Proportion Calculator
Three tools in one: solve any proportion with one unknown, convert units through proportions, or work a map scale both directions. Every answer comes with the cross-multiplication shown step by step.
Solve a proportion
Enter three known terms and mark the unknown with x. The calculator cross-multiplies and checks itself.
a/b = c/d → a × d = b × c
Unit converter
Conversions are proportions in disguise: 1 unit over its equivalent, scaled to your value.
1/factor = value/x → cross-multiply
Map scale
1 map unit represents a fixed number of real units. Go from map to real, or real to map.
1/scale = map/real → cross-multiply