Fraction Calculator with Steps
Fractions & Mixed Numbers
Whole-number fields are optional. Step-by-step working expands after solving.
Step-by-step arithmetic
Follow each mathematical step to lowest terms.
Add, subtract, multiply and divide fractions and mixed numbers
Use this free fraction calculator to add, subtract, multiply and divide proper, improper, and mixed fractions, with working shown step by step and results simplified to lowest terms.
Every calculation evaluates exact rational arithmetic with automatic reduction to lowest terms (simplest form). Supporting proper fractions, improper (top-heavy) fractions, and mixed numbers—including negative mixed numbers and large BigInt integers—all computations run 100% locally in your browser with zero data transmission.
Understanding Fraction Anatomy
A fraction represents a proportional division ratio between two integers, written as a / b where the denominator cannot be zero (b ≠ 0):
Fraction Structure
Numerator (top): Counts how many equal fractional parts are taken.
Denominator (bottom): The total number of equal parts dividing the whole unit.
Value < 1
The numerator is strictly smaller than the denominator (e.g. 3/5, 2/7).
3/5 = 0.6Value ≥ 1
Improper (top-heavy): numerator ≥ denominator (9/4). Mixed number: whole integer + fraction (2 ¼).
9/4 = 2 ¼ = 2.25Core Rules of Fraction Arithmetic
Fractions follow four exact algebraic algorithms depending on the selected arithmetic operator:
Adding & Subtracting Fractions
Find the Least Common Denominator (LCD), scale each fraction to equal part sizes, and combine numerators:
a/b ± c/d = (a·d ± c·b) / (b·d)Multiplying Fractions
No common denominator is needed: multiply numerators straight across and denominators straight across:
(a/b) × (c/d) = (a × c) / (b × d)Dividing Fractions (Keep-Change-Flip)
Multiply the first fraction by the reciprocal (inverse) of the second fraction:
(a/b) ÷ (c/d) = (a × d) / (b × c)Simplifying to Lowest Terms (Simplest Form)
Divide numerator and denominator by their Greatest Common Factor (GCF in US math, HCF in UK maths):
(a ÷ gcd) / (b ÷ gcd)Mixed Number Calculator: Adding, Subtracting, Multiplying, and Dividing Mixed Numbers
To calculate with mixed numbers, always convert each mixed number into an improper (top-heavy) fraction first: multiply the whole integer by the denominator, add the numerator, and place the result over the denominator. Here are checked worked examples for all four operations:
Adding Mixed Numbers
Convert to improper fractions, find common denominator (4), and add:
2 ½ + 1 ¾ = 5/2 + 7/4 = 10/4 + 7/4 = 17/4 = 4 ¼Subtracting Mixed Numbers
Convert to improper fractions, express over LCD (6), and subtract:
3 ⅓ − 1 ½ = 10/3 − 3/2 = 20/6 − 9/6 = 11/6 = 1 ⅚Multiplying Mixed Numbers
Convert to improper fractions and multiply straight across:
1 ½ × 2 ⅔ = 3/2 × 8/3 = 24/6 = 4Dividing Mixed Numbers
Convert to improper fractions and multiply by the reciprocal:
2 ¼ ÷ ¾ = 9/4 ÷ 3/4 = 9/4 × 4/3 = 36/12 = 3How to Convert Improper (Top-Heavy) Fractions to Mixed Numbers
To convert an improper fraction to a mixed number, divide the numerator by the denominator. The whole quotient is the integer part, and the remainder becomes the new numerator over the original denominator:
Example: Convert 29/6 to a mixed number
Divide 29 ÷ 6 = 4 with a remainder of 5. Placing remainder 5 over original denominator 6 yields 4 ⅚.
Reverse: Convert 4 ⅚ back to an improper fraction
Multiply the whole integer by the denominator and add the numerator: (4 × 6 + 5) / 6 = 29/6.
