Amounts & fees
Invoice amounts and fees: calculate before sending
Distinguish a deducted fee from a fee charged on top.
1Start with the cryptocurrency amount due
On the current valid invoice, locate the payment asset and quantity due. A product priced at 25 dollars does not necessarily require 25 USDT: checkout conversion, market prices or additional charges can affect the invoice. Use its stated cryptocurrency quantity. If it requests 0.0004 BTC, compare BTC quantities rather than entering “25 dollars’ worth” in your wallet. The 25 USDT and 1 USDT amounts below only explain the arithmetic; they are not current exchange or merchant quotes.
2Identify entered amount, fee and received amount
A sending screen may show an entered amount, a fee and an expected received amount. They need not be equal. The important comparison is between expected receipt and the invoice amount, not simply the number in the input field. Establish how fees are charged before choosing a formula. If a field only says “amount,” inspect the final preview for the total debit and expected receipt instead of guessing. The two formulas here apply only to a fixed fee charged in the same asset as the payment.
3When the fee is deducted from your entry
Arithmetic example: the invoice needs 25 USDT and a fixed 1 USDT fee is deducted from the amount entered. Entering 25 would deliver an expected 24. Entering 26 would leave an expected 25 after the fee. Formula: entered amount = required receipt + fixed fee. The total debit in this example is 26 USDT. Confirm that the preview actually shows 25 USDT received. Additional charges, precision limits or another fee convention require a fresh calculation.
4When the fee is charged on top
With the same 25 USDT required receipt and 1 USDT fee, a fee charged on top means entering 25 and paying another 1. Your available balance must cover 26 USDT. Entering 26 in the send field could deliver 26 instead. Formula: entered amount = required receipt; total debit = entered amount + fixed fee. Both conventions have the same total cost in this example, but require different entries. Use the actual preview rather than the platform name or a previous withdrawal to identify the convention.
5What if the fee is a percentage?
Establish which amount the percentage applies to and whether it is deducted or charged on top. This site’s calculator handles fixed fees in the payment asset, not percentage fees. It accepts a fixed token quantity for the fee; entering 1 for a 1% fee would incorrectly treat it as one token. Arithmetic example: the invoice needs 99 USDT and the sender deducts 1% of the entered amount. Enter 100, pay a fee of 1 and deliver 99. Simply adding 1% to 99 gives an entry of 99.99, which leaves only 98.9901 after the deduction. The formula is: entered amount = required receipt ÷ (1 − fee rate). If the 1% is instead charged on top of the sending amount, enter 99; the extra fee is 0.99 and the total debit is 99.99. These are hypothetical rules, not Binance, OKX or card quotes. Minimum fees, combined fixed/percentage charges, caps and decimal limits require the provider’s actual received-amount preview.
6Keep wallet gas separate when it uses another asset
If a wallet sends 25 USDT and separately requires an ETH network fee, budget those two assets separately. Do not add the ETH quantity to the USDT quantity and send more USDT. Gas costs can also change with network conditions. Check the fee asset shown in your wallet preview; some wallets provide alternative-token fee payment. Our calculator handles a fixed fee in the same asset. It neither converts ETH or TRX to USDT nor estimates the gas for your next personal-wallet transaction.
7Also check withdrawal minimums and precision
A reasonable fee does not ensure a small payment can be withdrawn. If an invoice needs 3 USDT but the route disallows such a small withdrawal, reducing the fee will not solve that constraint. An exchange withdrawal minimum is also different from a merchant’s minimum purchase. Check which quantity the minimum applies to and how many decimal places the receiving amount can use. If the preview cannot match the invoice, use another merchant-supported method or follow its instructions instead of deliberately overpaying. The minimums and withdrawal status shown here help with comparison; confirm them in your own account. Suppose the invoice needs 3 USDT but the current withdrawal minimum is 5. Sending 5 to the merchant would overpay; splitting the withdrawal would not solve the sender’s minimum. If the merchant supports personal-wallet payments, assess funding your own wallet first and then paying the exact amount, including both fees and the balance left in that wallet. Another payment method already offered by the merchant may also work. These numbers explain the constraint; they are not current platform data.
8Exchange to wallet to merchant involves two transfers
When payment requires a personal wallet, account for two transfers: the exchange-to-wallet withdrawal and the wallet-to-merchant network transaction. Purchase spreads, trading fees and conversion costs are also outside a single withdrawal fee. Do not combine charges in different assets into one token quantity. The calculator can show Binance and OKX withdrawal-fee data with an update time. It helps compare fixed withdrawal fees and do the arithmetic. Your account conditions, sending method or later platform changes may produce different results. Recheck the withdrawal preview when data is expired or unavailable.
9For underpayment or expiry, do not pay again immediately
If expected receipt is too low and you have not submitted, go back and correct it, then check the invoice is still valid. If you already sent, keep the order reference, transaction ID and amount, and read the merchant’s current instructions. An underpayment may not accept a top-up, and an overpayment may not be refunded automatically. If an invoice expires after you sent funds, do not immediately create and pay a replacement. Check the original order through the merchant’s official website or support; do not assume a second transfer will be combined with the first.
10Common questions: buffers, maximum send and changing fees
Is sending a little extra safer? No. Keep enough balance to cover fees, but deliver the quantity the invoice requires. Can I press “send all”? Inspect the preview first. A maximum-send function generally works from your available balance and fee rules; it does not match the merchant invoice for you. Why does my account show a different fee? Compare the asset, network, update time and applicable charging conditions, then use the current confirmation screen. Before confirming, check expected receipt against the invoice and ensure your balance covers fees, the network matches and the invoice has not expired.
Sources
Based on the merchant’s official instructions. We have not tested every payment ourselves; check your own invoice before paying.
BitPay · Underpaid or overpaid invoices ↗Binance · Withdrawal fee and minimum fields ↗OKX · Currency withdrawal information ↗Ethereum · Gas and fees ↗MetaMask · Sending tokens ↗