Quick answer: how to calculate binding
Perimeter equals 2 times finished width plus 2 times finished length. Binding length needed equals perimeter plus extra. Strips are rounded up, and yardage to buy is exact yardage rounded up to the nearest 1/8 yard, never down.
Example: a finished quilt 68 by 88 inches, strip width 2.5 inches, usable fabric width 44 inches, seam 0.5 inch, extra 12 inches. Perimeter is 312 inches, binding length needed is 324 inches, strips are 8, exact yardage is 0.56 yards, yardage to buy is 0.63 yards.
Measure after quilting, not from the original top size, because borders and quilting change finished size. Fabric width means usable width after removing selvages, not bolt width. Extra means the length for joining strips, turning corners, and closing the final join. The calculator default extra is 12 inches, and you can change it, but do not set it to zero unless you have a reason, because the final join still needs overlap.
If you only need a number, use the Binding Calculator. If you want to understand why that number is right, and why other calculators give different numbers, read on.
What quilt binding is
Quilt binding is the strip of fabric that wraps the raw edge of the quilt sandwich, after quilting. It covers the top, batting and backing edges together, and it gives the quilt a clean, durable finished edge. Without binding, the layers would fray and separate with use and washing.
Binding is not a border. A border is part of the quilt top, added before quilting. Binding is added after quilting, around the finished edge. Binding is also not backing. Backing is the bottom layer of the quilt sandwich. Binding wraps all three layers together at the edge.
Straight grain, bias, single fold and double fold
| Type | What it means | When it suits |
|---|---|---|
| Straight grain binding | Strips cut along the grain of the fabric | Straight edges, most quilts |
| Bias binding | Strips cut on the diagonal, so they stretch | Curved edges, scallops, and round quilts |
| Double fold binding | Strip folded in half lengthwise before sewing, so the finished edge has two layers | Most quilts, especially quilts that will be used and washed often |
| Single fold binding | Strip used as a single layer, folded over the edge once | Light quilts, and some decorative edges, where a thinner finish is wanted |
This guide, and the Binding Calculator, are for straight grain binding. For curved edges, use the Bias Binding Calculator. The calculation method is the same in outline, perimeter plus extra, strips, then yardage, but bias strips are cut differently, so use the bias tool for bias work.
Choosing binding strip width
Binding strip width is the cut width of each strip, not the finished width on the quilt edge. It depends on the binding method you use, and on how wide you want the finished binding to look.
- Double fold binding: a common cut width is 2.5 inches. Folded in half, it gives a finished binding that is wide enough to cover the edge and fold neatly to the back.
- Narrower binding: a narrower cut width gives a narrower finished edge, but it is harder to fold and sew neatly, especially for beginners.
- Wider binding: a wider cut width gives a wider finished edge, and it can be a design feature, especially in a contrasting fabric.
- Check your method first. Decide on single fold or double fold, and on finished width, before calculating yardage, because yardage follows cut width. Changing cut width after buying fabric changes yardage.
Step by step: how to calculate binding
Step 1: Measure finished quilt size
Measure the finished quilt, after borders and quilting, pressed flat, in two places for width and two places for length. Use the larger number for each. Binding goes around the finished edge, so measuring from the original top will give a perimeter that is too small.
Step 2: Work out perimeter
Perimeter equals 2 times finished width plus 2 times finished length. This is the distance binding must travel around the quilt, before any extra is added.
Step 3: Add extra for joins, corners and overlap
Binding length needed equals perimeter plus extra. Extra covers joining strips together, turning corners, and the final overlap where binding ends meet. The calculator default is 12 inches. Change it if your method needs more or less.
Step 4: Work out strips needed
If binding length needed fits in one fabric width, you need 1 strip. If not, each extra strip adds fabric width minus seam allowance, because seam allowance is lost at each join. Strips are rounded up. A part strip still needs a full strip of fabric.
Step 5: Convert strips to yardage
Fabric length to buy equals strips times binding strip width, because each strip is binding strip width wide. Divide fabric length by 36 to get exact yardage in inch mode. Round up to the nearest 1/8 yard. Rounding up covers cutting and trimming, and it is not waste.
Try it with the calculator: Use the Binding Calculator with your own finished quilt size, binding strip width and fabric width. It uses the same steps as this guide, and it shows perimeter, binding length needed, strips needed and yardage together.
Worked example: a twin quilt
Take a finished twin quilt that measures 76 by 96 inches. Use binding strip width 2.5 inches, fabric width 44 inches, seam allowance 0.5 inch, extra 12 inches.
Perimeter: 2 times 76 plus 2 times 96 equals 344 inches.
Binding length needed: 344 plus 12 equals 356 inches.
Strips needed: 356 inches does not fit in 44 inches. Each extra strip adds 43.5 inches. Strips equal 1 plus the ceiling of (356 minus 44) divided by 43.5, which is 9 strips.
Fabric length to buy: 9 times 2.5 equals 22.5 inches. Exact yardage: 22.5 divided by 36 equals 0.62 yards. Yardage to buy, rounded up to the nearest 1/8 yard, equals 0.63 yards.
