Started at 1,000. Stablecoins and gold tokens excluded. Members are the ten largest coins at each update, and the divisor adjusts when they change so the line stays continuous.
Countdown
Bitcoin halving
Every 210,000 blocks, the reward for mining new Bitcoin is cut in half.
Calculators for prices, market caps, history and risk, using live data.
History
Past investment
What money put into a coin on a past date is worth today.
Your investmentSame money in BitcoinMoney put in
Steady buying
DCA simulator
Buying a fixed amount on a schedule, compared with putting it all in on day one.
Steady buyingAll on day oneMoney put in
Leverage
Leveraged ETF calculator
What a fund that resets its leverage every day would have returned, next to the coin itself.
Daily-reset fundThe coin itselfSimply 2x the return
Reality check
Price target
What a target price would mean for a coin's market cap.
Converter
Convert
Any coin to dollars or to another coin, at live prices.
Head to head
Compare coins
Side-by-side price, size, supply and performance.
Market cap comparison
What if
The price a coin would have with another coin's market cap.
Flippening watch
Closest races
Neighbours nearest to swapping rank (stablecoins excluded).
Dominance
Market share
Share of total crypto market cap.
Profit & loss
Return check
What a past buy is worth at today's price.
Risk
Position size
How much to buy so a stop-out loses only what you choose.
A stop-loss isn't guaranteed. Gaps and slippage can fill past your stop and make the loss bigger.
Supply
Dilution check
Circulating vs. maximum supply, and the cap if every coin existed.
Investing
Average cost
Your weighted average price across several buys.
Investing
Break-even
The selling price that gets your money back after fees.
Risk
Comeback
The gain needed to recover from a drop.
Start
After drop
Investing
Rebalancer
Trades needed to get back to your target mix.
Coin
Now
Target %
Trade
Today's crypto prices by market cap
How does a blockchain work?
A blockchain is a shared record of transactions, grouped into blocks and linked in order. Each block points to the one before it, so changing the past means redoing everything after it.
From payment to block
Each block records the hash of the one before it. Editing an old block changes its hash and breaks the chain from that point on. Free to reuse
When you send crypto, your transaction is broadcast to the network and waits to be included in the next block. Computers on the network check that you actually own the coins and haven't already spent them.
Blocks are chained together with cryptographic fingerprints. Altering an old transaction would change its block's fingerprint and break every link after it, which the rest of the network would reject.
Networks agree on new blocks in different ways. Bitcoin uses proof of work, where miners spend computing power to add blocks. Ethereum and many others use proof of stake, where validators lock up coins as a guarantee of good behavior.
Why rewriting history is so hard
Each block includes the hash of the block before it. If someone edits a transaction in an old block, that block's hash changes, which breaks the link from the next block, and the next, all the way to today.
To get away with it, an attacker would need to redo all those blocks faster than the rest of the network adds new ones. On Bitcoin that means outspending the electricity of almost every miner in the world combined; on proof-of-stake chains it means controlling a huge share of all staked coins, which the network can then penalize.
Blocks, fees and waiting times
Blocks have limited room, so transactions compete for space. When the network is busy, users offer higher fees to get in sooner, which is why fees rise during market rushes.
Different chains make different trade-offs. Bitcoin adds a block about every 10 minutes and favors security and simplicity. Ethereum adds one every 12 seconds. Some newer chains are faster still, usually by relying on fewer, more powerful validators.
What a hash actually looks like
Changing 10 to 11 produces a completely different SHA-256 hash, with 60 of 64 characters different. That is why an edited block can't keep its old fingerprint. Free to reuse
Bitcoin uses a hash function called SHA-256. You feed it any data, a word or a whole block of transactions, and it returns a 64-character string of digits and letters a to f. The same input always gives the same output, and there is no practical way to work backward from the output to the input.
Here is a real example you can repeat with any SHA-256 tool online. The text "Alice pays Bob 10 BTC" hashes to a string beginning 6442586992b50a27. Change the 10 to 11 and the hash begins d4bb3b3c3f89642a instead. Of the 64 characters, 60 are different. There is no pattern linking the two, so you can't nudge an input to land on a hash you want.
Blockchains use this property twice. Each block's header includes the hash of the previous block, which is what chains them together. On Bitcoin, mining is also a hash puzzle. Miners change a number in the block header, called the nonce, over and over until the block's hash falls below a target set by the network. Finding one takes enormous trial and error, but anyone can check a winning answer with a single hash, which is why nodes can verify blocks so cheaply.
How long settlement really takes
Six Bitcoin confirmations take about an hour on average. Ethereum finalizes after two epochs, roughly 12.8 minutes, after which reversal would require destroying a large amount of staked ETH. Free to reuse
"Confirmed" means different things on different chains. On Bitcoin, a block arrives about every 10 minutes on average, though any single gap can be 1 minute or 40. Each extra block on top of yours makes reversal harder. Six confirmations, about an hour, is a common rule of thumb that many exchanges have used for deposits, while small payments are often treated as settled after one.
Ethereum works in fixed time slots of 12 seconds, grouped into epochs of 32 slots, or 6.4 minutes. A transaction is considered finalized once two epochs have passed, roughly 12.8 minutes after it's included. After that point, undoing it would require validators holding at least a third of all staked ETH to break the rules, and the protocol would destroy their stake as a penalty.
These numbers matter in practice. If an exchange says your deposit is waiting for 3 of 6 confirmations, you can expect about 30 more minutes on Bitcoin. A block explorer shows the live count for any transaction, so you can check progress yourself rather than refresh the exchange page. Faster chains often settle in seconds, but usually by trusting a smaller set of validators.
Key terms
Hash
A short fingerprint of data. Change one character and the hash changes completely.
Proof of work
Miners compete to solve a puzzle that costs electricity to win the right to add a block.
Proof of stake
Validators put up coins as a deposit and are chosen to add blocks.
Finality
The point after which a transaction is practically impossible to reverse.
A secure ledger can still hold a risky coin
Whether the coin is worth anything. A secure chain can carry a worthless token.
Whether apps on it are safe. The chain can be sound while a smart contract built on it has a bug.
How decentralized it really is. Some chains rely on a small number of validators or mining pools.
What people get wrong
A blockchain doesn't store files or photos for most coins. It stores small records of transactions and balances.
Transactions aren't instant everywhere. On Bitcoin, a new block arrives about every 10 minutes, and large payments often wait for several.
Why it matters
How a network agrees on blocks shapes how secure it is, how fast it settles and how new coins are issued.
Common questions
What is a block?
A batch of recent transactions, plus a reference to the previous block. On Bitcoin each block also creates new coins as a reward.
How do blockchain confirmations work?
Each new block added after the one holding your transaction counts as a confirmation. More confirmations make it harder to reverse.
Who decides which transactions go into a block?
The miner or validator building that block. Most pick the transactions paying the highest fee per unit of block space, since they keep the fees. That's why a low-fee transaction can sit waiting in the mempool for hours when the network is busy, then clear once demand falls.
