tip: 80 × 0.18 = $14.40
  • Sale discount — $120 item, 25% off: 120 × 0.75 = $90
  • Sales tax — $50 + 8% tax: 50 × 1.08 = $54
  • Test score — Got 42/50: (42/50) × 100 = 84%
  • Stock gain — Bought $100, now $143: (143-100)/100 × 100 = 43% gain
  • Salary raise — $50k + 8% raise: 50000 × 1.08 = $54,000

Frequently Asked Questions

How do I calculate X% of Y?
Multiply Y by X, then divide by 100. Example: 20% of 80 = (80 × 20) / 100 = 16. Use the first tab to do this automatically.
How do I find what percentage X is of Y?
Divide X by Y, then multiply by 100. Example: 30 is what % of 150? (30 / 150) × 100 = 20%. Use the second tab.
How do I calculate percentage change?
Subtract the old value from the new, divide by the old value, multiply by 100. Example: going from 50 to 75 is a (75-50)/50 × 100 = 50% increase. Negative results mean a decrease. Use the third tab.
How do I add X% to a value?
Multiply the value by (1 + X/100). Example: 100 plus 15% tax = 100 × 1.15 = 115. Tab four does this; negative percentages subtract.
Why does percentage math seem confusing?
People mix up "percentage of" with "percentage change". A 50% increase followed by a 50% decrease does NOT return to the original — you end up at 75% of the start. Always clarify which question you're asking.
Is this calculator accurate for financial use?
Yes, for standard percentage math. For complex finance (compound interest, tax brackets, discount stacking), use a purpose-built tool like a mortgage or tax calculator.

À retenir

  • Percentage Calculateur is a free, browser-based finance tool — calculate percentages, increases, decreases & more.
  • Non signup, no downloads, no file uploads. Outils run in your browser; the few that need an outside service say so on the page.
  • Works on desktop, tablet, and mobile. Install as a PWA for offline access.

How to Use Percentage Calculateur

  1. Open the tool: Launch Percentage Calculateur on Outilolis — no account or download needed.
  2. Enter your data: Paste text, enter values, or select a file directly in your browser.
  3. Get instant results: Everything is processed locally — results appear immediately.
  4. Copy or download: Save your output or share it. Bookmark for quick access next time.

Percentage Calculateur — Quick Facts

Prix
Gratuit — sans limites, sans filigrane, sans paywall
Confidentialité
Traité dans votre navigateur. Les outils qui ont besoin d’un service externe l’indiquent sur la page. Les visites sont comptabilisées (Google Analytics).
Plateforme
Tout navigateur moderne — desktop, tablette ou mobile
Catégorie
Finance Outils on Outilolis
Hors ligne
Works offline after first visit (Progressive Web App)
CaractéristiqueDétails
OutilPercentage Calculateur
CatégorieFinance
Inscription requiseNon
Téléversement de fichierAucun — traité dans le navigateur
Compatible mobileEntièrement adaptatif
CoûtGratuit pour toujours

Why Use Percentage Calculateur?

You should try Percentage Calculateur for a quick, private way to calculate percentages, increases, decreases & more. Processing happens in your browser and files are never uploaded; the few tools that need an outside service say so on the page.

On the other hand, dedicated APIs or desktop tools suit batch processing better. They also handle server-side automation. For everyday tasks, browser tools offer the best speed, privacy, and convenience.

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100% Confidentialité. Cet outil fonctionne entièrement dans votre navigateur. Vos données ne sont jamais envoyées à un serveur.