Fiji is about 870 times bigger than Nauru.

Nauru is approximately 21 sq km, while Fiji is approximately 18,274 sq km, making Fiji 86,919% larger than Nauru. Meanwhile, the population of Nauru is ~9,811 people (933,926 more people live in Fiji).
Tip: This to-scale comparison of Nauru vs. Fiji uses the Mercator projection, which distorts the size of regions near the poles.
Our free app, MapSize by MyLifeElsewhere — compare any two places, to scale on your mobile device.