Very roughly, a TEU is a 20Ft connex. Subtracting the tare weight of a connex from the max weight, a 20 ft box can hold 47,600 lbs or 21.6 tonnes.
A "normal" VLCS (Very Large Container Ship) can hold 15,000 ish cans, but they do not plan for all the can's to be full to capacity. You gotta look up the ship's deadweight tonnage to compare to that sailing dingy.
As WLJ posted the new ULCS's that are coming out dwt 240,736 tonnes.
A more "normal" sized VLCS, the Ever Given of Suez Canal fame dwt like 220,000 tonnes.