Proof of Work vs Proof of Stake: Two Ways a Blockchain Agrees on the Truth
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5 min read
Imagine 10,000 strangers share one notebook. Anyone can write a line in it. No boss checks the lines. How do they agree on which version of the notebook is true?
That is the problem a blockchain has to solve. A blockchain is a shared record of who owns what. The rule a network uses to agree on that record is called a consensus mechanism. The two big ones are proof of work and proof of stake. Bitcoin uses the first. Ethereum uses the second.
This post explains both with simple pictures. No price claims. Just how they work and what they cost.
In proof of work, computers race to solve a puzzle. The puzzle has no shortcut. The only way to solve it is to guess, very fast, billions of times.
The first computer to solve it gets to add the next page (called a block) to the notebook. It also earns a reward. People who run these computers are called miners.
Think of a lottery where you buy tickets with electricity. More computers means more tickets. More tickets means a better chance to win.
Here is the key idea. Cheating is expensive. To rewrite old pages, a cheater would need to out-guess the whole network again and again. That would cost a huge amount of electricity and equipment. So the cost is the security.
On Bitcoin, the reward is 3.125 BTC per block since the April 2024 halving. A halving is a built-in cut of the reward, planned in advance (viaBTC). Miners' costs for power, space and machines did not fall when the reward did. That is why weaker miners get squeezed after each halving.
To see how the puzzle's difficulty adjusts, read our guide to Bitcoin mining difficulty and hash rate.
Proof of stake drops the race. Instead of burning electricity, you lock up coins as a deposit. This deposit is your stake. People who do this are called validators.
The network picks validators to propose and check new blocks. If they do the job honestly, they earn rewards. If they cheat, they lose part of their deposit. This penalty is called slashing.
On Ethereum, one validator needs a deposit of exactly 32 ETH (ethereum.org). Validators must also stay online and do their duties.
Think of a security deposit on a rented flat. You get it back if you behave. You lose some if you break things.
How big is the penalty? Ethereum.org says a single, isolated slashing for a 32 ETH validator burns about 0.0078 ETH at once. Then the validator is removed over roughly 36 days. The penalty grows if many validators misbehave in the same window, and in the worst case it can reach the full stake. Slashing is rare, and most cases so far came from accidents, such as running the same signing key on two machines (same source).
The two methods pay for security in different ways.
| Proof of work | Proof of stake | |
|---|---|---|
| What you put in | Machines and electricity | Locked coins |
| Who does the work | Miners | Validators |
| Cost of cheating | Win the race again and again | Lose your deposit |
| Main running cost | Power bills | Money tied up in the stake |
| Used by | Bitcoin | Ethereum |
Energy is the biggest gap. Ethereum moved from proof of work to proof of stake on 15 September 2022, in an upgrade called the Merge. Ethereum.org estimates this cut its energy use by about 99.95% (ethereum.org). That number is an estimate, and it was first projected before the Merge happened.
In proof of work, miners earn the block reward. They must also pay for power and machines. If the coin price falls and costs stay put, some miners lose money and switch off.
In proof of stake, validators earn rewards for their stake. Their main cost is the capital locked in the deposit. They do not need to buy power-hungry machines.
This matters for ordinary people. Staking is how many holders earn a yield. But yield is not free money. Your coins are locked, prices can fall, and slashing exists. Our guide to crypto staking yield and risk covers that side.
There is no clean winner. Each one trades one cost for another.
Proof of work has a long track record on Bitcoin. Its price is high energy use. Proof of stake uses far less energy. Its price is that rewards go to people who already hold lots of coins, and that your capital sits locked.
People argue about this a lot. What helps you is knowing which system a coin uses, because it changes the risks. A miner-heavy coin reacts to power costs and halvings. A staking coin reacts to how many coins are locked up and how rewards are set.
Now you know why Bitcoin and Ethereum behave as different kinds of networks. Open the Explore screener and compare coins side by side, using volatility and drawdown. Check if the two designs show up in how each coin moves.