The first time someone moves crypto between wallets, two things usually surprise them. The fee, which can be larger than expected and bears no relation to the amount being sent. And the network dropdown, which asks a question they did not know existed and which, answered wrongly, loses the funds.
Both come from the same place: a blockchain is a shared resource with limited capacity, and fees are how that capacity gets allocated.
Why a fee exists at all
A blockchain processes transactions in blocks, and each block holds a limited amount of work. Far more transactions want in than fit, so something has to decide the order. That something is price: users attach a fee, and whoever assembles the block generally takes the most valuable transactions first.
This has two consequences that explain most of what people find confusing. The fee is not a percentage of what you send, because the network does not care about the value — moving a million dollars and moving five dollars consume identical block space. And the fee is not fixed, because it is set by an auction against everyone else transacting at that moment.
The term "gas" comes from Ethereum, where each operation has a cost measured in gas units. A simple transfer costs 21,000 gas; a complex smart-contract interaction costs far more. What you pay is gas used multiplied by the gas price, and the gas price is the part that moves with demand.
Why the same action costs wildly different amounts
Networks make different design trade-offs, and fees are where those trade-offs surface.
Ethereum prioritises decentralisation and security, with block space deliberately constrained so that ordinary hardware can run a node and verify the chain. Constrained supply against high demand produces high prices. Fees range from around a dollar in quiet periods to tens of dollars during congestion, and a complex interaction during a busy moment can cost more than that.
Layer-2 networks — Arbitrum, Optimism, Base, zkSync and others — execute transactions off the Ethereum main chain, batch them, and post compressed proofs or data back to it. The cost of Ethereum's security is shared across thousands of transactions instead of borne by each one, which typically brings fees to a cent or below while retaining a meaningful security relationship with Ethereum.
Alternative layer-1 chains — Solana, Avalanche, and others — make different choices about block size, validator hardware requirements and consensus, generally achieving higher throughput and much lower fees, with correspondingly different decentralisation and reliability characteristics.
Bitcoin has small blocks and a ten-minute target, and fees rise sharply when the mempool backs up. It is not designed for cheap frequent transfers.
None of these is simply better. They price different things, and the right choice depends on what you are doing.
Fees move, sometimes a lot
Gas prices follow demand, and demand is spiky. A popular token launch, a large liquidation cascade, or an NFT mint can multiply fees within minutes. Fees are also broadly cyclical through the day, tending to be lowest during the quietest hours for the network's dominant user base.
If a transaction is not urgent, waiting is free and often saves most of the cost. Fee trackers for the major networks show current levels and recent history, and the difference between a busy Tuesday afternoon and a quiet Sunday morning is frequently a factor of five or more.
Most wallets offer a speed choice — slow, standard, fast — which simply sets your bid. A slower setting risks the transaction sitting pending until the market clears, but on most networks it will eventually confirm rather than fail.
The network dropdown, and the loss it causes
Here is the part that costs people real money.
The same asset frequently exists on multiple networks as separate tokens with the same name. USDT exists on Ethereum, Tron, Solana, Avalanche and others. USDC likewise. They are not interchangeable. USDT on Tron cannot be received by an Ethereum address, even though the ticker is identical and the balance looks the same in an interface.
Send tokens over a network the receiving wallet or exchange does not support and they are usually gone. Sometimes an exchange can recover them manually, as a discretionary favour, slowly, occasionally for a fee. Often it cannot, and the tokens sit at an address nobody can reach.
The countermeasures are simple and worth making habitual. Before sending, confirm which network the receiving address expects — the deposit screen states it explicitly, and if it does not, do not send. Confirm that the sending side is set to the same network. Send a small test amount first, wait for it to arrive, then send the rest; on a cheap network this costs a cent, and on an expensive one it still costs far less than the alternative.
Be particularly careful with addresses that look valid on more than one chain. Ethereum-style addresses are used by many networks, so a well-formed address gives no indication of which chain it belongs to. Validity is not confirmation.
Fees you also need to hold
A transaction fee is paid in the network's native asset, not in the token being moved. Sending USDT on Ethereum requires ETH in the same wallet. Sending a token on Solana requires SOL. Sending on BNB Chain requires BNB.
This catches people constantly: a wallet holds $500 of a token, no native asset, and the tokens cannot be moved at all until some is sent in. Keep a small balance of the native asset in any wallet holding tokens on that chain.
Failed transactions still consume fees. If a transaction runs out of gas or reverts, the work done up to that point was still performed and is still charged. The tokens are not lost, but the fee is.
Choosing a network in practice
For small transfers you make often, use a layer-2 or a low-fee chain, where fees are negligible.
For large transfers where security matters most and the fee is trivial as a proportion, Ethereum's main chain remains the conservative choice — a $20 fee on a $200,000 transfer is a rounding error and buys the most battle-tested settlement layer available.
For moving between exchanges, check what both ends support and pick the cheapest common network. Withdrawal fees vary substantially by network on the same exchange, and choosing well can save more than the trade cost.
For interacting with a specific application, you have no choice: use the network it deploys on.
Bridging between networks
Moving an asset from one chain to another requires a bridge, which typically locks the asset on the source chain and issues a representation on the destination.
Bridges have been among the most heavily exploited components in crypto, with several individual incidents exceeding $100 million, because they concentrate large balances in complex contracts. If you must bridge, prefer well-established bridges with long operating histories, or route through a centralised exchange instead — deposit on one network, withdraw on another, which uses the exchange's own internal transfer rather than a bridge contract. It is often cheaper and, for most people, safer.
A short checklist
Before any transfer: does the receiving side support this exact network? Is the sending side set to that network? Do you hold enough of the native asset to pay the fee? Have you verified the full address rather than the first and last characters? And for anything substantial, have you sent a test amount first?
Five questions, under a minute, and they eliminate the most common way people permanently lose crypto.
This article is educational and is not financial, investment or tax advice. Coinvilo does not hold funds or process transfers; swaps on this site are executed non-custodially by a third-party exchange partner.