How to use the flying geese cutting calculator
- Choose four at a time (the no-waste method) or one at a time, and inches or centimeters.
- Enter the finished width and finished height of one unit, and how many units you need. For four at a time, the width must be exactly twice the height.
- Leave the seam allowance blank for a quarter inch, or open More options to change it.
- Read the cut sizes, rounded up to the next eighth of an inch (or tenth of a centimeter), and the number of squares to cut.
Formula
four at a time, large square = W + 2 x seam x (1 + sqrt 2)
four at a time, small square = H + seam x (2 + sqrt 2)
one at a time, rectangle = (W + 2 x seam) by (H + 2 x seam), two squares of (H + 2 x seam)
In the no-waste method one large square is cut on both diagonals for four geese, and four small squares are cut once on the diagonal for the eight corner triangles. The cut sizes keep a seam allowance on all three sides of each triangle, which is where the factors 1 + sqrt 2 and 2 + sqrt 2 come from.
Twelve units that finish 6 by 3 inches
With a finished size of 6 by 3 and a quarter inch seam, the large square is 6 + 0.5 x 2.4142 = 7.2071 inches, which rounds up to 7 1/4. The small squares are 3 + 0.25 x 3.4142 = 3.8536, rounded up to 3 7/8. Twelve units need 3 large squares and 12 small squares, and each unit trims to 6 1/2 by 3 1/2 inches.
Cutting one at a time instead, each unit needs a 6 1/2 by 3 1/2 rectangle and two 3 1/2 inch squares: 12 rectangles and 24 squares.
Four at a time or one at a time
Four at a time is quick and wastes nothing, but only makes units twice as wide as they are tall. The sizes are rounded up a little so that there is room to trim each unit to its exact size after sewing. One at a time works for any shape, such as a goose three times as wide as tall, and uses more fabric.
The measurements match the way a flying geese unit is built: a large triangle for the goose and two smaller triangles on its sides for the sky. For the matching half-square corners, see the Half Square Triangle Calculator.
Check with a test unit
Seam allowances differ a little from one sewing machine and pressing method to another, so sew one unit before cutting everything. If it comes out slightly small or large, adjust the seam allowance under More options. For the size of a whole block, use the Quilt Block Size Calculator, and to cut strips from fat quarters, the Fat Quarter Cutting Calculator.
More layout tools
For other layouts and cutting sizes, try the Quarter Square Triangle Calculator, Pillow Cover Size Calculator and Regular Polygon Calculator.
Assumptions and limits
- Finished sizes are those of the unit after it is sewn into a quilt, without seam allowance.
- The default seam allowance is a quarter inch (0.635 centimeters), and all seams use the same width.
- The four-at-a-time method makes units exactly twice as wide as they are tall.
- Cut sizes round up for trimming, and yardage is not calculated.
Frequently asked questions
Why does the width have to be twice the height?
The big triangle is cut from a square on both diagonals, which makes a right triangle with its base twice its height. A different shape needs the one-at-a-time method.
Why do some charts show slightly different numbers?
Charts round to a convenient fraction and may add a bit more for trimming. This page shows the exact figure first and then rounds up to the next eighth of an inch.
What does the trim size mean?
After sewing, the unit is a little oversize. Trim it to the finished width and height plus two seam allowances, so that it fits the seams in the quilt top.
Can I use metric?
Yes. Choose centimeters. The seam allowance defaults to 0.635 cm, which is a quarter inch, and the cut sizes round up to the next tenth of a centimeter.