Binding yardage table, our own computed table
This table uses finished quilt size, strip width 2.5 inches, usable fabric width 44 inches, seam 0.5 inch, and extra 12 inches, and it is computed from the same strip rule as the calculator, not copied from another site. Changing strip width, usable width, or extra changes the answer, so use the calculator for your own numbers.
| Finished quilt size | Perimeter | Binding needed | Strips | Yardage to buy |
|---|---|---|---|---|
| Baby 36 by 48 in | 168 in | 180 in | 5 | 0.38 yards |
| Lap 50 by 60 in | 220 in | 232 in | 6 | 0.50 yards |
| Twin 68 by 88 in | 312 in | 324 in | 8 | 0.63 yards |
| Full 80 by 92 in | 344 in | 356 in | 9 | 0.63 yards |
| Queen 90 by 108 in | 396 in | 408 in | 10 | 0.75 yards |
| King 108 by 108 in | 432 in | 444 in | 11 | 0.88 yards |
Note that Full and Twin are close in buy yardage, but they are not the same, because strip count and exact yardage differ before rounding. Do not copy a row for a different size.
Why other calculators give different answers
Other calculators differ mainly in two inputs, not in the perimeter formula, which is the same everywhere. First, extra allowance is not standard: some use 10 inches, some 12 inches, some 15 inches, and some add a percentage instead of inches. Second, fabric width is not standard: some use bolt width, some use usable width, and usable width can be 40 to 44 inches for the same bolt. A larger extra or a smaller usable width gives more strips and more yardage, and that does not mean one calculator is wrong. It means the inputs differ. In this guide, extra is 12 inches by default and fabric width is usable width, and both are stated so you can compare fairly. If another calculator gives a different answer, check its extra and its fabric width first.
How to make sure your result is correct
- Finished size check. Enter finished size after quilting, not original top size, or perimeter will be too small.
- Perimeter check. Perimeter must equal 2 times finished width plus 2 times finished length.
- Extra check. Binding needed must equal perimeter plus extra, and extra must cover joins, corners, and final overlap.
- Strips check. Strips must be rounded up, and each extra strip must add usable width minus seam allowance, not full bolt width.
- Buy versus exact check. Buy yardage must never be below exact yardage. If it is, you rounded the wrong way.
- Usable width check. Enter usable fabric width after removing selvages, not bolt width, or strip count can be too low near a boundary.
Joining and attaching binding, in brief
- Join strips end to end, usually with a diagonal join, so the seam lies flatter than a straight join, and press seams open.
- Fold the joined strip in half lengthwise for double fold binding, and press, so the fold stays even while sewing.
- Sew binding to the front of the quilt, with raw edges aligned, leaving a tail at the start for the final join, and turning corners with a fold at each corner.
- Fold binding over the edge to the back, and finish by hand or by machine, keeping the fold even and the corners square.
- Join the ends where they meet, with enough overlap to close the loop cleanly, without stretching the binding to fit.
This is a summary, not a full binding tutorial. If you have never bound a quilt, practice joining and turning a corner on a small sample first, with the same strip width you plan to use.
Common mistakes that leave binding short
- Measuring from top size, not finished size. Borders add size, so binding measured from the top will be too short.
- Forgetting extra length. Perimeter alone is not enough. Joins, corners and final overlap need extra length, and the calculator default is 12 inches for that reason.
- Forgetting seam allowance at joins. A joined strip loses seam allowance at each join, so usable length is less than fabric width times strips.
- Rounding yardage down. Rounding down can leave you a few inches short at the end of a strip, when the quilt is already quilted and hardest to fix.
- Stretching binding to fit. Stretching pulls the edge out of shape. If binding is short, add a piece, or recalculate and buy more, instead of stretching.
Calculate your own binding now
Use your finished quilt size, binding strip width and fabric width in the calculator, and check the result against the steps in this guide.
Open the Binding CalculatorFrequently asked questions
Yes, many quilters do, and it gives a clean, quiet edge. It also means binding fabric must be bought separately from backing yardage, because backing yardage is calculated for the back of the quilt, not for binding strips. Add binding yardage to your shopping list, even if the fabric is the same.
Leave a tail at the start and at the end, so the ends overlap. Join them with a diagonal seam, trim excess, and press, so the loop closes cleanly. Do not sew the ends together by stretching one end to meet the other, or the edge will pucker.
Both work, and it is a design choice. Matching binding gives a quiet edge and lets the quilt design lead. Contrasting binding frames the quilt, like a border, and it can pick up a colour from inside the quilt. Decide before buying, because it affects which fabric you shop for.
Do not stretch it to fit. Add a piece with a diagonal join, and press the seam open, so the join lies flat. It is better to have one extra seam than a stretched, wavy edge. Next time, check perimeter, extra length and strip count before cutting.
Not always, but double fold is more durable, because the finished edge has two layers of fabric. Single fold is thinner, and it suits light quilts and decorative edges. For quilts that will be used and washed often, double fold is the safer choice.
Related guides and calculators
Next, read Bias vs. Straight-Grain Binding for curved edges, and use the Bias Binding Calculator for bias work. For the back of the quilt, see How to Calculate Backing, and for the finished edge itself, use the Binding Calculator.