Two-letter initial signatures
First initial, last initial: the shortest mark that still says who signed.

Two initials are the shortest signature most organisations will accept, and the reason is recognition: the reader is not spelling out a name, they are matching a shape against the one they expect.
Which letters earn their place
Two letters is the usual answer, three when your name is common. Two-letter initial signatures work because the reader is not decoding anything: they are recognising a shape they have seen before, at the bottom of a page they already trust.
The two letters need different weights. If both are the same size and pressure, the mark reads as a monogram; give the first letter the height and let the second carry the exit stroke.
Make the short mark hard to copy
Anything short is quick to imitate, so the defence is not length but habit: an unusual join between the letters, a fixed baseline, a stroke that always ends in the same place. Consistency is the part a copyist cannot see.
It is ideal for pages that need initialling and for approvals that happen twenty times a day, which is exactly where a full signature starts to fall apart.
Where initials work best
Initials belong where space is short and repetition is high — initialling each page of a contract, marking a drawing, signing off an internal approval. For a first signature on a legal document, most people still want the full mark.
You can build any of these in the browser: open the Signature maker, draw or type your name, and place the result straight onto a PDF or Word file. Nothing is uploaded — the document never leaves your device.