What the parts mean
The prefix tells the network and the amount: lnbc is Bitcoin mainnet, lntb testnet, lntbs signet, lnbcrt regtest. Digits after it with a multiplier give the amount: m = milli-bitcoin, u = micro-bitcoin, n = nano-bitcoin, p = pico-bitcoin. So lnbc2500u is 2,500 µBTC = 250,000 sats. An invoice with no digits leaves the amount to the payer.
After the bech32 separator "1" come a timestamp and tagged fields: p (payment hash), s (payment secret), d (description) or h (its hash), x (expiry in seconds, 3,600 by default), c (minimum final CLTV delta, 18 by default), n (payee node), f (on-chain fallback address), r (private route hints) and 9 (feature bits). The last 65 bytes are the signature.
amount: lnbc + number + multiplier m = 0.001 BTC · u = 0.000001 BTC · n = 10⁻⁹ BTC · p = 10⁻¹² BTC
expires at = timestamp + x (default 3,600 s)Typical checks before paying
- The amount matches what you agreed to pay.
- The invoice has not expired — expired invoices cannot be paid, ask for a new one.
- The description fits the purchase. A description hash (h) instead of text is normal for LNURL payments.
- Each invoice is for one payment. Paying the same invoice twice is not possible once it is settled.
Limitations
The decoder checks the bech32 checksum and parses the fields, but it does not verify the signature, so the payee node shown is what the invoice claims. Your Lightning wallet verifies the signature when paying. BOLT12 offers (strings starting with lno) use a different format and are not decoded here.
Frequently asked questions
+How long is a Lightning invoice valid?
Until timestamp + expiry. The default expiry is one hour (3,600 seconds) unless the invoice sets the x field.
+What does lnbc1… without an amount mean?
An invoice with no amount: the payer chooses how much to send, for example for donations.
+Can I send on-chain bitcoin to a Lightning invoice?
Not directly. Only if the invoice includes an on-chain fallback address (f field) — and then you are paying that address, not the invoice.
+Is the payment hash secret?
No. The payment hash is public; the preimage that the payee reveals on payment is the proof of payment.
+Does KOT.CASH accept Lightning invoices?
No. Swaps use on-chain Bitcoin addresses for deposits and payouts.
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