People often send me photos of large rocks that they think might be meteorites. If it’s big, it’s probably not a meteorite. Here are some statistics.
This chart shows that the most common mass for a stony meteorite is in the range 128-256 grams (4.5-9 oz).
This chart shows that half of stony meteorites are less than 283 g (10 oz.) in mass. Only 10% are greater than 5400 g (12 lbs.)
Caveat 1: I took these data from the online database of the Meteoritical Society in November of 2010. The “mass” is the total mass of all stones of a meteorite. Large meteorites fragment as they come through the atmosphere and land, so these charts exaggerate the size of any given stone of a meteorite. That is, although 50% of meteorites are less than 283 grams in total mass, 50% of meteorite fragments are much less than 283 in mass. The numbers aren’t really known. For example, the largest meteorite represented here is Jilin, which had an estimated mass of 4,000 kg. The largest surviving fragment was 1170 kg. This is probably the largest know fragment of any stony meteorite. There were hundreds of smaller fragments.
Caveat 2: A large fraction of the meteorites represented here are from the Sahara Desert. Sometimes for Saharan meteorites, different fragments of a single meteorite are given different names. This “source of error” is probably minor.