Map scale
Turn a map line into a real trip
Read the key, match the map units, then stretch the distance.
Read the key
Match map units
Stretch distance
Check the scale
Read the key
A map key connects two different worlds.
The short line is on paper. The long distance is in real life.
Two measurementsOne connection
1 cmon the map
↔
15 kmin real life
Read it aloudKeep the sides matched
Every 1 cm on this map stands for 15 km of real distance. A map centimetre is a group, and each group is worth 15 km.
1 map cm ↔ 15 real km
Compare with the 1 cm key2.5 × 1 cm = 2.5 cm
Two full partsOne half part
1 part1 × 1 cm
1 part1 × 1 cm
½ part0.5 × 1 cm
Real route2.5 parts × 15 km each
Each full part is 15 kmHalf a part is 7.5 km
1 part1 × 15 = 15 km
1 part1 × 15 = 15 km
½ part0.5 × 15 = 7.5 km
Record what the picture showedMap → real
Use 2.5 copies of the scale key
2.5 × 15 km = 37.5 km
Because 2.5 cm = 2.5 × 1 cm, use the same multiplier on the matching real distance: 2.5 × 15 km.
Reverse checkDoes one map unit still match?
÷ 2.5 map centimetres
37.5 km ÷ 2.5 cm = 15 km/cm
The result matches the key: 1 cm represents 15 km. Our distance is consistent.
Ranger stationBeach
Map distance: 1.75 in
Key: 0.5 in ↔ 1.5 mi
mi per in
miles
First make one map inch. Then scale 1.75 inches.
Work on your whiteboard: first find the miles for 1 inch, then find the miles for 1.75 inches. Submit when both steps are ready.
Solution, part 1Make one map inch
0.5 in
↔
1.5 mi
÷ 0.5 on both sides
1.5 ÷ 0.5 = 3 mi per in
Solution, part 2Stretch 1 inch to 1.75 inches
× 1.75 map inches
3 mi/in × 1.75 in = 5.25 mi
Check: 5.25 ÷ 1.75 = 3 mi per in. That matches the normalized key.
Your map routineWorks with whole numbers, decimals, and fractions
1Read the keyKeep map and real units on their own sides.
2Make one map unitDivide both sides when the key does not start at 1.
3Scale the distanceMultiply the real value by the measured map units.
4Reverse-checkReal distance ÷ map distance should recreate the key.