Albert Barnes Commentary Matthew 14:20

"And they all ate, and were filled: and they took up that which remained over of the broken pieces, twelve baskets full." — Matthew 14:20 (ASV)

And they did all eat, and were filled. This was an undoubted miracle. The quantity must have been greatly increased to have supplied so many. He who could increase that small quantity so much, had the power of creation; and he who could do that could create the world out of nothing, and had no less than Divine power.

Twelve baskets full. The size of these baskets is unknown. They were probably such as travellers carried their provisions in. They were used commonly by the Jews in their journeys.

In travelling among the Gentiles, or Samaritans, a Jew could expect little hospitality. There were not, as now, public houses for the entertainment of strangers. At great distances there were caravansaries, but they were intended chiefly for lodging-places for the night, and not to provide food for travellers. Hence in journeying among strangers, or in deserts, they carried baskets of provisions; and this is the reason why they were furnished with them here.

It is probable that each of the apostles had one, and they were all filled. John 6:12 says that Jesus directed them to gather up these fragments, that nothing be lost: an example of economy. God creates all food; it has, therefore, a kind of sacredness; it is all needed by some person or another, and none should be lost.

See Barnes on "Matthew 14:13".