Your BIP39 seed (12 or 24 words) is the only thing standing between you and your wallet funds. If you lost it partially — you remember 10, missing 2; or you misread the paper and doubt 3 — the key question is: is it mathematically recoverable?
This guide answers with numbers. No marketing.
How BIP39 works (short version)
BIP39 is the Bitcoin Improvement Proposal #39 standard. It converts a random sequence of bits (entropy) into human-readable words from a fixed 2048-word dictionary (English, Spanish, Japanese, Italian, etc).
- 12 words = 128 bits entropy + 4 bits checksum
- 24 words = 256 bits entropy + 8 bits checksum
- Each word represents 11 bits (2^11 = 2048 = dictionary size)
- Last block always includes a SHA-256 checksum derived from the rest
The checksum is the magic: tells you if a proposed seed is mathematically valid (15/16 random proposals fail checksum). That reduces search space 16x when only the last word is missing.
Concrete table: how many words can you lose
| Missing words | Search space | Time on our cluster | Viable? |
|---|---|---|---|
| 1 word (any position) | 2048 candidates × 24 paths | < 1 minute | ✓ Trivial |
| 2 words (any position) | 4M × 24 paths = 96M | 5-30 minutes | ✓ Trivial |
| 3 words | 8 billion × 24 paths | 1-3 days | ✓ Viable |
| 4 words | 17 trillion × 24 paths | 5-21 days with LSTM hints | ⚠️ Edge |
| 5 words | 35 trillion × 24 paths | ~years | ✗ Impossible |
| 6+ words | 72 quadrillion+ | impossible in lifetime | ✗ Forget it |
The "× 24 paths" refers to standard BIP44/BIP49/BIP84 derivation paths (legacy, segwit, taproot, etc) — Bitcoin Core, Electrum, Trezor, Ledger use different paths. Our engine tries them all to find which one your wallet used.
The hint boost
Three types of information that reduce search:
1. You know exact POSITION of missing words
If you remember "I'm missing words 5 and 17", you reduce position space. Without knowing, we'd have to try 12!/2! position pairs × 2048² candidates. Knowing positions eliminates that factor.
2. You remember INITIAL letter or approximate LENGTH
BIP39 words are 3-8 letters. If you remember "I think it started with S", you reduce from 2048 to ~100 candidates per word (the 100 starting with S in wordlist).
3. You know wordlist language
Official BIP39 supports 10 languages. If your wallet was created in MetaMask with EN UI, almost certainly EN wordlist. Mycelium in Spanish = ES. Confusing wordlists is cause #1 of "my seed doesn't work" (words exist but SHA-256 checksum fails).
When we CAN'T do anything
5+ missing words: 2048^5 = 36 trillion × 24 paths = 864 trillion attempts. Our cluster at 100M ops/sec needs 274 years. If someone says "guaranteed recovery of 6 missing words", it's a scam.
Without knowing wordlist language: multiply everything by 10. What was viable becomes marginal.
Without idea of derivation path + non-standard wallet (Cardano, Solana, etc): we may finish the AI Scan successfully but without knowing which addresses to check for validation.
Real case (anonymized)
Client inherited a Trezor. The seed paper was partially burned — legible 10/12 words + partial of 2 missing ("c..." and "...mar"). Said wallet should have ~2 BTC from 2017.
- Phase 1 — Diagnostic USD 35: confirmed derivation path BIP44 (Trezor standard wallet). Verified the 10 read words existed in EN wordlist. Positions 4 and 9 of missing confirmed. Viable estimate.
- Phase 2 — AI Scan USD 2,000: LSTM engine generated 156 candidates for "c..." (BIP39 EN words starting with C: cabin, cabbage, café...) × 89 candidates for "...mar" (words ending in mar: hamster, harbor, etc). 13,884 combinations. Tested all against UTXO balance on GPU cluster. Found in 4 hours:
cattle(pos 4) +summer(pos 9, actually ended in "mer" not "mar" — our fuzzy expansion caught it). - Phase 3 — Recovery: client imported seed in Electrum, transferred 1.97 BTC (~USD 110,000 at moment exchange) to new wallet.
- Success fee: 30% × USD 110,000 = USD 33,000. Client kept USD 75,000 net vs USD 0 without us.
What to do if your case is "viable"
- Make an honest inventory: how many words missing, which positions, what hints (initial, language, approximate length)
- DO NOT import partial seed in any online wallet — some save locally what you input and are hack vectors
- Find original device (Trezor/Ledger): has metadata of derivation path
- Check blockchain explorer with any address you remember — confirms wallet has funds
- Pay USD 35 Diagnostic: we tell you in 24h if your case is "viable" or "impossible". Honest.
To start, the Wallet Recovery page has all details. And if you have 5+ missing words, don't spend money on any service — mathematically irrecoverable, no matter who tells you otherwise.