19.2 kg42.3 lb
Thor’s hammer, Mjölnir, weighs 19.2 kg (42.3 lb) according to Marvel, a figure first printed on its 1991 Marvel Universe trading card for the hammer. That is not very heavy. Nobody else can lift it because of Odin’s enchantment, which lets only the worthy pick it up: that part is magic, not mass.
| Metal movie propabout 60 lb, the heaviest of four versions used on set | 27.2 kg60 lb |
|---|---|
| Mjölnir in the comics42.3 lb, Marvel’s 1991 trading card | 19.2 kg42.3 lb |
The number traces back to card #128, “Thor’s Hammer”, in Marvel Universe Cards Series II (1991). It lists Mjölnir as made of uru, a fictional Asgardian metal, weighing 42.3 lb and measuring 22.7 inches (about 58 cm) long. The comics themselves almost never state a weight, and the Marvel Database notes that it is uncertain whether the card’s figures count as canon. Even so, it is the only specific weight we could trace to Marvel, and it is the one everyone quotes.
In 2013 materials scientist Suveen Mathaudhu used the card’s weight and size to work out a density of about 2.13 g/cm³. That is lighter than aluminium (2.71 g/cm³), which would make uru a very light metal that is also close to indestructible. Even so, 42.3 lb is only about twice the 20 lb (9.1 kg) head of a heavy-duty sledgehammer.
Because of a spell, not because of its weight. Since its first appearance in Journey into Mystery #83 (1962), the hammer has carried Odin’s enchantment: “Whosoever holds this hammer, if he be worthy, shall possess the power of Thor.” To anyone who is not worthy it will not budge, as if it were impossibly heavy, but the hammer itself still weighs 42.3 lb.
The films keep the same rule. In Thor (2011) Odin casts the enchantment when he banishes Thor to Earth, and later films show even the Hulk failing to lift it. Vision hands it to Thor without effort in Avengers: Age of Ultron, and Steve Rogers wields it in Avengers: Endgame.
In February 2013 astrophysicist Neil deGrasse Tyson tweeted that Mjölnir weighs as much as a herd of 300 billion elephants, on the idea that it is made of neutron star matter. The tweet was widely reported, and the huge figures you still see online trace back to that idea. No Marvel source gives a number anything like it.
The mix-up comes from the hammer’s origin story. In Thor (2011) Odin says it was “forged in the heart of a dying star”, and in Avengers: Infinity War (2018) Thor says the dwarves’ forge at Nidavellir harnesses a neutron star. As Mathaudhu put it at the time, the hammer was forged in a dying star, not of one: the star is the furnace, and the metal is uru.
The original Mjölnir comes from the Prose Edda, written down by Snorri Sturluson in 13th century Iceland. The dwarf brothers Eitri and Brokkr forged it after Loki bet his head that they could not beat the gifts made by other dwarves. Loki, disguised as a fly, stung Brokkr on the eyelid while he worked the bellows, and the hammer came out with a handle that was too short.
The myths give it no weight at all. They say it never misses, always flies back to Thor’s hand and can shrink small enough to carry inside his shirt. Thor wears iron gloves (Járngreipr) to handle it and a belt of strength (Megingjörð). About 1,000 small hammer pendants from the Viking Age have been found across Scandinavia.
The Marvel films never give a weight. Prop master Russell Bobbitt has said the metal prop weighs about 60 lb (27 kg), and lighter fiberglass, hard rubber and soft rubber copies are used for most shots and stunts.
No. In both the comics and the films it is made of uru, a fictional Asgardian metal. The dying star (a neutron star in Avengers: Infinity War) is where it was forged, which is why the “300 billion elephants” figure does not hold up.
Anyone Odin’s enchantment judges worthy. In the films that includes Vision, Steve Rogers and Jane Foster. In the comics, Beta Ray Bill proved worthy and Odin later gave him a hammer of his own, Stormbreaker.
Marvel has not published a weight for it that we could find. In Avengers: Infinity War it is an axe forged from uru at Nidavellir, with a handle made from Groot’s arm. In the comics, Stormbreaker is Beta Ray Bill’s hammer.
Marvel’s 1991 trading card gives 22.7 inches, about 58 cm. In the Norse myth its handle is famously short, because Loki distracted the dwarf working the bellows while it was being forged.
Last checked October 3, 2026.
