Economics

OP_RETURN Baseline

Standard OP_RETURN script is ≤ 83 bytes total, allowing ≤ 80 bytes data. All bytes are non-witness, costing 1 vbyte per byte. For 80 bytes of data you typically consume ˜91 vbytes including script overhead and output framing.

P2WDA Spend

The witness bytes calculation for a P2WDA input includes:

• 1 byte for item count.
• 10 bytes for length prefixes (one per data slot).
• The actual compressed data bytes.
• ˜73 bytes for the transaction signature (including length prefix).
• ˜41 bytes for the witness script (including length prefix).

Since all of this is witness data, it costs only 1/4 the weight of equivalent non-witness bytes.

Example with 512 bytes of incompressible data:

• Data + signature = 576 bytes total.
• Split across 8 slots (72 bytes each).
• Total witness bytes ≈ 701.
• Cost in vbytes ≈ 175.

Compare to OP_RETURN which would need 7 outputs at ˜91 vbytes each ≈ 637 vbytes. Result: ˜72% savings while keeping everything in a single transaction.