A ratio expresses how quantities relate to each other. Simplifying finds the smallest whole-number version of that relationship; scaling applies it to a real-world total — useful for mixing ingredients, splitting costs, or dividing resources proportionally.
Simplifying divides every part of the ratio by their greatest common divisor (GCD), so the same proportion is expressed in the smallest possible whole numbers — 8:12 and 2:3 describe the same relationship, but 2:3 is the simplest form. Decimal parts (e.g. 2.5:3.75) are first scaled up to whole numbers before the GCD is applied, then reduced the same way.
Scaling shares a real total across the ratio's parts in proportion. Each part's share of the total is its value divided by the sum of all parts, multiplied by the target total — so a 2:3 ratio scaled to 25 gives 10:15, since 2 and 3 parts out of 5 map onto 10 and 15 out of 25. Scaled figures are rounded to 2 decimal places.
Use "+ Add a third part" for ratios with three components, such as a 2:3:1 concrete mix or a three-way cost split. Both simplifying and scaling work the same way with three parts as with two — the GCD or the proportional share is just calculated across all three values.