Quilt math
The sums behind every quilt.
How big, how much fabric, what size to cut. Each guide gives the answer first, then a calculator, then how it’s worked out, so you can check it with a pencil.
Sizes and yardage
How big to make it, and how much to buy for the top, the back and the binding.
Standard quilt sizes: crib to king
A quilt size chart from crib to king, the US mattress sizes they fit, and a calculator from your mattress, drop and pillow tuck to a finished size.
CalculatorHow much fabric do I need for a quilt?
A quilt yardage calculator: pick a size, a block and a layout, and get the fabric to buy for each color, the backing and the binding, to the ⅛ yard.
CalculatorQuilt backing calculator
How much backing fabric to buy for any quilt, seamed down the middle or across, or 108″ wide. Worked out to the ⅛ yard, with a 4″ overhang.
CalculatorQuilt binding calculator
How many binding strips to cut and how much fabric to buy for any quilt, straight or on the bias. 2½″ strips by default, worked out to the ⅛ yard.
CalculatorBatting sizes for every quilt
Which batting package or how much off the roll for any quilt: the usual crib to king package sizes, and the batting to buy, 4″ bigger on every side.
CalculatorFinished vs unfinished size, and where the ¼″ goes
Finished vs unfinished block size explained: why a 12″ block is 12½″ before it’s sewn in, and how much bigger to cut squares and triangles.
Width of fabric (WOF) explained
What WOF means in a quilt pattern, how wide quilting cotton is, why we trim 2″ of selvages, and when 108″ wide backing is the better buy.
Shrinkage and pre-washing: how much extra to buy
Should you pre-wash quilt fabric, and how much extra to buy if you do. A calculator for shrinkage, the sums behind it, and how to test your own fabric.
Calculator
Units and cutting
The size to cut for the size you want, for the units most blocks are made of.
Half-square triangles: what size to cut
What size to cut half-square triangles: finished + ⅞″ two at a time, and the sizes for four and eight at a time. A chart from 1″ to 12″ and a calculator.
CalculatorQuarter-square triangles (hourglass units)
What size square to cut for quarter-square triangles and hourglass units: finished + 1¼″, or + 1½″ to trim. With a size chart and a calculator.
CalculatorFlying geese size chart
Flying geese cut sizes for every finished size: no-waste four at a time (goose + 1¼″, sky + ⅞″) and stitch and flip. A chart and a calculator.
CalculatorHalf-rectangle triangles: what size to cut
What size rectangles to cut for half-rectangle triangles (HRTs), worked out exactly for any finished size, with a size chart and a calculator.
CalculatorSnowball and stitch-and-flip corners
What size to cut snowball corners: the corner’s finished size and ½″, sewn on stitch and flip. With a snowball block chart, bonus triangles and a calculator.
CalculatorHow to resize a quilt block
Make a quilt block bigger or smaller: scale the finished sizes, then add the seams. Real cutting lists at 12″, 9″, 6″, and sizes that cut cleanly.
Calculator
Layouts
Blocks on point, sashing between, borders around.
Setting and corner triangles for on-point quilts
Setting triangle size for any block on point: side triangles from a square the diagonal + 1¼″, corners half the diagonal + ⅞″. A chart and calculator.
CalculatorOn-point quilt size calculator
How big an on-point quilt is: blocks across and down times the block’s diagonal (side × 1.414), plus borders. A size chart and a calculator.
CalculatorSashing and cornerstones calculator
How big a quilt is with sashing, how many strips and cornerstones to cut and how much fabric to buy, for any block size and layout. A calculator and charts.
CalculatorQuilt borders: how to measure and cut them
How to measure a quilt for borders, how long to cut them, butted or mitered, and how much fabric to buy. A border calculator and a size chart.
Calculator
Precuts
Fat quarters, jelly rolls, layer cakes and charm packs: what they hold and how far they go.
Fat quarter and fat eighth sizes
A fat quarter is 18″ × half the width of fabric: 18″ × 21″ once the selvages are off. Fat eighths, quarter yards, and what each one cuts.
How many fat quarters for a quilt?
A 60″ × 72″ throw of 4½″ squares takes 17 fat quarters; a queen, 35. A chart for every bed size, and a calculator.
CalculatorJelly roll quilts: how big a quilt one roll makes
One jelly roll of 40 strips makes a 48″ × 60″ Rail Fence top. A throw takes 2, a queen 3. Charts, the jelly roll race, a calculator.
CalculatorLayer cake quilts: sizes and how many you need
One layer cake of 42 10″ squares makes a 57″ × 66½″ top. A throw takes 2, a queen 3. Charts and a calculator.
CalculatorCharm pack quilts: sizes and how many you need
One charm pack of 42 5″ squares makes a 27″ × 31½″ top. A crib quilt takes 3, a throw 6. Charts and a calculator.
CalculatorHoney bun and mini charm quilts: what one makes
A honey bun is about 40 strips 1½″ wide; one makes a 36″ × 40″ top. A mini charm pack of 2½″ squares makes 12″ × 14″.
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Beyond squares
Hexagons, wedges and diamonds, measured the way their templates are.
Hexagon sizes for English paper piecing
A 1″ hexagon is about 1¾″ across the flats and 2″ point to point; cut its fabric from 2⅝″ strips. A chart from ½″ to 2″, and a calculator.
CalculatorDresden plate math: blades and angles
20 blades of 18° for a 15″ Dresden Plate: 6½″ strips, the ruler’s 2⅞″ and 9⅜″ lines, 21 a strip. A calculator for any plate.
CalculatorLone Star quilt math
A Lone Star of 5 diamonds a side from 2½″ strips is about 48¼″ across and trims to 49½″. Sizes, strip sets and a calculator.
Calculator
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