Calculators

Make half-square triangles in the size you want

The Half-square triangles calculator gives the square size to cut for HSTs two, four or eight at a time, how many squares you need, and the size to trim them to.

Where to find it

Studio top bar → Calculators → Half-square triangles. Also at quiltler.com → Calculators, and in the Calculators tab of the iPhone and iPad app.

Open the HST calculator
On the Half-square triangles calculator, choosing 8 at a time (magic 8) and typing 24 HSTs gives 6 squares cut at 7 3/4 inches for 3 inch finished half-square triangles, each trimmed to 3 1/2 inches

How to do it

  1. Press Calculators in the studio's top bar and choose Half-square triangles. It opens on eight 3″ HSTs, two at a time, with the answer already in the You need card.
  2. Type the size you want them to finish at in Finished HST (inches).
  3. Choose a Method: 2 at a time, 4 at a time or 8 at a time (magic 8).
  4. Type How many HSTs you need.
  5. Read the card: how many squares to cut, the Cut size, and the size to trim each one to.

Good to know

  • Two at a time is the finished size plus ⅞″. Four at a time is the finished size plus 1¼″.
  • Trim every unit to the finished size plus ½″, its size with seam allowance, so the points land where they should.
Who can use it
Free, no account needed on the web
Where it works
Web studio · quiltler.com · iPhone & iPad

This guide answers

  • What size square do I cut for half-square triangles?
  • How do I make 3 inch HSTs?
  • What size squares for magic 8 HSTs?
  • How many squares for 24 HSTs?
  • What do I trim my HSTs to?
  • How do I make HSTs four at a time?