Quick answer: how to calculate a border
Finished width equals top width plus 2 times border width. Finished length equals top length plus 2 times border width. Side strips run the top length. Top and bottom strips run the finished width, including side borders. Total strip length equals 2 times side length plus 2 times top and bottom length. Strips are rounded up, and yardage to buy is exact yardage rounded up to the nearest 1/8 yard.
Example: a 50 by 60 inch top, 4 inch border, 44 inch usable fabric width, seam 0.5 inch. Finished size is 58 by 68 inches. Side strips are 60 inches each, top and bottom strips are 58 inches each, total strip length is 236 inches, strips needed are 6, exact yardage is 0.67 yards, yardage to buy is 0.75 yards.
Border width in this guide means finished width, the width you see after sewing. Cut width equals finished width plus seam allowance on both sides, so with 0.5 inch seam allowance a 4 inch finished border is cut 5 inches wide, and yardage in this guide uses cut width. Fabric width means usable width after removing selvages, not bolt width. If your pattern gives cut width, do not enter it as finished width, because finished size will then be overstated. Enter finished width in the calculator, and allow for seams when you cut, according to your pattern.
If you only need a number, use the Quilt Border Calculator. If you want to understand why that number is right, and when to change the method, read on.
What a quilt border does
A border is a strip of fabric sewn around the edge of a quilt top, after the main blocks are joined. It can be one plain strip, or several strips in different widths and colours. A border changes the finished size, it changes how the quilt looks on a bed, and it gives the binding a clean edge to finish against.
A border is not binding. Binding is the narrow strip that wraps the finished edge of the quilt sandwich. A border is part of the top itself, and it is added before backing, batting and quilting.
Choosing border width
There is no single correct border width. It depends on the quilt, the print and the bed it will cover. A few practical ways to choose:
- Start with the quilt. A small lap quilt often looks right with a 2 to 4 inch border. A large bed quilt can carry a 4 to 6 inch border without looking heavy.
- Check the print scale. A large print needs enough width to show, or it looks cut off. A small print can work in a narrow border.
- Think in finished size. If a quilt must fit a bed size, work backwards. Decide finished size first, then border width is the difference between top size and finished size, divided by two.
- Try more than one border. A narrow inner border in a strong colour, with a wider outer border in a quiet fabric, often looks more finished than one very wide border.
Step by step: how to calculate a border
Step 1: Measure the quilt top
Measure the finished top, pressed flat, in two places for width and two places for length. Use the larger number for each. If the top is uneven, square it up first. A border cannot fix a wavy top. It will only follow the wave.
Step 2: Add border width to get finished size
Finished width equals top width plus 2 times border width. Finished length equals top length plus 2 times border width. Border width is added on each side, so it is counted twice.
Step 3: Work out strip lengths
For straight borders, side borders are attached first. Each side strip length equals top length. Top and bottom borders span the full finished width, including side borders. Each top and bottom strip length equals top width plus 2 times border width.
Step 4: Add all four strips and work out strips needed
Total strip length equals 2 times side strip length plus 2 times top and bottom strip length. Compare total length with fabric width. If it 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. Round strips up.
Step 5: Convert strips to yardage
Fabric length to buy equals strips times cut width. Cut width equals finished border width plus seam allowance on both sides, because each strip loses one seam allowance where it joins the quilt top and one where it joins the next border or binding. 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 Quilt Border Calculator with your own top size, border width and fabric width. It uses the same steps as this guide, and it shows finished size, strip lengths, strips needed and yardage together.
Worked example: a lap quilt
Take a lap top that measures 50 by 60 inches. Add a 4 inch border. Finished width is 50 plus 8, which is 58 inches. Finished length is 60 plus 8, which is 68 inches.
Side strips: 2 strips, each 60 inches long. Top and bottom strips: 2 strips, each 50 plus 8, which is 58 inches long. Total strip length: 2 times 60 plus 2 times 58 equals 236 inches.
With 44 inch fabric and 0.5 inch seam allowance, strips needed equal 1 plus the ceiling of (236 minus 44) divided by 43.5, which is 6 strips.
Fabric length to buy: 6 times 4 equals 24 inches. Exact yardage: 24 divided by 36 equals 0.67 yards. Yardage to buy, rounded up to the nearest 1/8 yard, equals 0.75 yards.
With 108 inch fabric, the same border needs 3 strips, and yardage to buy is 0.38 yards. Wide fabric uses fewer strips, but it is often priced differently, so compare price per yard, not only total yards.
