Percentage Calculator — Free Online Percent Solver

What is a percentage calculator?

A percentage calculator is a fast way to compute percent-based questions without manual formulas. This tool handles “percent of a number,” “what percent,” “increase/decrease by percent,” “percentage change,” “reverse percentage,” and conversions between fractions and percentages. It’s designed for universal use, with plain numbers and no location‑specific settings.

Who benefits from this tool?

• Students: homework checks in math, science, and economics.
• Professionals: growth rates, discounts, margins, and KPIs.
• Everyday use: sales discounts, tips, and quick comparisons.

Core percentage formulas used

• Percent of: result = (p ÷ 100) × base
• What percent: percent = (part ÷ whole) × 100
• Increase by %: new = base × (1 + p/100)
• Decrease by %: new = base × (1 − p/100)
• Percent change: change% = ((new − old) ÷ old) × 100
• Reverse percent: original = final ÷ (1 ± p/100)

Tips for accurate results

• Units: Enter plain numbers. If you track currency or units, keep them consistent across inputs.
• Percent vs decimal: 15% ≠ 0.15 unless you convert. Input percentages as whole percents (e.g., 15, not 0.15).
• Rounding: Percent calculations can produce long decimals; use sensible rounding when communicating results.
• Reverse checks: After reverse % results, verify by applying the rate forward to confirm the match.

How to use and embed this percentage calculator

Step-by-step guide

1. Choose a tab: Select the calculation type (e.g., Percent of, What percent, Increase by %).
2. Enter values: Type numbers only; the tool adapts to any context worldwide.
3. Calculate: Click Calculate to see instant results with the applied formula.
4. Reset: Use Reset to clear inputs and outputs before a new calculation.
5. Embed: Copy this single HTML file into your site or load it in an iframe for quick integration.
6. Customize: Keep the theme colors (background #F8F4EB, text #333333, content #FFFFFF) for a clean, modern look.

Frequently asked questions

HOW TO calculate a percentage of a number?

Enter the percent and the base number in the Percent of tab, then click Calculate. The tool multiplies the base by the percent divided by 100.

HOW TO find what percent one number is of another?

Open What percent, enter the part (A) and the whole (B), then Calculate. The tool computes (A ÷ B) × 100.

HOW TO add or remove a percentage?

Use Increase by % to add or Decrease by % to subtract. Enter the rate and the original value, then Calculate.

HOW TO work out percentage change?

Go to % change, enter the old and new values, and Calculate. Positive results indicate an increase; negative results a decrease.

HOW TO reverse a percentage to find the original?

Use Reverse %. Choose Increase or Decrease, enter the final value and the percent rate. The calculator divides the final by (1 ± rate/100) to reveal the original.

HOW TO convert between fractions and percentages?

Use Fraction → % for a/b × 100. Use % → Fraction to simplify p/100 into a reduced fraction.