Exchange Rate Types: Mid-Market vs Cash vs Wire

Published 2026-04-13 7 min read

Summary (TL;DR)

A coworker came back from a week in Amsterdam last spring and, while reconciling card receipts, found that roughly KRW 800,000 had quietly evaporated. The cause was a series of “Pay in KRW?” prompts on restaurant terminals that he had answered “yes” to without thinking. Dynamic Currency Conversion margins of 5–7% multiplied across about KRW 12 million in card spend produce exactly that gap — and it dwarfed the actual mid-market rate movement during the same week. Most people start a conversation about FX by asking “what’s today’s mid-market rate,” but the real cost lives in the small print next to it.

Open a bank’s FX board at any Korean or international retail bank and you will see four different rates for the same currency on the same day: cash-buy, cash-sell, wire-buy, wire-sell. Above them, a single mid-market rate that you cannot actually trade at. The spread between those rates is not a mistake; it is the bank’s compensation for inventorying physical cash, processing wires, and hedging their currency exposure. The mid-market rate is the midpoint of the interbank bid and ask — the rate two banks would actually transact with each other at — and it is the only honest benchmark for “what is this currency really worth right now.” Everything a retail customer sees sits on top of it as a spread, and cash spreads are the widest because physical notes are expensive to move and vault. If you are planning travel, overseas investing, or cross-border remittance, the channel you pick — credit card with a no-FX-fee product, broker wire, specialist provider like Wise — matters more for total cost than the day’s movement in the underlying rate.

Background

The interbank foreign-exchange market is where large banks trade currencies with each other in huge denominations. The quotes are posted as a two-sided price: a bid (what a dealer is willing to pay for the currency) and an ask (what a dealer will sell it for). The mid-market rate is the midpoint between the current bid and ask. It is the rate Reuters, Bloomberg, Google, and XE usually show. It is also the rate that absolutely no retail customer actually gets, because retail customers are not parties to the interbank market.

Retail banks take the interbank price and add a markup before quoting it to walk-in and digital customers. The markup is structured as a spread above and below the mid: the bank will sell the currency to you a little above mid, and buy it from you a little below mid. The size of that spread depends on the product.

Wire (송금) rates — often called “telegraphic transfer” or “TT” rates in Korean banking — are the tightest retail rates. Wires move electronically through SWIFT or a domestic equivalent; the bank does not have to hold physical notes, and the back-office cost per transaction is small relative to typical wire size. The spread at a major Korean retail bank is commonly in the ballpark of roughly 1% each way from mid, sometimes less for premium clients and major currency pairs.

Cash (현찰) rates are wider. Physical banknotes have to be airlifted, insured, vaulted, and inventoried against theft and spoilage. The spread commonly sits around 1.5–2% each way from mid for major currencies at a typical Korean retail bank, and widens sharply for exotic or low-volume currencies. “Cash-buy” is the rate at which the bank buys banknotes from you; “cash-sell” is the rate at which the bank sells banknotes to you.

The four retail quadrants — cash-buy, cash-sell, wire-buy, wire-sell — cover every retail operation: exchanging travel cash, depositing foreign notes, initiating an outbound wire, receiving an inbound wire. Your real cost is the difference between the rate you actually got and the mid-market rate at the same moment, expressed as a percentage of the amount transacted.

Data / Comparison

Rate typeWho quotes itTypical spread over midWhen you pay it
Mid-marketInterbank dealers0 (by definition)Only for interbank-scale transactions
Wire buy / sellRetail and digital banksRoughly 1% each way for major pairs, smaller for premium clientsOutbound wires, foreign stock brokerages, remittances
Cash buy / sellRetail banks, airport boothsRoughly 1.5–2% each way at a bank; substantially wider at airport booths and tourist-area exchangesTravel cash, exchanging notes left over from a trip
Card networkVisa / Mastercard / UnionPayCard network rate close to mid, plus issuer FX fee (often 0–3%)Foreign card purchases

A simple example clarifies the real cost. Imagine an exchange where the mid-market rate is exactly 1,300 KRW per USD. A bank posts cash-sell at 1,326 (a 2% markup) and wire-sell at 1,313 (a 1% markup). Buying $1,000 in physical cash at the counter costs you ₩1,326,000; sending the same $1,000 by wire costs you ₩1,313,000. The ₩13,000 gap is the cost of wanting physical notes instead of an electronic transfer — reasonable for a traveler, wasteful for an investor moving money to a brokerage.

To make this less abstract: in February 2026 I sent USD 5,000 from KEB Hana Bank to a friend in the US, and ran the same transfer through Wise as a comparison. Hana retail wire: KRW 20,000 outbound fee + roughly USD 20 deducted in transit by an intermediary correspondent + a wire-rate markup of about 1.05% — total drag about KRW 92,500. Wise: a flat fee around KRW 23,500 with the mid-market rate applied directly — total drag about KRW 23,500. One transfer, KRW 70,000 difference. For someone wiring quarterly, that is KRW 280,000 a year, KRW 1.4 million over five years.

