We needed some matching Spring/Summer dresses, so I turned to the easiest way to make them! (and very cost effective) All you need is a T-shirt and a sheet. (plus any embellishments you want)  I seriously made 3 of these dresses in less than a hour they are so easy!
Once you have your sheet (I use sheets a lot because they are a LOT of fabric for the price and the fabric is wider than other fabric you’d buy which makes them perfect for these dresses)
Fold it into quarters.  holding the corner where the middle of the sheet is folded (this will be where you cut out the waist hole) fold the 2 sides together keeping the middle corner at the top.
So now the fabric looks like a pie shape.  And the point is the middle of the sheet.

Now to figure out how to cut the waist hole out.
Take the T-shirt you’re going to attach the skirt to and measure the width where the skirt will be sewn on.  (lets say it’s 10 inches)  then multiply that number by 2 since you have a front & back of the shirt. (so 20 inches)
Next you’ll want a calculator-  put in 20 divided by Pi (3.14) which ends up being 6.369.  Then divide that number by 2= 3.184
So just round that number down to 3. (you can always cut a little more off, but you don’t want to cut too much off)
Now measure from the corner (the one that’s the middle of the sheet) 3 inches, this is where you will cut.

What I do is start cutting into one side and then fold the part I’ve already cut over the part that still needs to be cut keeping a straight line from the folded part to the point.

Once you have your point cut off you have the hole for the waist.  Now cut the same way for the length. Measure on who the dress is for how long you want the dress to be.  Measure from where the skirt will be attached to the shirt to however long you want the dress.  Then measure that many inches from the top where you just cut the waist down one side and cut the bottom in the same way.

Now you have a circle with a hole in the middle.  Turn the circle so the patterned (or right side) is against the front of the t-shirt.  The hole in the circle should match up identically with the circumference of the t-shirt.  If the skirt part is too small you can always fold it back up and cut a little more off making the hole slightly bigger.  Remember it’s always better to be able to cut more off again then to cut too much off.

Sew the skirt to the t-shirt, then hem the bottom of the skirt and you’re done!
You can sew on embellishments around the waist and the hem line if you like, or you can sew on a belt, lace or whatever else you like!

I made these dresses a longer- drop waist style for fun.  You can also do an umpire waist by just cutting the t-shirt shorter. I made some this style for our Christmas dresses.

These instructions are good for any size dress/t-shirt- I made them for my 1 year old, 11 year old, and myself.