What is a Percentage Formula?
Updated on 22.06.2026
A percentage formula is used to calculate the percentage of numbers. It is one of the most important formulas in arithmetic because we start using percentages from our school days and continue using them throughout our lives.
Whether it is calculating marks, discounts, profit and loss, interest, or comparing values, percentages are used almost everywhere.
Percentage formulas are also very important for competitive exams such as SSC, RRB, Banking, Defence, and other government examinations, where percentage-based questions are frequently asked.
The concept is easy to understand, simple to remember, and quick to apply, making it an essential topic for both academics and competitive exam preparation.
Percentage Formula: Basic
% = (Part/Total) × 100
Where:
Part = The value whose percentage is to be found.
Total = The whole or total value.
Example: 1
A house has 3 rooms, out of which 2 rooms are occupied. Find the percentage of rooms that are not occupied.
Step 1: Find the number of unoccupied rooms.
Unoccupied Rooms = Total Rooms- Occupied Rooms
=3 − 2 = 1
Step 2: Apply the percentage formula.
Percentage of Unoccupied Rooms = (1 / 3) × 100
= 33.33%
Answer: 33.33% of the rooms are not occupied.
Example 2
A Class 12 section has 100 students. Out of them, 35 are girls. What percentage of students are girls?
Total Students = 100
No of Girls = 35 (Part)
Using the percentage formula:
(Part/total)x100
% Girls = (No of Girls/Total Students)x100
= (35/100) × 100
= 35%
Answer: 35% of the students in the class are girls.
Example 3
Ramesh scored 72 marks in Mathematics. If the total marks in Mathematics was 81, calculate the percentage of marks scored by Ramesh.
Total Marks = 81
Marks Scored by Ramesh = 72 (Part)
Using the percentage formula:
% Marks Scored = (Marks Scored/Total Marks)x100
= (72/81) × 100
= 88.89%
Answer: Ramesh scored 88.89% marks in Mathematics.
Formula to Find Value from Percentage
When the percentage and the total value are given, this formula is used:
Value = (Percentage/100) × Total Value
Example
Find 25% of 500.
Value = (25/100) × 500
= 500/4
= 125
Answer: 25% of 500 is 125.
Shortcut for SSC/RRB aspirants=25% = 1/4, so 25% of 500 = 500 ÷ 4 = 125. Fast.
Example 2: Find 33% of 600
Value= (33/100)x600
=198
Answer: 33% of 600 is 198.
Formula to Find Total Value from Percentage
Total Value = (Value × 100) / Percentage
Example 1
If 20% of a number is 140, find the number.
Here,
Value = 140
Percentage = 20
Using the formula:
Total Value = (Value × 100) / Percentage
= (140 × 100) / 20
= 700
Answer: The number is 700.
Example 2: If 12.5% of a number is 280, find the number.
If 12.5% of a number is 280, find the number.
Here,
Value = 280
Percentage = 12.5
Using the formula:
Total Value = (Value × 100) / Percentage
= (280 × 100) / 12.5
= 2240
Answer: The number is 2240.
Percentage Increase Formula
Formula:
Percentage Increase = (Price Increase / Original Price) × 100
= ((New Price − Original Price) / Original Price) × 100. For more practice, check our percentage increase section.
Example: 1
A shopkeeper was selling a book for ₹250 a few days ago, but today he is selling the same book for ₹350. Calculate the percentage increase in the price of the book.
Original Price = ₹250
New Price = ₹350
Price Increase = New Price − Original Price
= ₹350 − ₹250
= ₹100
Using the percentage increase formula:
% Increase = (100 / 250) × 100
= 40%
Answer: The price of the book increased by 40%.
Example 2
A Class 12 section of a school had 35 students in July 2025. In August 2025, the section had 41 students. Calculate the percentage increase in the number of students.
