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Mixed Number Calculator

Reduction

Fraction Simplifier

Simplifying a fraction means dividing its numerator and denominator by their greatest common factor (GCF) until nothing more can be divided out. Type any numerator and denominator below and watch the prime factorization, the GCF, and the reduced result update instantly.

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Fraction

Result

View step-by-step working

    Method

    The Prime-Factorization Method

    Worked Example — 86/24

    Break the numerator and denominator into prime factors, multiply together whatever primes they share to get the GCF, then divide both parts by it.

    1. Factor the numerator and denominator

      86 = 2 × 43  ·  24 = 2 × 2 × 2 × 3

    2. Find the primes shared by both

      Only one 2 in common

    3. Multiply the shared primes

      GCF = 2

    4. Divide numerator and denominator by the GCF

      86 ÷ 2 = 43  ·  24 ÷ 2 = 12

    86/24 = 43/12

    Simplifying 86/24 to 43/12 by dividing by the GCF 86 over 24 becomes 43 over 12 when both the numerator and the denominator are divided by their greatest common factor of 2. 86 24 ÷ 2 43 12

    More Examples

    Simplifying Fractions of Different Shapes

    One division does it

    18/24 = 3/4

    GCF(18, 24) = 6, so both parts divide down in a single step.

    Already in lowest terms

    5/9 = 5/9

    5 and 9 share no common factor above 1 — there's nothing to divide out.

    Even numerator and denominator

    8/12 = 2/3

    Dividing by 2 alone would only reach 4/6 — the full GCF is 4.

    Larger numbers

    42/56 = 3/4

    GCF(42, 56) = 14.

    Numerator divides denominator

    7/49 = 1/7

    When the numerator is a factor of the denominator, the GCF is the numerator itself.

    Negative fraction

    −15/40 = −3/8

    The sign carries straight through — only the size gets divided by the GCF.

    Why It Matters

    Why Bother Simplifying at All?

    A fraction and its simplified form are never mathematically different quantities — 2/4 and 1/2 land on the exact same point on a number line, and either one is a technically correct way to write that value. What changes is only how easy the number is to read, compare, and work with. Simplest form is the conventional way to report a final answer for exactly that reason: 1/2 communicates the size of the quantity at a glance, while 2/4 forces a reader to notice a shared factor before the size registers.

    Teachers, textbooks, and standardized tests treat an un-simplified fraction as an incomplete answer even when the value is correct, because lowest terms is the single canonical way to write any given fraction. There's only ever one simplified form for a value — 2/4, 3/6, and 50/100 all simplify to the same 1/2 — which makes lowest terms the natural way to check whether two fractions that look different are actually equal.

    Simplifying also makes every later calculation easier. Comparing 12/18 and 14/21 at a glance is hard; comparing their simplified forms, 2/3 and 2/3, is immediate — they're identical. Adding, multiplying, or converting a fraction to a decimal all involve smaller, easier arithmetic once the numerator and denominator have already been reduced, which is why simplifying is usually the very last step of a calculation rather than something skipped until later.

    None of this changes the underlying value being described. Simplifying a fraction is a change in presentation, not a change in size — the same reason a recipe writes "1/2 cup" instead of "50/100 cup" even though both instructions would produce an identical result in the mixing bowl.

    Common Mistakes

    Where Simplifying Goes Wrong

    Quick Reference

    Fractions Simplified to Lowest Terms

    Search or scroll this table for the simplified form of frequently seen fractions — useful for checking homework or double-checking a mental calculation.

    Common fractions reduced to their simplest form
    FractionSimplified
    2/4 1/2
    3/6 1/2
    4/8 1/2
    5/10 1/2
    4/6 2/3
    6/9 2/3
    6/12 1/2
    8/12 2/3
    9/12 3/4
    10/15 2/3
    12/16 3/4
    12/18 2/3
    14/21 2/3
    15/20 3/4
    15/25 3/5
    16/20 4/5
    16/24 2/3
    18/24 3/4
    18/27 2/3
    20/30 2/3
    21/28 3/4
    22/33 2/3
    24/32 3/4
    24/36 2/3
    25/100 1/4
    28/42 2/3
    32/48 2/3
    36/48 3/4
    40/60 2/3
    45/60 3/4

    Questions

    Frequently Asked Questions

    Questions specific to simplifying fractions with prime factorization, not already covered elsewhere on the site.

    What does it mean for a fraction to be in "simplest form"?

    A fraction is in simplest form — also called lowest terms — when its numerator and denominator share no common factor larger than 1. 3/4 is in simplest form because 3 and 4 share no common factor; 6/8 is not, because both are divisible by 2.

    Why do 2/4 and 1/2 represent the same value if the numbers are different?

    Dividing both the numerator and denominator by the same nonzero number scales a fraction without changing what it represents, the same way cutting a pizza into 4 slices and taking 2 covers the exact same amount as cutting it into 2 slices and taking 1. 2/4 and 1/2 sit at the identical point on a number line — simplifying only changes how that point is labeled, never where it sits.

    How can I tell if a fraction is already fully simplified?

    Find the greatest common factor of the numerator and denominator. If that GCF is 1, the fraction is already in lowest terms and nothing more can be divided out. A quick sanity check: if the numerator is odd, the fraction can never be simplified by dividing by 2, since an even denominator would need an even numerator to share that factor.