How do you calculate percentage increase or decrease?

Subtract the old value from the new value, divide by the absolute value of the old value, and multiply by 100. DocTool calculates this automatically and shows the step-by-step math.

Can I use this for shopping sale discount calculations?

Yes! Simply enter the original price and discount percentage to instantly find the final discounted price and exact money saved.

Is this percentage calculator mobile-friendly?

Yes, it is fully optimized with big touch buttons and responsive layout for quick calculations on smartphones and tablets.

Percentage Calculator

Fast, multi-mode calculator for percentage values, percentage changes, discounts, and ratio conversions.

Calculation 1Portion of Value

What is X% of Y?

Percentage (%)

Total Value (Y)

Answer:

(18 ÷ 100) × 500 = 90

Calculation 2Ratio to Percent

X is what percent of Y?

Part (X)

Whole (Y)

Answer:

25%

(45 ÷ 180) × 100 = 25%

Calculation 3Percentage Change

Percentage Change (Increase/Decrease)

Initial Value

Final Value

Change:

+35%

(Increase of 35)

((135 - 100) ÷ |100|) × 100 = 35%

Calculation 4Shopping & Tax

Discount & Final Price

Price

Discount %

Tax % (Opt.)

Final Price:

1200

You Save:

300

How To Use Percentage Calculator Online For Free

Calculate percentage portions, percentage increase or decrease, discounts, and ratio conversions instantly. Processed 100% locally and privately in your browser with zero server uploads and zero ads.

1. Select Calculation Mode

Choose What is X% of Y, Percentage Increase/Decrease, or Discount Calculation.

2. Input Values

Enter the numbers into the corresponding fields.

3. Get Instant Result & Formula

View the exact numerical answer along with the mathematical explanation step-by-step.

Why Choose DocTool Percentage Calculator?

Built for speed, client-side privacy, and flawless document output with zero ads and zero watermarks.

100% Client-Side Private

Files process directly in your browser using WebAssembly. Your documents never touch external servers or cloud databases.

Zero Watermark Added

Export clean, professional, publication-ready files without any stamps, logos, or forced branding.

Instant Processing with Zero Queue

Instant optimization and editing with zero queue times, zero server latency, and batch processing support.

100% Free Forever with Zero Popups

No account registration, no credit card, and zero intrusive ads. Enjoy uninterrupted productivity on any device.

Frequently Asked Questions

Everything you need to know about using Percentage Calculator on DocTool.