ΣCALCULATORWizard

¼ Simplify Fractions Calculator

Reduce to lowest terms, convert to mixed numbers, compare, and perform operations — all with full step-by-step solutions.

Enter numerator (top) and denominator (bottom). Negatives allowed.
Numerator
Denominator
Enter an improper fraction or a mixed number — get both forms.
Improper Fraction
― or enter mixed number ―
Whole
Fraction
Fill improper fraction or mixed number fields — last edited is used.
Which fraction is larger? Exact cross-multiplication — no rounding errors.
Fraction 1
vs
Fraction 2
Choose an operation, then enter two fractions.
Fraction 1
+
Fraction 2
📐 Step-by-Step Solution
📋 Details

What Does "Simplifying a Fraction" Mean?

A fraction is in simplest form (also called lowest terms or reduced form) when the numerator and denominator share no common factors other than 1 — their Greatest Common Divisor is 1. Simplifying a fraction means dividing both parts by their GCD until no further reduction is possible. The value of the fraction doesn't change; only its representation becomes more concise. 8/12 and 2/3 are the same quantity — the latter is simply easier to work with and recognize.

The Euclidean algorithm is the standard method for finding the GCD, running efficiently even for very large numbers. For two positive integers a and b (where a > b), the algorithm repeatedly replaces the larger with the remainder of dividing the larger by the smaller: GCD(48, 18) → GCD(18, 12) → GCD(12, 6) → GCD(6, 0) = 6. This calculator uses this exact algorithm, so results are always exact — no rounding, no approximation.

The Four Modes

Simplify

Reduces any fraction to its lowest terms. Works with negative numerators and denominators (always moves the sign to the numerator), large integers, and fractions that are already simplified (GCD = 1). Also shows the equivalent decimal, percentage, and mixed number form if the fraction is improper.

Convert: Improper Fraction ↔ Mixed Number

An improper fraction has a numerator larger than its denominator (7/4, 11/3). A mixed number combines a whole number and a proper fraction (1¾, 3⅔). To convert improper to mixed: divide numerator by denominator, the quotient is the whole part, the remainder becomes the new numerator over the original denominator. 7/4 = 1 remainder 3 = 1¾. To convert mixed to improper: multiply whole by denominator, add numerator. 1¾ = (1×4)+3 = 7/4.

Compare

Determines whether one fraction is greater than, less than, or equal to another using cross-multiplication — the only exact method that avoids floating-point errors. For a/b vs c/d: compute a×d and b×c. If a×d > b×c then a/b > c/d. This works because multiplying both sides of a/b = c/d by b×d gives the cross products. The calculator also shows both fractions converted to a common denominator to make the comparison visually intuitive.

Operate

Adds, subtracts, multiplies, or divides two fractions with full simplification. Addition and subtraction use the LCD (Least Common Denominator) method for cleaner intermediate steps. Multiplication cross-cancels before multiplying for the most efficient path. Division uses the "keep-change-flip" rule (multiply by reciprocal). Every operation shows the unsimplified intermediate result and then the simplified final answer.

Fraction Rules Quick Reference

OperationRuleExample
Adda/b + c/d = (a×d + c×b) / (b×d)1/2 + 1/3 = (3+2)/6 = 5/6
Subtracta/b − c/d = (a×d − c×b) / (b×d)3/4 − 1/2 = (6−4)/8 = 2/8 = 1/4
Multiplya/b × c/d = (a×c) / (b×d)2/3 × 3/4 = 6/12 = 1/2
Dividea/b ÷ c/d = (a×d) / (b×c)3/4 ÷ 3/8 = 24/12 = 2
Simplifya/b = (a÷GCD) / (b÷GCD)12/18 → GCD=6 → 2/3
Comparea/b vs c/d → compare a×d vs b×c2/3 vs 3/4: 8 vs 9, so 2/3 < 3/4
Improper→Mixedn/d: whole = floor(n/d), rem = n mod d7/4 = 1 remainder 3 = 1¾
Mixed→Improperw n/d = (w×d + n) / d2⅔ = (2×3+2)/3 = 8/3

Common Simplifications Reference

These are among the most frequently encountered fractions in everyday contexts. Recognizing them by sight speeds up mental math considerably.

OriginalSimplifiedDecimalPercent
2/41/20.550%
2/61/30.3333...33.3%
3/61/20.550%
2/81/40.2525%
4/81/20.550%
6/83/40.7575%
4/121/30.3333...33.3%
6/103/50.660%
10/152/30.6666...66.7%
12/163/40.7575%
15/203/40.7575%
24/362/30.6666...66.7%

Frequently Asked Questions

How do I know if a fraction is already in simplest form?
A fraction a/b is in simplest form when GCD(a, b) = 1 — the only number that divides both evenly is 1. Quick check: if both numbers are odd with no obvious shared factors, try dividing by small primes (2, 3, 5, 7). If none divide both, the fraction is likely already simplified. This calculator always confirms with the exact GCD.
Can I simplify a fraction with a negative numerator or denominator?
Yes. The convention is to keep the negative sign on the numerator, not the denominator. −8/12 = −2/3. 8/−12 also becomes −2/3 (the negative moves to the top). A fraction with negatives on both top and bottom is positive: −8/−12 = 2/3. This calculator handles all these cases automatically.
What is the difference between a proper fraction, improper fraction, and mixed number?
A proper fraction has a numerator smaller than the denominator (3/4, 1/7) — its value is between 0 and 1. An improper fraction has a numerator equal to or larger than the denominator (7/4, 5/5) — its value is 1 or greater. A mixed number is an improper fraction rewritten as a whole number plus a proper fraction (1¾). All three represent the same quantities; the choice of form is stylistic.
Why does dividing fractions use "keep-change-flip"?
Dividing by a fraction is the same as multiplying by its reciprocal because of how division and multiplication are inverse operations. (a/b) ÷ (c/d) = (a/b) × (d/c) = (a×d)/(b×c). "Keep" the first fraction, "change" division to multiplication, "flip" the second fraction. This is a shortcut that follows directly from the definition of division as multiplication by the multiplicative inverse.
How do I find the LCD (Least Common Denominator) to add fractions?
LCD(b, d) = (b × d) / GCD(b, d). For 1/4 + 1/6: LCD = (4×6)/GCD(4,6) = 24/2 = 12. Then: 1/4 = 3/12, 1/6 = 2/12, sum = 5/12. When denominators share no common factors, their LCD is simply their product. The Operate mode in this calculator shows the LCD step automatically for every addition and subtraction.
Why is 0/5 = 0 but 5/0 undefined?
Zero divided by anything (except zero) is zero: 0/5 = 0 because there are zero parts of five. But dividing by zero is undefined because there is no number that, when multiplied by zero, gives 5. It's not infinity — it's simply outside the domain of division. This calculator catches zero denominators and shows an error rather than returning a misleading result.
When should I use a mixed number vs an improper fraction?
Mixed numbers are more intuitive in everyday contexts: "I need 2½ cups of flour" is clearer than "I need 5/2 cups." Improper fractions are easier to use in calculations — adding, multiplying, and dividing improper fractions requires fewer steps than working with mixed numbers. The standard practice is to convert to mixed number form for final presentation of results, and use improper fractions while calculating.