Border width table, our own computed table
This table uses a 60 by 80 inch top, 44 inch usable fabric width, and seam 0.5 inch, and it is computed from the same strip rule as the calculator, not copied from another site. Finished size, total strip length, strips, and buy yardage are all shown, so you can check any row by hand.
| Border width, finished | Finished size | Total strip length | Strips | Yardage to buy |
|---|---|---|---|---|
| 2 in | 64 by 84 in | 288 in | 7 | 0.63 yards |
| 4 in | 68 by 88 in | 296 in | 7 | 1.00 yard |
| 6 in | 72 by 92 in | 304 in | 7 | 1.38 yards |
Note that strips stay at 7 across these three rows, because total strip length grows slowly while border width grows. Yardage still grows, because each strip is wider. Do not judge fabric need from strip count alone.
How to make sure your result is correct
- Finished size check. Finished width must equal top width plus 2 times border width, and finished length must equal top length plus 2 times border width.
- Strip length check. Side strips must equal top length, and top and bottom strips must equal top width plus 2 times border width, for straight borders with side borders first.
- Total and strips check. Total strip length must equal 2 times side length plus 2 times top and bottom length, and strips must be rounded up, never down.
- Buy versus exact check. Buy yardage must never be below exact yardage. If it is, you rounded the wrong way.
- Finished versus cut check. Confirm whether your pattern gives finished width or cut width before you enter a number. Entering cut width as finished width overstates finished size.
- Usable width check. Enter usable fabric width after removing selvages, not bolt width, or strip count can be too low near a boundary.
Measuring and attaching checklist
Measure through the centre of the top, not only along the edge, and measure in three places, top, middle and bottom, because edges can stretch. Use the centre measurement for strip length, and ease the top gently to fit, instead of pulling the border to fit, or the finished border will wave. Pin at the ends and the middle first, then pin between, press seams toward the border unless a pattern says otherwise, and check for waviness before quilting. If the top is not square, square it up first, because a border follows the edge it is sewn to.
Straight borders compared with mitered borders
| Type | Corner | When it suits |
|---|---|---|
| Straight border | Square corner, side borders first | Most quilts, scrappy borders, and borders with pieced corners |
| Mitered border | 45 degree corner, like a picture frame | Striped or directional fabric, and a formal framed look |
Do not use straight border lengths for a mitered border. Mitered corners need extra length for the 45 degree join. Use the Mitered Border Calculator for that job.
Multiple borders, one at a time
If you want more than one border, calculate the first border, then use its finished size as the top size for the next border. Repeat for each border, one at a time. This method works for any number of borders, and it avoids the common mistake of adding all border widths to the original top at once and then cutting strips to the wrong length.
Example: start with a 50 by 60 top. Add a 2 inch inner border, and finished size becomes 54 by 64. Add a 4 inch outer border to that 54 by 64 size, not to the original 50 by 60, and finished size becomes 62 by 72.
Common mistakes that waste fabric or spoil a border
- Cutting top and bottom borders to top width. They must span finished width, including side borders, or corners will not meet.
- 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.
- Adding a border to an uneven top. Square up the top first, or the border will follow the uneven edge.
- Using straight lengths for mitered corners. Mitered borders need a different calculation, and straight lengths will come up short at the corners.
Tips for a border that lies flat
Cut border strips on the lengthwise grain when you can, because it stretches less than crosswise grain, which helps long borders stay straight. Measure through the middle of the top, not along the edge, because edges can stretch. Pin at the ends and the middle first, then ease gently, instead of pulling the border to fit. Press seams toward the border, unless a pattern says otherwise, so the top stays smooth under quilting.
Calculate your own border now
Use your top size, border width and fabric width in the calculator, and check the result against the steps in this guide.
Open the Border CalculatorFrequently asked questions
It does not need to match exactly, but it should sit well with the top in colour and weight. A border that is much heavier than the top can make the quilt drape unevenly. A border print should also work at the width you plan to cut.
It depends on quilt size, print scale and finished size you need. A lap quilt often looks right with a 2 to 4 inch border, and a bed quilt can carry a wider border. Decide finished size first if the quilt must fit a bed, then work border width backwards from that size.
No. A border follows the edge it is sewn to. Square up the top first, measure through the middle, and pin carefully, or the uneven edge will show in the finished border.
Lengthwise grain stretches less, so it suits long borders and helps them stay straight. Crosswise grain works too, but long strips will need joins, and each join loses seam allowance.
Do not stretch a strip to fit. Join a new piece, and use a diagonal join if you want less bulk at the seam. Check yardage before cutting, with the calculator above, so a shortage is found on paper, not at the cutting table.
Related guides and calculators
Next, read about How to Calculate Backing for the back of the quilt, and use the Binding Calculator for the finished edge. For a framed look, see the Mitered Border Calculator, and for border fabric alone, see the Border Yardage Calculator.