How to Work Out a Fraction of an Amount (Fraction of a Number)
To find a fraction of an amount or number, follow this two-step formula: Divide the total amount by the denominator, then multiply by the numerator ((Amount ÷ Denominator) × Numerator):
Fraction of an Amount (£)
Find 3/5 of £40:
1. Divide by denominator: £40 ÷ 5 = £8
2. Multiply by numerator: £8 × 3 = £24
3/5 of £40 = £24Fraction of a Number ($)
Find 3/4 of $20:
1. Divide by denominator: $20 ÷ 4 = $5
2. Multiply by numerator: $5 × 3 = $15
3/4 of $20 = $15Tip: In our calculator, you can calculate a fraction of an amount directly. Enter the whole number amount in the first Whole field (leaving numerator and denominator empty), select the multiplication operator (×), and enter the fraction in the second field.
Common Mistake: Why You Cannot Just Add Denominators
Why 1/2 + 1/3 ≠ 2/5
A frequent error in GCSE, KS3, and middle school maths is adding numerators and denominators straight across: (1 + 1) / (2 + 3) = 2/5 = 0.4. But 1/2 alone is already 0.5, so the combined total cannot possibly be smaller than one of its parts!
Fractions can only be combined when their slices represent equal unit sizes. Always find a common denominator (the Least Common Denominator of 2 and 3 is 6): 3/6 + 2/6 = 5/6 (≈ 0.8333).
Quick Reference Tables: Common LCDs and Conversions
Least Common Denominators (LCD)
| Denominators | LCD | Shared Multiples |
|---|---|---|
| 2 and 3 | 6 |
6, 12, 18, 24... |
| 4 and 6 | 12 |
12, 24, 36, 48... |
| 3 and 5 | 15 |
15, 30, 45, 60... |
| 7 and 8 | 56 |
56, 112, 168... |
The LCD is the lowest common multiple (LCM) of the denominators.
Fraction, Decimal & Percent
| Fraction | Simplest | Decimal | Percent |
|---|---|---|---|
| 1/8 | 1/8 | 0.125 |
12.5% |
| 1/5 | 1/5 | 0.2 |
20% |
| 1/4 | 1/4 | 0.25 |
25% |
| 1/3 | 1/3 | 0.3333… |
33.33% |
| 1/2 | 1/2 | 0.5 |
50% |
| 2/3 | 2/3 | 0.6667 |
66.67% |
| 3/4 | 3/4 | 0.75 |
75% |
Need percentages or discounts? Use our percentage calculator.
Step-by-Step Worked Examples
Example 1: Adding Unlike Fractions
2/7 + 3/8-
1
Find common denominator: LCD of 7 and 8 is
56. -
2
Scale numerators:
(2 × 8)/56 = 16/56and(3 × 7)/56 = 21/56. -
3
Add numerators:
16 + 21 = 37→37/56. -
4
Lowest terms: 37 and 56 share no common factors. Final: 37/56.
Example 2: Multiplying Mixed Numbers
1 ½ × 2 ⅔-
1
Convert to improper:
1 ½ = 3/2and2 ⅔ = 8/3. -
2
Multiply across:
(3 × 8) / (2 × 3) = 24 / 6. -
3
Reduce by GCF/HCF: Divide 24 and 6 by 6:
24 ÷ 6 = 4. -
4
Final value: Whole number integer 4.
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Frequently Asked Questions FAQs
What is 1/2 + 1/3?
1/2 + 1/3 = 5/6. Because the denominators (2 and 3) are different, first find their least common denominator (LCD), which is 6. Convert each fraction to an equivalent form (3/6 + 2/6) and add the numerators: 3 + 2 = 5, giving 5/6 in simplest form.
What is 3/4 - 1/3?
3/4 − 1/3 = 5/12. Find the lowest common denominator of 4 and 3, which is 12. Convert each fraction: 3/4 = 9/12 and 1/3 = 4/12. Subtracting the numerators yields (9 − 4)/12 = 5/12.
What is 3/4 ÷ 1/2?