Real-world Scenarios

Scenario 1 — Overseas travel. You need local cash for tips, taxis, small shops. The practical strategy is a mix: a moderate amount of cash exchanged at your home-country bank (cheaper than the airport), a no-FX-fee credit card for restaurants and hotels, and an ATM withdrawal abroad with a card that rebates foreign ATM fees as needed. Avoid the airport counter and the tourist-area “0% commission” booth — they almost universally hide their markup in the rate, which is 4–8% worse than a retail bank.

Scenario 2 — Overseas stock investing. You wire funds from a Korean bank to a brokerage that holds a USD account, or use a Korean brokerage that handles conversion internally. Wire rates apply. The spread between banks on the same day can be meaningful over a large amount, and some Korean brokerages run periodic FX discount promotions (예: FX 우대 90%) that narrow the spread substantially — worth checking before a large conversion.

Scenario 3 — Remittance to or from family abroad. Traditional bank wires incur outbound fees (₩10,000–₩30,000), intermediary-bank fees ($15–$40 deducted in transit on USD wires), and the wire spread. Specialist providers like Wise or Remitly compete on the combination. For small to medium amounts, specialists are typically cheaper; for very large amounts, a direct bank wire from a premium-client tier can be competitive once fee-waivers are applied.

Scenario 4 — Paying abroad with a credit card. The Visa or Mastercard network converts the transaction at a rate close to mid-market, and the card issuer may or may not add a foreign-transaction fee (often 1–3%). A no-FX-fee card is usually the cheapest way to pay retail abroad. Dynamic Currency Conversion (DCC) — the terminal asking “pay in KRW or local currency?” — is almost always worse than letting the card network do the conversion; merchants charge 3–8% for the DCC service and keep most of it. The Amsterdam example I opened with was exactly this trap. Reverse-tracing the receipts, restaurants ran an average DCC margin of 5.4% and the hotel hit 7.1%. Most major Korean and US issuers now expose a setting in the mobile app that forces foreign transactions through the card network in local currency, declining DCC at the issuer level even if a clerk taps the wrong button on the terminal — turning that on before any trip costs nothing and removes the most common single source of overcharging.

Common Misconceptions

“Airport exchange is cheapest.” It is typically among the most expensive options available. Rent and captive demand let airport counters widen their spreads dramatically. “No commission” signs usually mean the commission is baked into the rate. I once compared a same-day quote from an Incheon Airport booth against three downtown branches (KEB Hana, KB Kookmin, Woori) for a USD 100 cash exchange and the airport came in roughly KRW 4,000–6,000 worse — a 3–5% drag on a small ticket. Scaled to a typical KRW 1,000,000 traveler exchange, the airport convenience costs around KRW 30,000–50,000.

“Paying with a credit card abroad is free FX.” Only if the card explicitly charges no foreign-transaction fee. Many cards add 1–3% automatically. Check the terms before traveling. DCC is a separate, additional cost on top of the card’s own fee, and is worth consistently declining.

“The rate I see on Google is the rate I’ll get.” Google, XE, and Reuters all show the mid-market rate, and no retail customer transacts at mid. Always compare the quoted rate to the mid to see the spread you are paying.

“Bigger amounts get better rates automatically.” Not automatically. Larger amounts can negotiate better rates via a premium banking tier, a preferred-customer FX discount, or a specialist provider. But the default retail rate does not improve just because you are exchanging more — you have to ask or pick a channel designed for larger amounts.

Checklist

  1. What is today’s mid-market rate? Use it as the benchmark against every retail quote.
  2. Do you need physical cash or an electronic transfer? Cash spreads are wider.
  3. What is the total cost — spread plus fees? Some channels have narrow spreads and high fees, or vice versa.
  4. Is your card a no-FX-fee product? If yes, retail purchases abroad are often the cheapest channel.
  5. Decline DCC every time. Pay in local currency; let the card network convert.
  6. For large amounts, compare providers. Wire from a premium banking tier, Wise, broker FX — prices vary significantly.

The Patrache Studio exchange-rate calculator lets you input an amount and compare the four retail rates against mid-market in a single view, so the cost of picking “cash” instead of “wire” is explicit. For anyone with a loan denominated in a foreign currency, Loan Payment Types: Amortized vs Equal Principal vs Bullet pairs naturally — FX movement compounds the interest-structure choice. And if you are thinking about holding foreign assets for years (FX carry trades, foreign dividend portfolios), Compound Interest and the Rule of 72 is the math that actually decides whether the FX spread was worth paying.

References

Related Tool

calc.patrache.studio/finance/currency/