Hexagon Quilt Calculator
Enter your target quilt dimensions and the finished side length of your hexagons. This calculator works out how many full hexagons and edge half-hexagons you need, the actual quilt top size, the cut square size including seam allowance, and the total fabric yardage. Switch between inches and centimetres at any time.
How hexagon quilts work
A hexagon quilt is built from regular six-sided patches arranged in a grid that staggers alternate columns by half a hexagon height. This offset is what creates the classic honeycomb look. Because the grid does not produce a perfectly straight edge, the perimeter of the quilt top is filled with half-hexagons, which are cut from the same square of fabric and trimmed. The finished quilt top is slightly different in size from the target dimensions you enter, because the hexagons only step in fixed increments of column spacing and row height.
How to measure your hexagon size
Hexagon size in quilting always refers to the finished side length of one hexagon - the distance from the centre of one flat edge to the midpoint of the opposite flat edge, not the point-to-point diagonal. For a hexagon with side s, the full width across the flats is s times the square root of 3 (about 1.732 times s), and the full height from point to point is 2s. Common finished sizes run from tiny 1/2" English paper piecing hexagons through 1", 1.5", and 2" sizes used in machine piecing, up to 3" or 4" for bold modern quilts. Smaller hexagons mean more pieces to cut and sew, but a finer, more intricate texture.
Cut square size and seam allowance
Each hexagon is cut from a fabric square whose side equals twice the finished hexagon side plus twice the seam allowance: cut size = 2 x (side + seam allowance). The standard quilting seam allowance is 1/4 inch (6 mm). So for a 1 inch finished hexagon, you cut 2.5 inch squares. For English Paper Piecing (EPP), these squares are wrapped over a paper template and basted; for machine piecing they are stamped and cut directly. Buying or printing hexagon templates for your chosen size gives a precise cutting guide. Always cut a few test pieces and sew a small sample before committing to full yardage.
Calculating fabric yardage
Once you know the total number of hexagon pieces and the cut square size, you can work out yardage. Divide the usable fabric width (typically 40-44 inches after removing selvedges) by the cut square size to find how many squares fit across one strip. Divide the total number of pieces by that per-strip count to get the number of strips, then multiply by the cut square size to find the total fabric length needed. Convert to yards (divide by 36) or metres (divide by 100). Add a waste buffer of 10-15% for pre-washing shrinkage, cutting errors, directional prints, and squaring up. If you are using multiple fabrics, the total yardage divides evenly among them, assuming equal distribution of colors across the quilt.
Standard quilt sizes
| Quilt type | Dimensions (in) |
|---|---|
| Baby / Crib | 36 x 52 |
| Lap / Throw | 50 x 65 |
| Twin | 65 x 95 |
| Full / Double | 80 x 95 |
| Queen | 86 x 100 |
| King | 106 x 106 |
Common quilt dimensions by bed type. Add 10-15% for overhang or use the calculator to fine-tune.
Frequently asked questions
What does "hexagon size" mean in quilting?
In quilting, the hexagon size refers to the finished side length of one hexagon - the length of a single edge of the six-sided shape. A 1-inch hexagon has each of its six sides measuring 1 inch in the finished quilt. This is different from the point-to-point diagonal (which is 2 inches for a 1-inch hexagon) or the flat-to-flat width (about 1.73 inches). Always confirm which measurement a pattern or template uses before cutting fabric.
Why do I need half-hexagons?
Hexagon grids stagger alternate columns by half a row, which means the left and right edges of the quilt are not straight. Half-hexagons fill those jagged side edges so you end up with a rectangular quilt top. You cut them from the same size square as your full hexagons and then trim along the centreline. The number of half-hexagons in this calculator is the count for the two long side edges; if you also want straight top and bottom edges, you may need partial pieces there as well.
Why does my actual quilt size differ from the target size?
Hexagons can only be placed in whole increments of column spacing and row height, so the calculator rounds up to the nearest whole column and row count. The result is a quilt top that is at or just above your target size. If you want to hit a specific finished size exactly, you can add a border after completing the hexagon top to make up any difference.
How much extra fabric should I buy?
A 10% buffer is a safe minimum for cutting errors and squaring up. If you plan to pre-wash your fabric (recommended for cotton), add 15% to account for shrinkage. Directional prints, stripes, or plaids that need to be fussy-cut should get at least 20% extra. The waste buffer selector in this calculator lets you choose the right level for your project.
Can I use this calculator for English Paper Piecing?
Yes. Enter the finished side length of your paper template as the hexagon side length. Cut squares at the size this calculator shows, wrap each square around a paper template, and baste the fabric over the edges. The hexagon counts, column and row numbers, and yardage figures all apply equally to hand EPP and machine piecing.
What is the difference between full hexagons and half hexagons?
Full hexagons are the regular six-sided pieces that make up the body of the quilt. Half hexagons are pieces cut along the centreline of a hexagon to fill the zigzag edges on the left and right sides of the quilt top. They use the same size cut square as a full hexagon, but you trim them in half after cutting. Some quilters substitute a straight strip for the edge fill instead of true half hexagons.
How do I calculate backing and batting?
The backing fabric is calculated separately from the top fabric. Take your actual quilt top dimensions from this calculator, add 4 to 6 inches to each side (2-3 inch margin all round for longarm quilting), and work out how many widths of fabric you need to cut and seam together to reach the backing width. Batting is cut to the same size as the backing. This calculator handles top fabric only; use a separate backing calculator for those figures.