In the meantime, I have noticed many amazing equilateral triangle quilts appear on blogs and on instagram (Emily made another, too, and it's only been, what? 6 weeks since the retreat?)

In case it's becoming a thing, I am going to present my thoughts on it here.

**Sizing:**

The triangles shrink left to right when you sew them together, but only lose 1/4" height top to bottom. And when you join rows (losing 3/4" total).

Mine are 7.5" high (which makes the sides 8 2/3" each - based on geometry), and I went with 18/row and 13 rows - which is a little over 6 feet wide, and 7.3 feet tall.

How many should you cut? Well, what kind of quilt do you want? How about an equation?

**quilt length = row # x (triangle height - 0.75)**

-Or, if you prefer not to do the algebra-

**triangle height = quilt length/row # + 0.75**

(The 0.75 is your seam allowances - 0.25" lost in row piecing + 0.5" lost in row joining.)

So, if you wanted a baby quilt, which to me is 3' x 4', and thought 8 rows would be cute, you would write down:

**triangle height = 48"/8 + 0.75 = 6.75"**

Half an equilateral triangle 6.75" high is a right triangle, and you can solve for the long side using geometry:

**side length = 2*height / √ 3**

in our example:

**side length = 2 * 6.75" / 1.732 = 7.8"**

So, to find out how many triangle in a row, you actually have to figure out how many pairs, because the upper half of a triangle is tiny, while its base is huge, but they average out if you pair them:

**number of triangle pairs =**

**quilt width /**

**(triangle side length - 0.5)**

(The 0.5 is your seam allowances, again.)

**number of triangle pairs = 36" / (7.8"-.5") .... roughly 5 pairs**, so about 10 triangles/ row, or 80 triangles for this 8 row quilt.

*alternately, if you want to solve for the number of triangles, you can use:

number of triangles = 2 * quilt width/ (triangle side length - 0.5)

**Cutting:**

I decided to use patterns from some of my Spoonflower fabrics for the demos. |

You want to have your triangle height running along the grain of the fabric, either the crosswise or the lengthwise grain is fine - depending either on convenience or on the pattern of the fabric. But the bottom side should be aligned on the grain, because, well, it is a triangle, and triangle edges are notoriously stretchy except where they run along the grain.

You'll notice that I didn't start my triangle cuts right at the edge, but left a margin. That is so I can save those pieces for row ends. However, you need not do this for every fabric you cut - with 60 fabrics, I could have up to 120 of these end caps, but with only 13 rows, I only need 26. (Although, one must note that unless you are using only solids, they are chiral; not every end cap will fit on every triangle. And it becomes even worse if the fabric is directional.)

**Piecing:**

step 1: make sure the grain is going in the right direction! |

You may be thinking that this is a good time to chain piece- well, don't. Your best chance to line up triangles (unless you have clipped all of them) is to leave a corner free. On that note, I found it helpful not to clip dog ears, too.

Line up your new triangle with free corner and the folded under dog ear. |

And when the row is finished, I still don't trim the dog ears, but use them for a guide to line the row up with its neighbor:

These seams do get very bulky, though. |

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