3/4 ÷ 1/2 = 3/2 (or 1 ½ as a mixed number). Using Keep-Change-Flip (multiplying by the reciprocal), change the division into multiplication: 3/4 × 2/1 = 6/4. Dividing numerator and denominator by 2 simplifies the result to 3/2 = 1 ½ = 1.5.
How do you add mixed numbers?
To add mixed numbers like 2 ½ + 1 ¾, first convert each to an improper (top-heavy) fraction: 2 ½ = 5/2 and 1 ¾ = 7/4. Next, find a common denominator (4) to get 10/4 + 7/4 = 17/4, which simplifies to the mixed number 4 ¼.
How do you subtract mixed numbers?
To subtract mixed numbers such as 3 ⅓ − 1 ½, first convert them into improper fractions: 3 ⅓ = 10/3 and 1 ½ = 3/2. Find the common denominator (6) to express them as 20/6 − 9/6 = 11/6, which equals 1 ⅚.
How do you divide mixed numbers?
Convert both mixed numbers to improper fractions before dividing. For example, 2 ¼ ÷ ¾ becomes 9/4 ÷ 3/4. Multiplying by the reciprocal gives 9/4 × 4/3 = 36/12 = 3.
How do you convert an improper (top-heavy) fraction to a mixed number?
Divide the numerator (top number) by the denominator (bottom number). The whole quotient is the integer part, and the remainder becomes the new numerator over the original denominator. For example, 29 ÷ 6 = 4 remainder 5, so 29/6 = 4 ⅚.
How do you find a fraction of an amount (fraction of a number)?
Divide the amount by the denominator, then multiply by the numerator. For example, to find 3/5 of £40, compute £40 ÷ 5 = £8, then £8 × 3 = £24. Similarly, 3/4 of $20 is 20 ÷ 4 × 3 = $15.
How do you find the least common denominator (LCD)?
The least common denominator (LCD) is the lowest common multiple (LCM) of the denominators. List the multiples of each denominator until you identify the smallest shared number. For example, the multiples of 4 are 4, 8, 12, 16... and the multiples of 6 are 6, 12, 18... making 12 the LCD of 4 and 6.
Why can you not just add the denominators?
Fractions represent equal fractional parts of a whole. Adding 1/2 + 1/3 cannot equal 2/5 (0.4) because 1/2 alone is already 0.5. Denominators indicate part sizes; you must scale them to equal units using a common denominator (6) so that 3/6 + 2/6 = 5/6.
What is the reciprocal of a fraction?
The reciprocal of a fraction is created by swapping its numerator and denominator (flipping it). The reciprocal of 3/4 is 4/3, and the reciprocal of an integer n (n/1) is 1/n. Multiplying any non-zero fraction by its reciprocal always equals 1.
How do you compare two fractions to see which is larger?
Convert both fractions to have a shared common denominator. For example, to compare 3/5 and 2/3, express both with a denominator of 15: 3/5 = 9/15 and 2/3 = 10/15. Because 10/15 > 9/15, 2/3 is greater than 3/5.
What is the highest common factor (HCF) or GCF of a fraction?
The greatest common factor (GCF in US math) or highest common factor (HCF in UK maths) is the largest whole number that divides evenly into both numerator and denominator. For 18/24, the GCF/HCF is 6, reducing 18/24 to lowest terms: 3/4.
How do you multiply two fractions?
Multiplying fractions does not require a common denominator: multiply the numerators straight across and the denominators straight across: (a/b) × (c/d) = (a × c) / (b × d). For instance, (2/3) × (5/7) = 10/21. Once multiplied, reduce the result to simplest form.
Can a fraction have a denominator of zero?
No. Division by zero is mathematically undefined. A denominator represents how many equal pieces divide a whole; because a unit cannot be divided into zero pieces, entering zero as a denominator produces an error.
How does this calculator handle negative mixed numbers and large integers?
This calculator accurately handles negative mixed numbers (entering −2 with 3/4 treats the entire quantity as −(2 + ¾) = −11/4). It also computes using arbitrary-precision JavaScript BigInt arithmetic, ensuring 100% exact fractions without 64-bit floating-point rounding errors.
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