You would need $21 million to attack Bitcoin for a day

It now costs just north of $21 million per day to sustain a 51% attack on the Bitcoin network for a whole day, according to data from Messari Pro. As it stands, this cost makes Bitcoin almost eight times more expensive to attack than Ethereum, which would set you back almost $2.7 million to attack for a whole day.

In brief, a 51% attack—also known as a majority attack—is arguably one of the biggest threats to many blockchains, since it sees a group of miners, or a single nefarious entity secure more than half of a network’s hash rate in order to gain control over the associated proof-of-work (POW) blockchain.

In order to attack Bitcoin, you would need to get enough mining machines to control half the Bitcoin hash rate. And that means matching the hash rate that’s already there. Messari estimates the cost of an attack based on how much it would cost to rent this much hash power on NiceHash, a crypto mining marketplace.

Comparatively, an attacker can gain control over the