I know for many of you, math is a four-letter word. In order for your projects to come out the right size and nice and flat, as well as being able to determine how much fabric to buy, you're gonna have to do a little bit of math. But relax - it's 3rd grade math, not calculus!! Having these formulas in your "toolbox" will allow you the freedom to plan and create any quilt in any size!
Let's start today with quilt blocks.
FACT: Most patchwork blocks are based on an evenly divisible grid. Can you visually see the even divisions in these quilt blocks?
Can you determine the GRID base for the following blocks?
|(1.) 6x6, (2.) 5x5, (3.) 4x4, (4.) 5x5, (5.) 4x4, (6.) 6x6, (7.) 5x5, (8.) 4x4|
Can you calculate the block sizes for the rest of the blocks shown above if the grid unit size is 2"? What about 3"? Here's a hint: Determine the underlying grid and multiply by the grid unit size.
Resizing Quilt Blocks
Once you have determined the grid base of a quilt block, you can resize the block by multiplying the grid by a new unit size, or by choosing a new finished size and dividing by the grid to create a new unit.
Huh? For example, look at the following block. The grid = 4x4, the small square = 2", and the finished size = 8".
To resize by the block by changing the Unit Size:
Grid x Unit Size = Block Size
What size will the block finish if the small squares are now 3"?
(Answer: 12" )
To resize by changing the Block Size:
Block Size / Grid = Unit Size
What size is the small square if the block now finished at 6"?
Is your head spinning yet? Just keep thinking in the grid, and you'll be fine. But blocks are the basis of most quilts, and having the power to create blocks in any size (instead of what your pattern or book tells you) gives you the freedom to create whatever size quilt you want! Isn't that liberating?
If any of this isn't clear, just drop me a comment and I'll try to respond. Next week - calculating quilt sizes!
EDITED 3/5:Cindy asked if I could provide the grid blocks with the actual grid overlaid on top of them. Please excuse my less than stellar drawing skills - but you should be able to see the blue lines on top of the quilt blocks.
Rebecca asked on Facebook how to calculate sizes for blocks that don't fit the "square" mold of basic quilt blocks, like Tumblers.
Here's my smart-aleck answer....EQ7. I use Electric Quilt Software to draw basic blocks and rudimentary quilt layouts because it's faster than graph paper and EQ does the math for me. I probably use one-tenth of its total capabilities, but it saves me time and brain cells when I'm drafting a new quilt.
But for Tumblers, here's how you plan a quilt.
The height of the row is easy. It is based on the measurement of the tumbler from top to bottom. Multiply the height by the number of rows to get your finished length measurement.
Here's a diagram showing how to calculate the width of the row (drawn in EQ7, I might add....).