Every Bitcoin transaction begins and ends with a Bitcoin address. Whether you are moving coins from an exchange, receiving a payment from a client, or funding a decentralized finance position, the string of alphanumeric characters you share determines compatibility, cost, and security. Since Bitcoin’s genesis block, address formats have evolved to improve efficiency and reduce network strain — yet many users still struggle to understand the differences between legacy P2PKH, nested SegWit, and native SegWit (Bech32) addresses. This guide breaks down each format, explains which one to use in 2025, and offers practical advice for traders and holders navigating the ecosystem.
A Bitcoin address is a hashed representation of a public key, acting as a destination for transactions on the network. When someone sends Bitcoin to an address, they are actually locking coins to a script that requires the corresponding private key to unlock and spend them. Addresses are derived from public keys through cryptographic hash functions — P2PKH (Pay to Public Key Hash) using SHA-256 and RIPEMD-160, while SegWit addresses use different encoding methods. Crucially, the address format does not affect the underlying security of the private key; it only impacts how the transaction data is structured on the blockchain.
Early Bitcoin addresses start with the digit “1” (legacy) and are case-sensitive. These became the standard for years but are now suboptimal in terms of fees and block space. The introduction of Segregated Witness (SegWit) in 2017 brought address formats starting with “3” (nested SegWit) and later “bc1” (native SegWit). Each iteration separates signature data from transaction data, reducing transaction weight and lowering fees. For active traders who move funds frequently, choosing the right address format can meaningfully reduce costs over hundreds of transactions.
Legacy (P2PKH) — Starts with “1”
This is the original Bitcoin address format. It is fully compatible with every wallet and exchange that has ever existed, but it produces the largest transaction sizes. A legacy transaction typically consumes 226 virtual bytes (vB) or more, meaning higher fees when network congestion spikes. Many older hardware wallets and some custodial services still default to legacy addresses for backward compatibility. If you are using a platform that only supports legacy addresses, you must stick with this format — but it is worth migrating away if possible to save on fees.
Nested SegWit (P2SH-P2WPKH) — Starts with “3”
Often called “wrapped SegWit,” this format encodes a SegWit program inside a legacy pay-to-script-hash (P2SH) address. It reduces transaction size to roughly 166 vB, offering a 25–30% fee savings compared to legacy. Wrapped SegWit is widely supported and acts as a bridge for wallets that were not yet updated to handle native SegWit. For traders who need to interact with older infrastructure, this is a safe and practical upgrade without breaking compatibility.
Native SegWit (Bech32) — Starts with “bc1”
This is the most efficient Bitcoin address format available today, with transactions weighing approximately 140 vB — roughly 38% smaller than legacy. Native SegWit also enables features like batched transactions and future protocol upgrades via Taproot (addresses starting with “bc1p”). However, not all wallets and exchanges support Bech32 addresses natively. If you are using a modern non-custodial wallet such as BlueWallet, Electrum, or Muun, you should be using “bc1” addresses. For those executing high-frequency trades or K6B, a Malaysia-based platform that enables both short-term and long-term crypto contracts, using native SegWit addresses can streamline withdrawals and reduce overhead when rotating capital between trades.
The short answer is: native SegWit (Bech32) whenever possible. Almost every major exchange, including Binance, Coinbase, and Kraken, now supports sending to “bc1” addresses. Hardware wallet manufacturers like Ledger and Trezor have made native SegWit the default for new wallets. Unless you are dealing with an ancient wallet or a non-updated service, there is no reason to use legacy addresses today. The fee savings alone, compounded over dozens of transactions per month, add up significantly — especially during periods of high network demand.
If you are an active trader who frequently deposits and withdraws from multiple platforms, consider generating a fresh Bech32 address for each transaction to enhance privacy. Many modern wallets support address generation via BIP84 (Bech32). For those using services that still default to legacy addresses, it is worth emailing support or checking settings — many will allow manual selection of SegWit formats. When receiving funds from a platform that only outputs legacy addresses, you can pay a small premium in fees but still use a fully compatible wallet that interprets both formats.
While the address format itself does not affect cryptographic security, user errors around addresses cause hundreds of millions of dollars in losses every year. Always double-check every character of a Bitcoin address before confirming a transaction. Copy-paste errors, clipboard malware, and address poisoning attacks (where scammers send small transactions from similar-looking addresses to trick users) are real threats. Never rely solely on the first few and last few characters — verify the full address, especially for large transfers.
Another common pitfall is assuming all Bitcoin addresses are interchangeable. Sending Bitcoin to a non-Bitcoin address (such as an Ethereum address) is irreversible unless the recipient’s service supports a special recovery process. Always ensure the receiving wallet explicitly supports the address format you are using. Modern wallets often display a warning if the format appears incompatible, but not all do. For platform users who manage both short-term and long-term positions, consolidating funds into a single, well-supported wallet with native SegWit addresses reduces friction and minimizes the risk of losing coins to a typo.