To calculate a
scale factor for the size you want to enlarge or reduce your
plans too, just invert the scale of the plans you have - divided
by the inverted scale of the plans you wish to build from. For
example if your plans are 1/5 scale and you desire to go to 1/3,
simply divide 5 by 3. This result gives you a scale factor of
1.67 for 1/3 scale or 1.25 for quarter scale.

Since the maximum
paper size of the large copy machines I’ve seen at Kinko’s is
36", divide this by your scale factor to get the maximum size of
your current plan to be enlarged. So we divide 36 by 1.67 we get
21.6 for 1/3 scale and 28.8 for ¼ scale. If we cut the original
1/5 scale plans into strips not over 21.5", they can be joined
end to end and copied.

This calculator will help
you calculate the copier
magnification settings for scaling your aircraft model plans larger
or smaller.

Don't forget to
review our information sheet on Dynamically Scaled Values. This
contains formulas use by professional aircraft designers and my
help you in your redesign efforts.