Number of Students in July 2025 = 35 (Original Number of Students)
Number of Students in August 2025 = 41
Increase in the Number of Students = 41 − 35
= 6
Using the percentage increase formula:
% Increase = ((Number of Students in August 2025 − Number of Students in July 2025) / Number of Students in July 2025) × 100
= ((41 − 35) / 35) × 100
= 17.14%
Answer: The number of students increased by 17.14%.
Percentage Decrease Formula
Formula:
Percentage Decrease = ((Original Value − New Value) / Original Value) × 100
Example 1:
In 2025, the price of a book was ₹350. In 2026, the price of the book decreased to ₹250. Calculate the percentage decrease in the price of the book.
Original Price = ₹350 (Price of the book before the reduction)
New Price = ₹250 (Price of the book after the reduction)
Price Decrease = Original Price − New Price
= ₹350 − ₹250
= ₹100
Using the percentage decrease formula:
% Decrease = (100 / 350) × 100
= 28.57%
Answer: The price of the book decreased by 28.57%.
Example 2
In the RRB examination, the total vacancies for Assistant Section Officer (ASO) were 435 in 2024. However, in the 2025 notification, the total vacancies for ASO reduced to 350. Calculate the percentage decrease in vacancies.
Vacancies in 2024 = 435 (Original Value)
Vacancies in 2025 = 350 (New Value)
Decrease in Vacancies = 435 − 350
= 85
Using the percentage decrease formula:
Percentage Decrease = (85 / 435) × 100
= 19.54%
Answer: The vacancies decreased by 19.54%. For more practice on percentage decrease, check our percentage decrease section.
Successive Percentage Change Formula
When a value is increased or decreased more than once, the overall percentage change is called a Successive Percentage Change.
Formula
Net Percentage Change = a + b + (ab/100)
Where a is first change in percentage and b is successive change in the percentage.
Use a positive sign (+) for an increase and a negative sign (−) for a decrease.
Example: 1
In 2024, an SSC examination had a total of 4,350 vacancies across all categories. In a corrigendum, the total vacancies were increased by 10%.
However, in the next corrigendum, the total vacancies were decreased by 4%. Calculate the overall percentage change in vacancies.
Original Vacancies = 4,350
Step 1: Calculate the increase of 10%
10% of 4,350 = (10/100) × 4,350
= 435
Total Vacancies after 10% Increase
= 4,350 + 435
= 4,785
Step 2: Calculate the decrease of 4%
4% of 4,785 = (4/100) × 4,785
= 191.4
Total Vacancies after 4% Decrease
= 4,785 − 191.4
= 4,593.6
Step 3: Find the overall increase
Total Increase = 4,593.6 − 4,350
= 243.6
Percentage Increase = (243.6 / 4,350) × 100
= 5.6%
Answer: The total vacancies increased by 5.6%.
Shortcut Method for SSC, RRB, Bank, and Other Competitive Exams
Net Percentage Change
= 10 + (-4) + (10 × -4)/100
= 10 − 4 − 0.4
= 5.6%
Answer: The net increase in vacancies is 5.6%.
Percentage Formula Sheet PDF
The following table summarizes the most important percentage formulas covered in this article.
| Formula | Expression |
| Basic Percentage | (Part / Total) × 100 |
| Value from Percentage | (Percentage / 100) × Total Value |
| Total Value from Percentage | (Value × 100) / Percentage |
| Percentage Increase | ((New Value − Original Value) / Original Value) × 100 |
| Percentage Decrease | ((Original Value − New Value) / Original Value) × 100 |
| Successive Percentage Change | a + b + (ab / 100) here a = First percentage change b = Second percentage change |
Download the percentage formula sheet:
Conclusion:
Percentage formulas are among the most important formulas in arithmetic and are widely used in school mathematics, daily life, and competitive examinations such as SSC, RRB, Banking, Defence, and other government exams.
By understanding the basic percentage formula, formulas to find values and totals, percentage increase, percentage decrease, and successive percentage change, students can solve a wide variety of percentage-based questions quickly and accurately.
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