Quilty Math

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Here are some fun figures I shared during my recent Modern Quilt Guild webinar on Quilty math. If you’d like to view the webinar, please join the Modern Quilt Guild and log into the community site. The webinar is located under the resources tab.

Average Comforter Sizes:

  • Crib 40” x 55”
  • Twin 65” x 88”
  • Queen 86” x 95”
  • King 105” x 95”

Your quilt will shrink! Add 2”-3” more.

HSTSize to Cut Half-Square Triangles

Add 7/8″ to your finished square size and cut in half on the diagonal once.


QST Cutting

Size to Cut Quarter-Square Triangles

Add 1 1/4″ to your finished square size and cut in half on the diagonal twice.


Flying Gees Units

Flying Geese are twice as wide as they are tall so keep that ratio in mind. This example is a flying geese unit that finishes 3″ x 6″.

Flying GeeseThe two blue triangles are cut from one 3 7/8″ square (yielding 2 triangles – hst’s) and the grey triangle is cut from one 7 1/4″ square (yielding 4 triangles – qst’s).

Binding Formula For Straight of Grain Strips:

Perimeter +10″; then divide by 40″ for the total number of strips to cut.

Decimal conversions:

1/8 = .125    1/4 = .25    1/2 = .5   3/8 = .375     3/4 = .75    7/8 = .875


Size to Cut Triangles for On Point Quilts:

  • (Finished Block size x 1.414) + 1.25 = Size to cut squares for side triangles (QST)
  • (Finished Block size / 1.414) + 7/8 = Size to cut squares for corner triangles (HST)
  • Round up to the nearest 1/8″.
  • Side triangles are cut from 4 quarter squares.
  • Corner triangles are cut from 2 half squares.
Fin. Block Size Side Triangles Corner Triangles
3″ 5 1/2″ 3″
3 1/2″ 6 1/4″ 3 1/2″
4″ 7″ 3 3/4″
4 1/2″ 7 5/8″ 4 1/8″
5″ 8 3/8″ 4 1/2″
5 1/2″ 9 1/8″ 4 7/8″
6″ 9 3/4″ 5 1/8″
6 1/2″ 10 1/2″ 5 1/2″
7″ 11 1/4″ 5 7/8″
7 1/2″ 11 7/8″ 6 1/4″
8″ 12 5/8″ 6 5/8″
8 1/2″ 13 3/8″ 7″
9″ 14″ 7 1/4″
9 1/2″ 14 3/4″ 7 5/8″
10″ 15 1/2″ 8″
10 1/2″ 16 1/8″ 8 3/8″
11″ 16 7/8″ 8 3/4″
11 1/2″ 17 5/8″ 9 1/8″
12″ 18 1/4″ 9 3/8″
12 1/2″ 19″ 9 3/4″

EQClick here to download the Ice Crystals design into your EQ7 software.

(C) 2014 Christa Quilts Inc. For personal use only.

Ice CrystalsQuilt Planner

My friend Amy Ellis has put together a PDF worksheet that you can purchase which will help you keep track of your math. To view it in action, click here.

20141120_quilt_planner

12 thoughts on “Quilty Math

  1. Lizzie says:

    Fabulous to have both resources! If I were living nearby, I’d be at your lecture! thanks so much especially for the info on angles and how much you lose (need to add) with those 🙂

  2. Jo Ann Moulds says:

    Math is the worse part of quilting for me so I do appreciate all your great info. I usually keep making a sample block till I get to the size I need.

  3. Maresa Campbell says:

    Love this! Do you have a formula to figure out what size to cut flying geese? I can figure out the rectangle size but getting the two square sizes are hit and miss for me. Do you use the half square triange formula above? Thank you for this information. I have been looking for this information!

  4. Carolyn says:

    Thank you Christa, this is really helpful. I think there may be an error in the on point triangles cutting table. I think the corner triangle for the 5½ inch finished block is incorrect at 4 1/8. Should it read 4 7/8?

  5. searchfamilies says:

    I have downloaded & save this, i must since i have had to put my EQ7 back on due to computer problems, i got this but when i go to my PJ i can’t find it i tried doing a search but can’t find it yet if i go in to EQ it under the exsisting projects just can’t seem to figure out where they being save to lol
    Hugs Janice

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