Paying with crypto directly is still rare. Paying with a card funded by crypto works everywhere. The bridge between the two is a deposit: you send coins, a provider converts them to dollars, and the dollars fund a card. This article explains what happens in that conversion, which coins make sense, and what the fees really are.
What "funding a card with crypto" means
Nobody spends Bitcoin at a checkout that only takes Visa. What happens instead is that you send crypto to a payment address, a processor converts it to dollars at that moment's rate, and the dollars land in a wallet from which the card is loaded. From the merchant's side it is an ordinary card payment in dollars. The crypto part is finished before you ever create the card.
Which coin to send
Stablecoins: USDT and USDC
The natural choice. One USDT is one dollar, so what you send is what you get, minus fees. No rate to worry about between pressing send and the payment confirming. Both exist on several networks, and the network decides the transfer fee and speed.
Bitcoin
Works, but Bitcoin's price moves while your transaction confirms, which can take ten minutes to an hour. Most processors lock the rate for a short window, so if the confirmation arrives late, the amount credited may differ slightly from what was quoted. Network fees are also higher when the chain is busy. Fine for larger deposits, wasteful for a $20 top-up.
TRON (TRX), Ethereum (ETH), Litecoin and others
Accepted by most processors. The same caveats as Bitcoin apply to any volatile coin: the rate is only fixed for a window, and a late confirmation can shift the amount. Litecoin and TRX are cheap to send and confirm fast, which makes them reasonable alternatives to stablecoins if you already hold them.
Networks, not just coins
USDT on Tron, USDT on Ethereum and USDT on Solana are the same dollar-pegged token on different rails. The provider's payment page shows an address for one specific network. Send on that network only. Coins sent on a different network to that address are lost, and no provider can recover them. Typical costs per transfer at the time of writing: Tron under a cent to a few cents, Solana a fraction of a cent, Ethereum anywhere from a dollar to ten or more depending on congestion.
The real fee stack
- Exchange withdrawal fee. Charged by wherever the coins are coming from. Often a fixed amount per withdrawal. Check whether it is deducted from what you typed or added on top.
- Network fee. Paid to the blockchain. Depends on the network, not the provider.
- Deposit fee. Charged by the card provider for accepting and converting crypto. Usually a percentage, sometimes plus a fixed amount. It should be shown before you send.
- Rate. For volatile coins, the conversion rate at the moment of the deposit. For stablecoins, effectively one to one.
For a $100 top-up with USDT on Tron from a typical exchange: a one-dollar withdrawal fee, a few cents on the network, and the provider's deposit fee. For the same amount in Bitcoin the network fee alone can be several dollars, plus rate movement.
Timing and partial payments
Payment pages quote an exact coin amount for a limited time. Two things go wrong at the edges. If the exchange deducts its fee from the amount, less arrives than quoted, and the deposit is credited as partial. If the transfer confirms after the window, the rate may have moved. Both are avoided by sending the exact quoted amount, promptly, from a wallet where you control the fee. Reputable providers credit whatever arrives rather than losing it, but a partial payment will not complete an order that needed the full amount.
Sending from an exchange versus a wallet
An exchange is convenient and often has a fixed withdrawal fee. A self-custody wallet lets you set the network fee and send the exact amount. Either works. What matters is that you read the exact amount and network from the payment page, and that you do not send from a wallet that adds its own fee on top of the amount you type.
Once the dollars land
From here it is card business, not crypto business. The balance stays in dollars, cards draw from it, unspent balance from closed cards comes back to it, and you top up again when it runs low. There is no reason to keep converting back and forth.