How do I calculate a percentage of a number?

Convert the percentage to decimal form by dividing by 100, then multiply by the number. For example, 20% of 80 = 0.2 × 80 = 16.

How do I find what percent one number is of another?

Divide the part by the whole and multiply the result by 100. For example, 15 out of 60 is (15/60) × 100 = 25%.

How do I calculate percentage increase?

Subtract the original value from the new value, divide by the original, and multiply by 100. For example, increase from 50 to 65: ((65-50)/50)×100 = 30%.

How do I calculate a discount or sale price?

Multiply the original price by the discount percentage (as a decimal) to get the discount amount. Subtract from the original price to get the sale price. For example, 20% off $80: discount = 0.2×80 = $16, sale price = $64.

Can I customize the letter grade scale?

Yes, enable the custom scale option in the Letter Grade tab. Set your own minimum percentages for A, B, C, and D, and the calculator automatically assigns the appropriate letter grade.

How do I reverse calculate a percentage (find original price before discount)?

Divide the discounted price by (1 − discount percentage as decimal). For example, if you paid $64 after a 20% discount, the original price was $64 / 0.8 = $80.

Percentage Calculator – Instant Results & Custom Letter Grade

Calculate percent of a number, increase/decrease, tip, discount, reverse percentage, and convert percentages to letter grades. Custom scale supported. All with live gauge, step‑by‑step formulas, and shareable state.

Percentage (%)

Number

Part

Whole

Original

New

Original

New

Part

Percentage (%)

✏️ Custom letter grade scale

A min %

B min %

C min %

D min %

Result--

Description--

📐 Step‑by‑step

🧮 Need to calculate your weighted grade?

Open Weighted Grade Calculator →

How to Use This Percentage Calculator

Choose a tab for the calculation you need. Values update live. Each result includes a step‑by‑step breakdown of the formula and actual numbers. The built‑in letter grade converter turns any percentage into a standard A–F grade – perfect for test scores or quick grade checks. You can also customize the letter grade scale to match your school's policy.

Letter Grade Conversion Table (Default)

Letter	Percent Range	Letter	Percent Range
A+	97–100%	C+	77–79%
A	93–96%	C	73–76%
A-	90–92%	C-	70–72%
B+	87–89%	D+	67–69%
B	83–86%	D	63–66%
B-	80–82%	D-	60–62%
		F	Below 60%

Real‑World Examples

Test Score Percentage

You got 42 out of 50 on a midterm. Tab 2 shows 84% → a B letter grade. The step‑by‑step reveals (42/50)×100 = 84%.

Discount Shopping

A $120 jacket is 35% off. Tab 1 gives discount $42, sale price $78. Formula: 35% of 120 = 0.35×120 = 42.

Salary Raise

Salary goes from $48,000 to $52,800. Tab 3 calculates a 10% increase. (52800-48000)/48000 × 100 = 10%.

Grade Planning

You scored 78% on your current work and need an 85% overall. The final exam is 30% of the grade. Combine with our Final Grade Calculator to find the required exam score.