The bars show why it works. Once both fractions are cut into the same size pieces, adding is just counting pieces. Subtraction works the same way.
How to use the fraction visualizer
Type a fraction in each box, such as 3/4 or 2/5. You can also type mixed numbers with a space, like 1 1/2, whole numbers, decimals like 0.6 and negative values. Choose an operation and SeeFractions draws both fractions, works out the answer and draws the result. Switch the model between bars and circles to match the one used in class. Swap flips the two fractions, which is handy for subtraction and division.
Under the answer you will find its decimal and percentage, the mixed number for improper fractions, a numbered list of steps, and a chain of equivalent fractions. Every step uses whole numbers only, so answers are always exact rather than rounded.
Why visual models help
Most fraction mistakes come from treating the numerator and denominator as two separate numbers. Models make the denominator visible as the size of the pieces and the numerator as how many pieces you have. Once students see that 1/3 and 1/6 are different size pieces, the need for a common denominator before adding is obvious. Teachers often move from bars to circles to number lines; SeeFractions covers the first two and the fraction wall bridges to comparing many fractions at once.
Private by design
SeeFractions has no accounts and no server-side processing. All arithmetic happens in this browser, and your last inputs are saved in local storage on this device only.
Frequently asked questions
Why can’t I add the denominators?
The denominator names the size of the pieces. 1/2 + 1/3 is not 2/5; you need equal pieces first, so 3/6 + 2/6 = 5/6.
What is the least common denominator?
The smallest number both denominators divide into. For 4 and 6 it is 12.
How do I add mixed numbers?
Type them as 1 1/2; SeeFractions converts them to improper fractions first and shows the mixed answer.
Is SeeFractions free?
Yes. All calculations, models and printing are free with no sign-up.
Is anything stored online?
No. Everything runs in your browser, and your last inputs are saved only on this device.