The title Offa used on most of his charters was "rex Merciorium", or "king of the Mercians", though this was occasionally extended to "king of the Mercians and surrounding nations".
Gelar yang digunakan Offa di sebagian besar piagamnya adalah "rex Merciorium", atau "raja Mercia", meskipun ini kadang-kadang diperpanjang menjadi "raja Mercia dan negara-negara di sekelilingnya".