QUILT PLANNING / BINDING
Straight-grain vs bias binding
Bias describes the direction a strip is cut in the fabric. A diagonal seam joining two strips does not change their grain direction.
Choose for the edge you are finishing
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| Feature | Straight-grain strips | Bias-cut strips |
|---|---|---|
| Cut direction | Along or across the grain | Approximately 45° to the grain |
| Typical use | Straight-edged rectangular quilts | Curved edges needing more flexibility |
| Yardage planning | Equal strips across usable width | Depends on the bias cutting layout |
| Planning tools | Main calculator | Separate diagonal-strip planner below the binding calculator |
Why a diagonal join is still straight-grain
Our calculator models strips cut across usable fabric width, then joined either straight across or at 45°. The diagonal joining option spreads the joining seam along the binding, but the strips themselves remain on the original grain. Selecting that option does not turn the result into a bias estimate.
Curved edges need a different plan
Bias-cut fabric has more give around curves. A curved project also needs its actual edge length measured; twice width plus twice length only describes a rectangle. Choose a bias-binding pattern or cutting method that specifies strip width, available fabric dimensions and expected yield.
Use our bias-strip planner for individual 45° strips cut from squares. It measures the rectangles that fit, discards end triangles and accounts for each join. It is separate from the straight-grain shopping list and does not model continuous tube binding.
Do not add an arbitrary percentage
There is no fixed percentage in this tool for converting straight-grain yardage into bias yardage. Separate diagonal strips and continuous bias from a square or rectangle have different layouts and waste. Work from the instructions for the chosen method rather than adding a guessed amount to this calculator’s result.
For a rectangular quilt
If your pattern calls for straight-grain strips, use the strip-count calculation and test the strip width. Confirm the edge finish before buying the fabric.
Read our calculation methods and limits. Examples use the same arithmetic as the calculators and are planning estimates, not independently field-tested sewing instructions. Confirm allowances with your quilter.