Your question was a very good one and this is all very good advice. However, the same problem occurs with the ruler. The lines on rulers are larger than the rotary cutter. Do you use the center of the line, the right side or the left?

The key is still consistency. You need to pick one and stay with it. Because not all rulers are the same, I do a test piece and measure after cutting. For example, if I want a 3 inch strip, I cut a test strip using the center of the line. I measure it to be sure it is 3 inches. If not, I move to the left or right accordingly. I use those colored tapes to mark the spot I need and stay with that mark for my project.

This takes more time, but saves me time in tearing out mistakes due to bad cuts. Good luck.

I usually lose approximately 1/2 inch with each seam (1/4 inch from each piece/side) and twice that makes one inch loss.

After sewing the two inch strips together, these are my approximate measurements.

1.75 + 1.5 + 1.75 = 5

(2 - 1/4) + (2 - 1/4 - 1/4) + (2 - 1/4) = 5

(Put that in the wrong place)

With three 2" strips you get 5"
With two 3" strips you get 5 1/2"

I can agree with those statements

:) :thumbup:

Math/arithmetic does come in handy now and then!

Turn the mat over and just use the lines on the ruler. I find using the lines on the mat make my cuts off.

Ok so I had a duh moment!! You are right! Will I be forgiven?

i took a class recently and the instructor said to always cut on the left of the line on your ruler and mat if you use mat. Her theory is that this accounts for the scant quarter inch. However, I have found that if I consistently line up with left of the line on either my cuts are more accurate. Consistency is the key

Each seam has 2 1/4" edges of fabric, so out of the first seam of the 1st and 2nd patches, you lose 1/4" off each square, making a total of 1/2" off the width with the 1st seam alone.

Sewing the first 2 sewn patches to a third patch takes another 2 1/4" edges, for another total of 1/2" lost off the width.

So after having sewn 3 patches together, you have lost 1" of overall width.

3 2" patches sewn in a row yield a 5" long strip.
.

I saw a quilting show with Alex Anderson where they talked about how to line up your ruler along the cut edge of the fabric to get an accurate measurement.
The line on the ruler should line up just past the cut edge of the fabric, not on top of it. In other words it butts up to the line but shouldn't extend into the line on the ruler.
I always use this method and find I get the most accurate cuts this way. :D

That's why I like the rulers with the thinnest lines printed on them.