How Many Quilt Blocks Do I Need For...

"How many quilt blocks do I need to make a ‘fill-in-the-blank’ size quilt?" is perhaps the most frequently asked question submitted by readers of this website.

We're going to make it simple for you. Choose a size. Then download and print the answer. The math's already done!

To use these cheat sheets effectively, you need to know the basics:

• Is my mattress the standard size?

• What is the depth of my mattress?

• Do the drops listed cover my mattress the way I want them to?

If you answer yes to all, please continue.

On this page, you'll find cheat sheets for seven standard mattresses, along with instructions how to read the charts.

Let's get started.

Chart Basics: Straight Sets

At this time, the cheat sheets are for blocks set edge-to-edge in straight rows and columns.

Each bed size has its own 3-page cheat sheet, labelled at the top with the name and standard mattress dimensions.

The Finished Block Size is in the far-left column. This is the finished size of the blocks you are making.

The lines highlighted in blue (or gray if you printed in black and white) indicate how many blocks you need of a specific finished size.

The un-highlighted row directly beneath contains the actual dimensions using that layout and number of blocks—not including binding.

How the results are calculated

Here' what the numbers mean

How many quilt blocks you need for each row and column in your patchwork equals the quilt dimension (the number at the top of the column) divided by the Finished Block Size.

For a twin size, 65" wide, made with 4” blocks the math is:

65 ÷ 4 = 16.25

Since we only make whole blocks and want our patchwork to be at least 65” wide, we round up to 17 blocks (red arrow below).

For a twin with an 88" length with the same 4" blocks, the math is: 

88 ÷ 4 = 22

No rounding required because the numbers divided evenly.

Circled in purple below is the Total Number of Blocks you'll need for a Twin with a 13" drop on three sides with no pillow made with 4" finished blocks. The math is:

17 blocks x 22 blocks = 374 blocks

Underneath those blue (gray) highlighted rows are the resulting  dimensions.

These are calculated by multiplying the # of blocks in the previous blue line by the corresponding Finished Block Size.

EXAMPLE: If the Finished Block Size is 1-1/2” and the blue highlighted numbers are ‘44 × 59’, the calculations are:

44 × 1 ½” = 66” (blue arrow above)

59 × 1 ½” = 88 ½” (green arrow above)

The patchwork measures 66” x 88-1/2” before binding

Again, you can do these calculations on your calculator, but it sure is nice to have the work done for you or as a quick double-check, isn't it!

What the cheat sheets DON'T take into consideration

Shrinkage.

That means shrinkage from washing your patchwork—and if it’s a bed quilt, at some point it will get washed. Cotton batting and fabric can both shrink, especially if they’re not pretreated.

It also means shrinkage from quilting. Heavy quilting tends to pull in and shrink the finished size of your quilt.

Some quilters prewash their fabric but not their batting and vice versa. Some fabrics (higher thread count, in particular, like batiks) don’t shrinkage as much as cotton quilting fabric.

[Learn more about prewashing here and even more reasons here.]

What this means for you, the Quiltmaker

If the size you’ve chosen barely covers the mattress, and covering the mattress is important to you, consider adding a block to each row or column for insurance.

In our example, instead of 12 × 17 blocks, you'd use 13 × 18 blocks, measuring 78” x 108” with a total of 234 blocks.

Another option is to add an outer border, sashing or possibly wider binding.

The final option is to do the calculations yourself. Use this worksheet, “Worksheet for Calculating Bed Quilt Sizes" as a guide.