What is a Lamport?
A lamport is the minimum division of SOL: 0.000000001 SOL, or one billionth of a SOL. All balances, fees, and deposits in Solana are recorded and calculated in lamports; the nice "SOL" value shown in Phantom is just a conversion for display. The unit is named in tribute to Leslie Lamport, a computer scientist whose work on distributed systems like logical clocks, Paxos and Byzantine fault tolerance is fundamental to how any blockchain gets thousands of individual nodes to reach consensus on anything.
Consider pixels. When you look at a photo on your monitor, it appears as one seamless image; but underneath that image there exist a large number of discrete pixels and each individual edit acts upon a pixel at a time. SOL works the same way: your wallet gives you the seamless view while the network can only handle whole numbers of lamports. Fractional lamports cannot exist in this system.
Lamports Technical Function
On the Solana ledger each balance is stored as a 64-bit unsigned integer. There are no floating-point numbers at the consensus level as floating-point values have non-deterministic rounding behavior, meaning a network where two validators diverge at the 9th decimal would be an unusable network. An integer balance allows for accurate balances to each lamport.
Fees are always priced natively in lamports. There is always a base fee of 5,000 lamports per signature or $0.0004 at $80 SOL. The required amount to keep an account active follows the same unit, with a base minimum of ~890,000 lamports (0.00089 SOL), while each token account requires a minimum of 2,008,960 lamports (0.002 SOL). Priority fees go down a decimal scale by pricing lamports per compute-unit, measured in micro-lamports (millionths of a lamport), allowing for granular prioritization of smaller transactions.
Lamports versus Satoshis and Wei
Bitcoin breaks its smallest unit to 100 million (0.00000001 BTC). Ethereum, however, goes much more granular where the smallest unit is one quintillionth of ETH, or a wei (10^-18 ETH). Since balances are stored as integers there needs to be very large arithmetic (i.e. Ethereum uses 256-bit arithmetic). Solana made the decision that 1 billionth (0.000000001 SOL) would be fine since the whole SOL supply in lamports would fit in a 64-bit integer, which is native data for all modern CPUs. Every little optimization matters when you’re processing thousands of transactions per second inside of 400-millisecond slots. Most ETH users will never see their native units since they price gas in units of gwei (a billionth), the same unit as SOL.
Why Lamports Matter
If you go on a block explorer or through the Helius API you’ll only see lamports (5000 lamports in fee fields, priority fees calculated by compute-unit limit price, a deposit in lamports of 2039280 lamports for the SOL to SPL swap). Once you know that 1 lamport is 1e-9 SOL you’ll feel a bit less overwhelmed by all the numbers. Lamports also help decipher why a transaction sometimes fails. "Insufficient balance for rent" means the transfer would have put the account below the 890,000 lamport threshold, at which point the Solana node will not permit the transaction. For this reason a user may always need to keep 890,000 lamports in their wallet at all times. Lamports are also the smallest unit for staking through platforms like Marinade or Jito where you earn ~6-8% APR which accrues to amounts that will only show as an integer amount in lamports.
The only downside to the layering in Solana is the complexity. SOL as the display unit, lamports in the ledger, micro-lamports for priority fees, all for one asset, can become confusing. The problem is compounded by the fact that all wallets display amounts in SOL so most users don’t know that they paid a deposit (refundable) of lamports when they bridged assets into Jupiter.
What is the origin of the name "Lamport"?
The developers of Solana decided to honor Leslie Lamport given that his work forms an integral part of Solana's design. Proof of History, the Solana crypto-clock, builds directly upon the work of Lamport that he published in 1978 about clock synchronization in distributed systems. Satoshi was named for the creator of Bitcoin but Lamport is named for his intellectual inspiration.
