Percentage Calculator — How to Calculate Percentage of Marks, Discounts & GST in India

Percentage is one of the most frequently used mathematical concepts in daily life in India — from calculating your exam marks and salary hike to figuring out GST on purchases and discounts during Diwali sales. Despite being taught in school, many people struggle with percentage calculations when they need them in real situations. This guide covers every common percentage scenario with simple formulas and practical Indian examples.

The Basic Percentage Formula

The fundamental formula to calculate percentage is:

Percentage = (Value / Total Value) x 100

For example, if you scored 420 marks out of 500, your percentage is (420/500) x 100 = 84%.

Use the Percentage Calculator to instantly compute any percentage calculation without manual math.

How to Calculate Percentage of Marks

This is the most common percentage calculation for Indian students, especially during board exam results.

Formula: Marks Percentage

Percentage = (Total Marks Obtained / Maximum Marks) x 100

Example: CBSE Class 12 Results

Anika scored the following marks in her CBSE Class 12 exams:

• English: 88/100
• Mathematics: 95/100
• Physics: 78/100
• Chemistry: 82/100
• Computer Science: 91/100

Total marks obtained = 88 + 95 + 78 + 82 + 91 = 434

Maximum marks = 500

Percentage = (434/500) x 100 = 86.8%

CGPA to Percentage Conversion

Many universities in India use CGPA (Cumulative Grade Point Average) instead of percentage. The common conversion formulas are:

• CBSE (Class 10): Percentage = CGPA x 9.5 (e.g., CGPA 8.6 = 81.7%)
• Mumbai University: Percentage = (CGPA - 0.75) x 10 (e.g., CGPA 7.5 = 67.5%)
• VTU: Percentage = (CGPA - 0.75) x 10
• Anna University: Percentage = CGPA x 10 (approximate)

For accurate conversions specific to your university, use the CGPA to Percentage Converter.

How to Calculate GST Percentage

Understanding GST calculation is essential for every Indian consumer and business owner.

Calculating GST on a Product

GST Amount = (Original Price x GST Rate) / 100

Final Price = Original Price + GST Amount

Example: GST on Electronics

You are buying a smartphone priced at Rs 25,000 (before GST). The GST rate on smartphones is 18%.

• GST Amount = (25,000 x 18) / 100 = Rs 4,500
• CGST (Central GST) = Rs 2,250 (9%)
• SGST (State GST) = Rs 2,250 (9%)
• Final Price = Rs 25,000 + Rs 4,500 = Rs 29,500

Reverse GST Calculation (Finding Original Price)

If you know the GST-inclusive price and want to find the original price:

Original Price = GST-Inclusive Price / (1 + GST Rate/100)

Example: A bill shows Rs 11,800 inclusive of 18% GST. Original price = 11,800 / 1.18 = Rs 10,000.

Use the GST Calculator for instant GST calculations with proper CGST/SGST/IGST breakup.

How to Calculate Discount Percentage

During Flipkart Big Billion Days, Amazon Great Indian Festival, or Diwali sales, knowing how to verify discounts helps you spot real deals.

Formula: Discount Percentage

Discount % = ((MRP - Selling Price) / MRP) x 100

Example: Clothing Sale

A branded shirt has MRP Rs 2,499 and is selling for Rs 1,499.

• Discount Amount = Rs 2,499 - Rs 1,499 = Rs 1,000
• Discount % = (1,000 / 2,499) x 100 = 40.01%

Double Discount / Successive Discounts

Sometimes shops offer "50% + 20% off." This does NOT mean 70% off. Here is how to calculate:

• MRP = Rs 5,000
• First discount (50%): Rs 5,000 - Rs 2,500 = Rs 2,500
• Second discount (20% on reduced price): Rs 2,500 - Rs 500 = Rs 2,000
• Effective discount = (5,000 - 2,000) / 5,000 x 100 = 60% (not 70%!)

How to Calculate Salary Hike Percentage

During appraisal season, every Indian employee wants to know their hike percentage.

Formula: Hike Percentage

Hike % = ((New Salary - Old Salary) / Old Salary) x 100

Example

Vikram's CTC was Rs 8,00,000 per annum. After appraisal, it became Rs 9,20,000.

• Increase = Rs 9,20,000 - Rs 8,00,000 = Rs 1,20,000
• Hike % = (1,20,000 / 8,00,000) x 100 = 15%

The average salary hike in India for 2026 is projected at 9.5-10.2% across industries. IT sector averages 10-12%, while manufacturing averages 8-9%.

Percentage Increase and Decrease Formulas

Percentage Increase

% Increase = ((New Value - Original Value) / Original Value) x 100

Example: Petrol price increased from Rs 103 to Rs 108. Increase = ((108-103)/103) x 100 = 4.85%

Percentage Decrease

% Decrease = ((Original Value - New Value) / Original Value) x 100

Example: A stock fell from Rs 1,500 to Rs 1,275. Decrease = ((1500-1275)/1500) x 100 = 15%

Quick Reference: Common GST Rates in India

• 0% GST: Fresh fruits, vegetables, milk, eggs, curd, bread
• 5% GST: Packaged food items, sugar, tea, edible oil, footwear below Rs 1,000
• 12% GST: Butter, ghee, mobile phones, apparel above Rs 1,000
• 18% GST: Electronics, restaurants (non-AC), IT services, financial services
• 28% GST: Cars, luxury items, aerated drinks, tobacco, cement

Calculate the exact GST for your specific product or service using the GST Calculator.

Frequently Asked Questions

Q: How do I calculate what percentage one number is of another?

Use the formula: (Part / Whole) x 100. For example, if you spent Rs 15,000 on rent out of a Rs 50,000 salary, rent is (15,000/50,000) x 100 = 30% of your salary. The Percentage Calculator handles all such calculations instantly.

Q: How to find the original price before a discount?

Use: Original Price = Sale Price / (1 - Discount%/100). If an item costs Rs 750 after a 25% discount, original price = 750 / (1 - 0.25) = 750 / 0.75 = Rs 1,000.

Q: What is the percentage formula for competitive exams?

For SSC, Banking, and other competitive exams, the key percentage formulas are: (1) Basic: (Part/Whole) x 100, (2) Successive: a + b + ab/100 for two successive changes a% and b%, (3) Fraction shortcuts: 1/2 = 50%, 1/3 = 33.33%, 1/4 = 25%, 1/5 = 20%, 1/8 = 12.5%. Memorizing these fractions speeds up calculations significantly.

Q: How to calculate percentage in Excel?

In Excel or Google Sheets, use the formula =A1/B1 and format the cell as Percentage. For example, if A1 contains marks obtained (85) and B1 contains total marks (100), the formula =A1/B1 with percentage formatting will show 85%.