Amount & quote

Transfer amounts on the public API are human-readable source crypto (the token the user is sending) for a resolved transfer plan. Fiat (currently USD) is available from rates on the balance and from getMinAmount / getQuote.

Minimum

const min = await client.wallets.transfer.getMinAmount(plan);
// min.crypto — source token units, already ceiled to display decimals
// min.fiat  — USD, ceiled to maxFiatDecimals (default 2), when rates are known

Field	Meaning
crypto	Minimum in source token units (what the user enters)
fiat?	Fiat value of that minimum when rates are known

The source min is never below the token's display-dust (getTokenMinAmount — e.g. 0.000001 ETH at 6 display decimals). A fiat amount that converts to less than that dust fails below_min. For swap/bridge, the destination min is converted into source units via exchange rates, then ceiled so typing the shown value cannot fall below the true minimum.

Validate

validateAmount does not throw. It checks flow, parse, and min.

const validation = await client.wallets.transfer.validateAmount({
  plan,
  amount, // source crypto string
});

if (!validation.ok) {
  validation.code; // 'BELOW_MIN' | 'INVALID_AMOUNT' | 'WRONG_FLOW'
  validation.message;
  validation.minAmount;
}

WRONG_FLOW is returned when plan.flow === 'unavailable'.

Recommended validation stack

1. Sanitize the input (sanitizeAmountInput / parseAmountInput) so the string is parseable (no grouping).
2. validateAmount({ plan, amount }) for flow / parse / min.
3. getQuote({ plan, amount }) when plan.flow is swap or bridge — for receive amount, fees, and ETA. Direct can skip.
4. Pass the same amount into submit. Quote is display-only.

These helpers live on @swapped/connect-sdk (same suite Coinbase uses). You do not need every helper on the wallets page — sanitize → validate → quote when needed is enough.

Crypto / fiat helpers

From @swapped/connect-sdk (same helpers Coinbase uses):

Helper	Purpose
convertCryptoToFiat({ amount, exchangeRate, decimals? })	Crypto → fiat string. decimals defaults to maxFiatDecimals (then 2)
convertCryptoToFiatCeil({ amount, exchangeRate, decimals? })	Crypto → fiat, ceiled (used for min labels)
convertFiatToCrypto({ amountFiat, exchangeRate, maxDecimals })	Fiat → crypto
validateAmountInput({ amount, minAmount, maxAmount, … })	Field validation
parseAmountInput / sanitizeAmountInput / formatAmountForInput	Input parsing

convertFiatToCrypto({
  amountFiat: '100',
  exchangeRate: 2000,
  maxDecimals: 6,
})
// "0.05"

WalletBalance.exchangeRate / fiatValue / formatted are the rate and display strings for the selected token. When min.fiat is missing, convertCryptoToFiatCeil with token.exchangeRate produces a fiat min from min.crypto.

React: useDualAmountInput keeps crypto and fiat fields in sync.

Quote

const quote = await client.wallets.transfer.getQuote({
  plan,
  amount, // human-readable source crypto
});

WalletTransferQuote:

Field	Meaning
flow	'direct' | 'swap' | 'bridge'
amountIn	{ crypto, fiat? } — what the user sends. crypto is a plain decimal (0.00000004), never scientific (4e-8)
amountOut?	{ crypto, fiat?, network, symbol } — expected receive (swap/bridge). Same plain-decimal crypto contract
networkFee?	{ amount, symbol, tokenAddress } — display fee. Swap: fiat from the route; bridge: network fee USD. symbol can be 'USD'
protocolFeeFiat?	Protocol fee in fiat when the quote exposes one
estimatedTimeSeconds?	Estimated completion time in seconds
raw?	Opaque payload from the swap/bridge quote API. Display / debug only

An invalid or empty amount throws WALLET_TRANSFER_INVALID_AMOUNT. Quote fetch failures throw WALLET_TRANSFER_QUOTE_FAILED.

submit only needs plan and amount. See Submit.