Quilting calculators

What each tool solves

Start with the quilt size calculator to turn a block grid plus sashing and borders into finished inches, or to fit blocks to a twin/queen target. Use the quilt backing calculator for yardage and panel layout (default 4″ overhang per side for longarm prep). The binding calculator converts perimeter into strip count and fabric yards for your strip width. The HST calculator covers 2-, 4-, and 8-at-a-time starting-square sizes and yield.

How to measure the top

• Measure the finished quilt top after borders—not just the block grid on paper.
• For backing, add the overhang your quilter requests (FiberCalc defaults to 4″ per side; shops may ask for more).
• For binding, use the actual perimeter after quilting; quilting can draw the sandwich up slightly.
• Confirm usable fabric width (often ~40–42″ after selvages) before trusting panel counts.

Worked example: backing for a twin top

Quilt 60×80″, 4″ overhang → backing need 68×88″. On 42″-wide fabric, ceil(68 ÷ 42) = 2 vertical panels; cut length ≈ 88 × 2 = 176″, plus a little for the joining seam. 176 ÷ 36 ≈ 4.89 yards before you round up at the cutting table. Run the same numbers in the backing calculator to see panel orientation when horizontal seams would use less fabric.

Worked example: binding strips

Same 60×80″ quilt: perimeter = 2 × (60 + 80) = 280″. Add about 12″ join waste → 292″ of continuous binding. On 40″ usable width, ceil(292 ÷ 40) = 8 strips. At 2.5″ strip width, fabric ≈ 8 × 2.5 = 20″ ≈ 0.56 yards—buy a little more if you prefer continuous bias or wider strips.

Worked example: HST batch

Forty 3″ finished HSTs with the 8-at-a-time method need starting squares of 2 × 3 + 1.75 = 7.75″ and five fabric pairs. Classic 2-at-a-time uses 3 + ⅞ = 3.875″ squares and twenty pairs. The 4-at-a-time starting square is (finished + ½″) ÷ 0.64 (about 5.47″ for a 3″ finish) and always needs careful trimming because edges are on the bias.

Common mistakes

• Buying backing from the mattress size instead of the finished quilt top plus overhang.
• Cutting binding from the pre-quilted perimeter without re-measuring after quilting.
• Entering unfinished HST size into a finished-size formula (or the reverse).
• Ignoring selvage trim when counting how many strips fit across the width.

Guides and reference charts

Narrative how-tos: backing yardage guide, binding guide, and HST math guide. Size tables: standard quilt and mattress sizes. Related sewing tools for non-pieced yardage live on the sewing hub. Formula provenance and correction history: Methodology.