USDT vs USDC: Which Stablecoin Should You Use to Top Up Your Card?

If you're topping up a crypto card, you'll almost always be choosing between USDT (Tether) and USDC (Circle) — the two largest stablecoins by far. Both aim to stay worth $1. Here's where they actually differ. ## They're both pegged to the dollar — that part's the same Neither is meant to be volatile like Bitcoin or Ethereum. Day to day, $100 of USDT and $100 of USDC should both be worth close to $100. For the purpose of topping up a spending card, this is the whole point: predictability. ## Where they differ: issuer and transparency USDC is issued by Circle, a US-regulated company that publishes regular attestations of its dollar reserves. USDT is issued by Tether, which has a longer track record and by far the larger market cap and liquidity, but has historically faced more scrutiny over reserve transparency. Neither difference affects how the coin behaves when you're using it to top up a card — both settle instantly and both are widely supported — but it's worth knowing if you're holding either for longer than the time it takes to top up. ## Network matters more than the coin itself Both USDT and USDC exist on multiple blockchain networks — commonly Ethereum (ERC20), Tron (TRC20), and others. This is actually the detail that affects your experience most: - TRC20 transfers are typically fast and very cheap (fractions of a cent to a few cents in network fees). - ERC20 transfers can cost significantly more in gas fees, especially when Ethereum is busy. When you're topping up a card, check which network your CasperCard wallet address is for before sending — sending the right coin on the wrong network, or vice versa, is one of the most common (and avoidable) mistakes in crypto. ## Which should you actually use? For topping up a spending card, TRC20 USDT is usually the cheapest and fastest combination for most people, simply because Tron network fees are so low. If you already hold USDC for other reasons, it works just as well — just double-check you're sending on a network your card supports. CasperCard supports both USDT and USDC, along with other major coins, across multiple networks — check your dashboard for the exact addresses and current fee for each.