Quilting guide

How to set quilt blocks on point

Updated October 5, 2026 by Khokhar Sab

Turn each block 45 degrees and sew the quilt in diagonal rows. Fill the gaps along the sides with setting triangles cut from squares of the block size × 1.414 + 1¼ inches, cut twice corner to corner. Fill the four corners with triangles cut from squares of the block size ÷ 1.414 + ⅞ inch, cut once. For 8 inch blocks that is a 12⅝ inch square for the sides and a 6⅝ inch square for the corners.

What an on-point setting is

In a straight set, blocks sit in rows and columns with their sides parallel to the edges of the quilt. In an on-point set, each block is turned 45 degrees so it stands on one corner, like a diamond.

That leaves triangle-shaped gaps around the outside. Side setting triangles fill the gaps along each edge. Four corner triangles fill the corners. Together they turn the diamond layout back into a rectangle.

Why on-point quilts come out bigger

A block on point is measured across its diagonal, corner to corner. The diagonal of a square is its side × 1.414 (the square root of 2). An 8 inch block on point takes up 8 × 1.414 = 11.31 inches.

So the quilt center is the number of blocks along each edge times that diagonal. With 4 blocks across the top and 5 down the side, the center is 4 × 11.31 = 45.25 inches wide and 5 × 11.31 = 56.57 inches long.

The same 8 inch blocks in a straight set of 4 by 5 would make a 32 by 40 inch center. On point, you need more blocks too, because a second grid of blocks fills in between the first.

Counting the blocks and triangles

Count the full blocks as two grids. One grid has 4 × 5 = 20 blocks. The blocks that sit between them form a grid of 3 × 4 = 12. That gives 32 full blocks in all.

• Side setting triangles: one in each gap along the edges, which is 2 × (4 − 1) + 2 × (5 − 1) = 14.
• Corner triangles: always 4, one for each corner.

Each square you cut for side triangles gives 4 triangles, so 14 triangles need 4 squares, with 2 to spare. Each corner square gives 2 triangles, so you need 2 squares for the 4 corners. The on-point setting calculator does these counts for any layout.

Block counts for common on-point layouts

The table runs the same math for a few grid sizes with 8 inch blocks. The last column is the setting triangle fabric: the side and corner squares cut from 42 inch fabric with 10 percent extra, rounded up to ⅛ yard.

Patchwork Posse recommends an on-point setting when you need a larger quilt but have a limited number of blocks. The numbers back that up. In the 4 × 5 layout, each full block accounts for about 80 square inches of the quilt center, against 64 square inches for the same block in a straight set. The setting triangles fill the difference. The same source warns that the triangles can take a lot of fabric, and the last column shows it: 1 yard just for the triangles of a 45 by 57 inch center. Patchwork Posse suggests scraps or a favorite background fabric for them.

How to cut setting triangles

C&T Publishing gives two short formulas, and the calculator uses the same ones. It rounds each cut up to the next ⅛ inch.

1. Side triangles: multiply the finished block size by 1.414 and add 1¼ inches. Cut a square that size, then cut it twice from corner to corner to make an X. For 8 inch blocks: 11.31 + 1¼ rounds up to 12⅝".
2. Corner triangles: divide the finished block size by 1.414 and add ⅞ inch. Cut a square that size, then cut it once from corner to corner. For 8 inch blocks: 5.66 + ⅞ rounds up to 6⅝".

The C&T example for a 6 inch block comes to 9¾ inches for the side squares and 5⅛ inches for the corner squares, which matches the table below.

Some tutorials round at a different step. Artquiltmaker's on-point tutorial works a 16 inch block by rounding the diagonal up to 22¾ before adding 1¼ inches, which gives a 24 inch square. The calculator adds first and rounds once, which gives 24". For the corners the same tutorial gets 12⅜ inches against the calculator's 12¼". The rounded-early sizes are a little bigger, which is harmless, since you trim the edges straight after sewing. The tutorial also reminds you to use the finished block size: a 16 inch block measures 16½ inches before it is sewn in.

Why the two triangles are cut differently

Woven fabric is stable along its threads, which is the straight grain. Cut across the threads at 45 degrees, on the bias, and the edge stretches. AccuQuilt puts it plainly: you don't want a stretchy bias edge running around the outside of your quilt.

The cutting methods take care of this. When you cut a square twice into four triangles, the long side of each triangle is an edge of the original square, so it is on the straight grain. That long side becomes the outer edge of the quilt.

When you cut a square once into two triangles, the two short sides are the square's edges. On a corner triangle, those two short sides face outward and form the corner of the quilt. Swap the methods and you get a bias edge on the outside, which can stretch and ripple.

How to set blocks on point, row by row

1. Lay out all the blocks on point on a wall or floor. Place a side triangle at both ends of each row and a corner triangle at each corner.
2. Sew the quilt in diagonal rows. This layout has 8 diagonal rows, running from one corner to the opposite one.
3. Sew a side triangle to each end of a row. Its long edge faces out and becomes part of the quilt's edge.
4. Press the seams in each row the opposite way from the row next to it, so they nest when you join the rows.
5. Sew the rows together, matching the block corners.
6. Add the corner triangles last. Center each one on the end of its row before you sew.

To center a triangle on a block edge, Artquiltmaker folds both pieces in half and lines up the creases before sewing. Patchwork Posse points out that the triangle points stick out past the block once sewn. That is expected, and the extra comes off when you trim.

Setting a single block on point

You can also turn one block on point by itself, with a triangle on each side. The result is a bigger square block with the original standing on its corner. Patchwork Posse's method uses the corner triangle formula: divide the finished block size by 1.414, add ⅞ inch and round up. Cut two squares that size and cut each once from corner to corner, which gives four triangles.

For a 8 inch block, that is two 6⅝" squares. Sew triangles to two opposite sides first, press, then add the other two. The finished framed block is the old diagonal, about 11.31 inches. Patchwork Posse suggests rounding the squares up further, so you can square the framed block down to an even size afterward. Framed blocks sew together in straight rows, so you get the on-point look with no setting triangles around the edge.

Keeping the edges straight

The triangle edges that get sewn to the blocks are on the bias. Handle them gently and don't pull them as you sew, or they stretch out of shape.

The exact sizes leave very little room for error. If you want a margin, cut the triangle squares larger and trim the edges later. The calculator's oversize box adds the same amount to both squares. With 1 inch extra, the 8 inch blocks need 13⅝" side squares and 7⅝" corner squares.

After the top is sewn, lay a long ruler along each edge and trim it straight. Leave ¼ inch of fabric beyond the block corners for the seam that attaches the border or binding. If you trim right at the corners, the points get cut off.

Adding a border or binding

A border frames the diamonds and gives the quilt a plain edge. The calculator can add one and work out its strips. When you are ready to finish, see how to bind a quilt, or compare with a straight set in the sashing and cornerstones guide.

For the formulas in their original form, read C&T Publishing's setting triangle tips. AccuQuilt's article on setting triangles and bias explains the grain in more detail.

Sources and further reading

• C&T Publishing: setting triangle tips.
• Artquiltmaker: setting blocks on point.
• Patchwork Posse: how to make a quilt block on point.

Video tutorial

"Cutting Corner and Setting Triangles for Diagonal Sets" by National Quilters Circle, on YouTube. The video loads only when you press play.