bech32

Bech32 is an encoding scheme designed for human readability and error detection, and it is used to encode Segregated Witness (SegWit) addresses in Bitcoin. It was defined in Bitcoin Improvement Proposal 173 (BIP-173) and published in 2017. A Bech32 string consists of a human-readable part, a separator, a data portion, and a six-character checksum. The human-readable part identifies the network (for example, "bc" for Bitcoin mainnet and "tb" for testnet); the separator is the numeral "1"; the data part is encoded using a 32-character alphabet.

The data portion is formed by converting the underlying binary data into 5-bit words and appending a checksum computed via a polymod-based algorithm. The checksum provides robust error detection for common transcription and typing errors. Bech32 strings are typically emitted in lowercase to avoid confusion from mixed case, although the standard itself is designed to be case-insensitive.

Bech32 addresses commonly begin with "bc1" on Bitcoin mainnet or "tb1" on testnet, followed by the data payload. Compared with earlier address formats, Bech32 offers improved error detection and a compact representation for short witness programs, such as P2WPKH and P2WSH. In addition to Bech32, a related variant called Bech32m was introduced in BIP-350 for Pay-to-Taproot (P2TR) addresses, using a different checksum constant to address potential edge cases. The Bech32 encoding has a practical maximum length of 90 characters.

Bech32’s adoption in wallets and software has contributed to more reliable address handling, with Bech32m used specifically for Taproot-related addresses.