Hints and Tips 21 - How many strips do I need?-how to calculate the number of strips/units you need to make a border

When making the Redwork Woodland owl quilt I had to determine the number and best size to cut and stitch strips to fit the border of the quilt.

 

 

I wanted it to have an odd number of pieces so that the border ended with a dark coloured piece on each end of the strip

Once again I used the formula, this time working backwards.

Number of strips/ units= (Required border/strip length - 0.5) ÷ (strip/ unit width - 0.5)

 

 

Example 1
 I need strips to make a border that is 40 1/2 inches long and I would like to use 2 1/2 inch wide strips.

The calculation is: 

    (40.5 - 0.5)   ÷  ( 2.5 - 0.5)
   = 40 ÷  2
   = 20 strips
 

I would like to make an odd number of strips so I will make the strips a little smaller  2 1/4 inches 

 (40.5 - 0.5) ÷ ( 2.25 - 0.5)
   = 40 ÷  1.75
   = 22.8 strips

That is just a little under 23 so we will round up to 23 and that will give me the number of strips.

 

 

Example 2

I need to have a border of 65 inches long and I would like to make 3.0 inch pinwheels blocks
 

(65 - 0.5)  ÷  (3.0 - 0.5 )
=64.5  ÷ 2.5

= 25.8 pinwheels which we will round up to 26 pinwheels. 

 

 Example 3

 

If my border was 90 inches long and I wanted to put in 5 inch pinwheels,

The number I need is

(90 - 0.5)  ÷  (5.0 - 0.5)
= 89.5  ÷ 4.5
= 19.9  or rounded up 20 pinwheels.
 

 I have included a fraction to decimal conversion table for common values