It's smaller than I thought it would be.

Mjolnir was one of three gifts made for Thor by the dwarves, and could hide inside his shirt.
https://en.wikipedia.org/wiki/Mj%C3%B6lnir"The final product is then presented to Thor, and its properties are described, as follows,
Then he gave the hammer to Thor, and said that Thor might smite as hard as he desired, whatsoever might be before him, and the hammer would not fail; and if he threw it at anything, it would never miss, and never fly so far as not to return to his hand; and if be desired, he might keep it in his sark, it was so small; but indeed it was a flaw in the hammer that the fore-haft was somewhat short. (Original: Þá gaf hann Þór hamarinn ok sagði, at hann myndi mega ljósta svá stórt sem hann vildi, hvat sem fyrir væri, at eigi myndi hamarrinn bila, ok ef hann yrpi honum til, þá myndi hann aldri missa ok aldri fljúga svá langt, at eigi myndi hann sækja heim hönd, ok ef þat vildi, þá var hann svá lÃtill, at hafa mátti serk sér. En þat var lýi á, ar forskeftit var heldr skammt.)
— The Prose Edda, translated by Arthur Gilchrist Brodeur (1916)."
The other 2 were Járngreipr: (Iron gripper) a glove to hold the hammer. When Thor's anger waxed the hammer grew white hot.
https://en.wikipedia.org/wiki/J%C3%A1rngreiprAnd Megingjörð (Power Belt) which doubled Thor's already immense strength.
https://en.wikipedia.org/wiki/Megingj%C3%B6r%C3%B0Not a fanciful idea.
Check the belt.
