The UN Office for the Coordination of Humanitarian Affairs said Tuesday that a total of 392,000 people have fled their homes since the offensive began in October, but that 94,500 have since returned.
The International Organisation for Migration puts the number currently displaced at 302,400.
Many of the displaced live in large refugee camps just outside the city.
Iraqi forces declared eastern Mosul "fully liberated" in January but heavy fighting is still underway in the more densely populated western half. Of those who have fled, the IOM says nearly 236,000 come from western Mosul.