Enter exactly 128 or 256 entropy bits, compute the BIP-39 checksum locally, and map the result to the official English mnemonic word list.
Offline use recommended: download this HTML file and open it on a computer disconnected from the internet. This page has no external libraries, network requests, analytics, storage, cookies, or server component.
Test data warning: never use generated test seeds or example seeds for real bitcoin.
128-Bit Entropy Grid
Columns are faces 0 through 7. Rows are bit positions 1 through 16. The selected face order is read one full column at a time, top to bottom.