Ισοψηφισμός (Isopsephy)

Ισοψηφισμός (Isopsifismós, from the Ancient Greek ἴσος, isos ["equal"] + ψῆφος, psephos ["pebble"]) is a system of converting Greek letters to defined numeric values.

Tool
https://hatch.kookscience.com/cipher/iso.php?cipher=el_1