Quilts set on point: setting triangles and size

A block set on point is turned to stand on a corner. It then takes up its diagonal, the side times the square root of two, about 1.414 × the side, so a quilt on point is larger than the same blocks set straight.

The edges are filled with triangles. Side triangles have their long edge on the outside of the quilt, and that edge should be on the straight grain so that it does not stretch; they are cut by slicing a square twice, corner to corner, which gives four. The square is the block's diagonal plus an inch and a quarter. The four corner triangles have their short edges outside and are cut by slicing a smaller square once: the block's side divided by the square root of two, plus seven eighths of an inch.

Neither figure lands on a ruler mark, so they are rounded up, and sources round differently: one worked example goes to the next eighth, a popular chart to the next quarter and in places further. The calculator shows the raw figure and lets you choose the mark. A slightly large triangle is no problem, because the edge of the quilt is trimmed square after the top is sewn.

For a layout counted as blocks along the top edge and blocks down the side, the rows between hold one block fewer. The side triangles number twice the blocks across less one, plus twice the blocks down less one, and every square gives four.

Chart: square for side setting triangles, by block size and rounding

Each cell is the square to cut twice corner to corner for the finished block size in its row, rounded up to the next quarter inch, the next eighth, or not at all.

	Round the squares up to
Finished block size	The next quarter inch	The next eighth of an inch	No rounding
4 in	7.000 in	7.000 in	6.907 in
5 in	8.500 in	8.375 in	8.321 in
6 in	9.750 in	9.750 in	9.735 in
7 in	11.250 in	11.250 in	11.149 in
8 in	12.750 in	12.625 in	12.564 in
9 in	14.000 in	14.000 in	13.978 in
10 in	15.500 in	15.500 in	15.392 in
12 in	18.250 in	18.250 in	18.221 in
14 in	21.250 in	21.125 in	21.049 in
16 in	24.000 in	24.000 in	23.877 in

Work out your own numbers: Setting triangles calculator

Chart: square for corner setting triangles, by block size and rounding

Each cell is the square to cut once corner to corner for the finished block size in its row. Two squares give the four corners.

	Round the squares up to
Finished block size	The next quarter inch	The next eighth of an inch	No rounding
4 in	3.750 in	3.750 in	3.703 in
5 in	4.500 in	4.500 in	4.411 in
6 in	5.250 in	5.125 in	5.118 in
7 in	6.000 in	5.875 in	5.825 in
8 in	6.750 in	6.625 in	6.532 in
9 in	7.250 in	7.250 in	7.239 in
10 in	8.000 in	8.000 in	7.946 in
12 in	9.500 in	9.375 in	9.360 in
14 in	11.000 in	10.875 in	10.774 in
16 in	12.250 in	12.250 in	12.189 in

Work out your own numbers: Setting triangles calculator

Chart: width of a quilt set on point, by block size and blocks across

Each cell is the width of the pieced quilt before borders for the block size in its row and the number of blocks along the top edge in its column.

	Blocks across
Finished block size	2 pcs	3 pcs	4 pcs	5 pcs	6 pcs
6 in	17.0 in	25.5 in	33.9 in	42.4 in	50.9 in
8 in	22.6 in	33.9 in	45.3 in	56.6 in	67.9 in
9 in	25.5 in	38.2 in	50.9 in	63.6 in	76.4 in
10 in	28.3 in	42.4 in	56.6 in	70.7 in	84.9 in
12 in	33.9 in	50.9 in	67.9 in	84.9 in	101.8 in
14 in	39.6 in	59.4 in	79.2 in	99.0 in	118.8 in

Work out your own numbers: Setting triangles calculator

Used by

• Setting triangles calculatorSide and corner triangles for a quilt set on point.

Sources

• C&T Publishing: quilting tips, setting triangles
• Phoebe Moon: piece a quilt on point