What a quote is
When a price is denominated in a fiat currency but settled in crypto, two numbers are involved: the fiat amount, which is what the merchant actually charges, and the crypto amount, which is what the customer sends. The bridge between them is the conversion rate. A quote is the result of running that conversion once, at a chosen instant — the fiat price multiplied by the rate observed at that moment, expressed as a concrete amount of a specific asset on a specific chain.
The defining property of a quote is that it is a fixed figure, not a live calculation. A merchant who priced something at one hundred units of fiat does not ask the customer to pay whatever that converts to at the moment their transaction lands; they ask for the exact crypto amount the quote names. That number stays constant while it is valid, even as the underlying market rate keeps moving. This is what lets a customer be shown a single amount to pay and a single address to pay it to.
A quote is meaningful only for a bounded window. The rate it was computed from is a snapshot, and the longer it is held the further the real market can drift from it, so a quote is paired with an expiry. Inside the window the quoted amount stands; once the window passes, the quote is stale and any remaining payment has to be re-quoted at a fresh rate. The quote governs the conversion math only — it fixes how much crypto equals the fiat price, not how the network behaves once that crypto is sent.
What it means in a crypto payment
For a merchant, the quote is what turns a fiat-priced sale into something a customer can pay in crypto with no ambiguity. The customer sees one amount, sends exactly that, and the payment is judged against the quoted figure rather than against whatever the rate happens to be when the deposit confirms. It is also the reference point for whether a payment is complete: a deposit that matches the quote settles the charge, a deposit below it is short, and a deposit above it is in excess — all measured against the quoted amount.
The quote and its expiry work as one guarantee. A customer who pays within the window pays the amount they were quoted; a customer who waits past it finds the quote no longer valid and is re-priced, because the rate behind it can no longer be safely honored. This is why a crypto payment priced in fiat carries both a fixed amount and a countdown — the amount is the quote, and the countdown is how long that quote remains binding.
Quotes on halfin
halfin invoices are fiat-anchored: the merchant sets the amount in a fiat currency, and halfin produces the quote — the exact crypto amount in the chosen asset — when the invoice is activated. From activation the invoice carries that quoted amount and an expiry by which the payment must arrive. The customer is paying a fixed figure against a deadline, and the merchant knows a deposit that lands inside the window settles the agreed fiat price.
The quote is fixed by the rate lock. The two terms describe the same moment from different angles: the rate lock is the mechanism that freezes the conversion rate at activation, and the quote is the crypto amount that freezing produces. For the rest of the invoice lifecycle the quoted amount is the yardstick — a matching deposit settles the invoice, a smaller one is treated as underpaid and a larger one as overpaid, always against the quote rather than the live market rate. If the invoice expires before payment arrives the quote lapses with it; a new invoice would capture a fresh rate and a fresh quote, and a deposit that lands after expiry is surfaced as a late deposit rather than settling at the stale figure.