Measuring

The first thing you need to do is learn how to read a ruler.

Rulers and Templates

Get a good acrylic ruler. My favorite is the Omni Lip Edge 4x36". 

You'll also need a 12" square ruler.

You need an Add A Quarter and Add an Eighth ruler to measure and cut 1/4" or 1/8" seams. They're also useful for adding a 1/4" or 1/8" to the edge of rulers.

The Quick Quarter ruler is a 1/2" wide and I use it a lot. It's great for adding a 1/2" to a 3" ruler.

The 1/2x6" ruler is one that I took out of a sliding depth gauge. On the back, it shows the decimal equivalent of fractions down to 64rths of an inch. It has helped me a lot in calculating formula ingredients.

I also have a 1" wide steel ruler. I can use it for adding 1" to a 3" ruler and use the quick quarter ruler for adding a 1/2".

Deluxe Corner Trimmer for cutting off dog ears.

A 360 degree swing arm protractor for getting exact angles and lining up angled seams.

A precision compass for drawing perfect circles of any size.

Tips

1) Use fabric weights to prevent fabric from shifting while cutting.

2) Place weights on your rulers or templates so you don't have to hold them down with your hands.

3) If you hold a square ruler or template with your hands, place your weight at the top of the ruler where it is most likely to shift.

4) Fabri-Tac is a clear rubber cement that will prevent rulers and templates from slipping. Apply it to the bottom of the template and let it dry.

5) Check and align straight seams and angles before sewing.

Measuring and the Scant 1/4"

Blocks end up crooked or shorter than expected because pieces are cut to the 1/2". Even though the seam allowance is a 1/4", you will loose 1/16" with every fold in a block. The scant 1/4" is a way of compensating for folds. The actual measurement of a scant 1/4" is 3/16". You may add 1/16" to every seam allowance while sewing by moving the needle to the right one decimal. However, you would have to sew with a zig-zag foot and your seams may not be straight. I believe that adding this 3/16" to the seam allowance when cutting is a better way. 0.250 + 0.187 = 0.44 + 0.250 = 0.69 which is just 0.06 or a hair shy of 1/16" less than a 3/4". Cut your pieces to the 3/4" and you'll end up with a 1/2" finished block.

Quilter's Math

Quilting and carpentry go together like peanut butter and jelly. I'm not just referring to building sewing furniture. Long before templates were invented and even before block patterns were printed, quilters used carpenter's math for drawing blocks and measuring cut pieces. Unfortunately, almost no one in the quilting world today knows how to use it. 

If there's one thing I can teach you, it's the simple concept of Square & True. Every quilt block is a 90 degree square, even if it contains circles or curves. There are exceptions in more advanced quilting methods, but I'm only dealing with simple block construction. Pythagorean's Theorem states, "the squared sum of two right angles is equal to the square of the hypotenuse." I didn't pay a damn bit of attention to geometry in high school because it wasn't applied to anything I was interested in. Now that I'm older and have an interest in both carpentry and quilting, it makes sense.

Follow the carpenters 3-4-5 formula: First, use a square to make sure you have a right angle. Beginning at the right angle, measure the length and multiply that number by itself. Do the same with the width. Add these two numbers together. This number is Square. Now measure the diagonal to get the hypotenuse. Multiply that number by itself to get the True value. If the two products are the same, you're block is Square & True.

Half Square Triangles

Don't bother with figuring half and quarter square triangles. There's an easier way. We all love the 1/2" cut, 2-1/2 being our favorite.

A 7/8" square will always result in a 1/2" pieced block. Here's an example: cut two 3-7/8" squares. Cut them in half on the diagonal and sew them together with a 1/4" seam allowance. You will end up with two 3-1/2" blocks.

1-7/8 = 1-1/2

2-7/8 = 2-1/2

3-7/8 = 3-1/2

4-7/8 = 4-1/2

5-7/8 = 5-1/2

Quarter Square Triangles

A 1/4" square will always result in a 1/2" pieced block. Here's an example: cut two 3-1/4" squares. Cut them in half along both diagonals and sew them together with a 1/4" seam allowance. You will end up with four 2-1/2" blocks.

3-1/4 = 2-1/2

4-1/4 = 3-1/2

5-1/4 = 4-1/2

6-1/4 = 5-1/2

There is some very simple math you need to know for determining the amount of yardage you need to buy and the number of strips you need to cut. It's a lot better to make a calculating error and catch it while planning than it is to make a cutting error or realize you didn't buy enough fabric. One yard of fabric is 36x44". You will loose 1 square inch when you cut off the selvage and straighten the edges so you end up with 35x43". These are the numbers you'll be working with. Strips are cut along the 43" width from left to right. 

Count the number of pieces in a block according to dimensions and color. Multiply this number by the number of blocks in the quilt. 9 x 14 = 126

To determine how many strips to cut for the number of pieces you need, multiply the number of pieces by the width of the piece. Divide the product by 43. 126 x 1.5 = 189". 189 / 43 = 4 strips + 4".

To determine how many strips you can cut per yard, divide 35 by the width of the strips. 35 / 2.5 = 14 strips per yard. A half yard equals 7 strips.

To determine how much yardage you need (over 1 yard) for the number of strips you have to cut, subtract the number of strips per yard from the number of strips you need. 20 - 14 = 1-1/2 yard.