Attacking Bitcoin Costs Hundreds of Millions an Hour — Attacking Ethereum Classic Costs Under $15,000

A 51% attack happens when a single actor or group gains control of more than half a network's computing power, letting them rewrite recent transaction history, including double-spending the same coins, DEXTools explains.

The cost of pulling this off varies wildly between networks. For Bitcoin, a one-hour attack would run into the hundreds of millions of dollars — the network is simply too large to touch. For Ethereum Classic (ETC), a top-cap PoW coin, a one-hour attack costs under $15,000; for Litecoin, it's $75,000-90,000 an hour, KuCoin notes.

Why smaller networks are so cheap to attack: hash-rate rental marketplaces let attackers rent computing power for a few hours instead of buying hardware outright. If a small blockchain uses a common algorithm like SHA-256, an attacker can rent enough power to temporarily outweigh the entire network.

What this means in practice: Ethereum Classic has already suffered successful 51% attacks in 2019 and 2020, costing exchanges millions through double-spending. The rule is simple: the smaller a network's hashrate (or staked capital), the cheaper it is to cheat — and that applies to nearly every coin outside the top two by market cap.

This article is for informational purposes only and does not constitute investment advice.