Scaled technical drawling help

Every square is 5mm. For a length of 25mm i have used 2.5 squares (so in my head a square represents 10 mm) If i have made my technical drawing consistently like that what scale did i actually use, i have confused myself.
(so a 150mm actual length would be 15 squares on my paper).

So 15 squares = 15 x 5 = 75 mm does that help?

so does that mean its a 1:2 or a 2:1 ratio? or something different?