True FX Conversion Cost Calculator

What is foreign exchange conversion cost?

Foreign exchange (FX) conversion cost is the true total expense of converting one currency to another, measured against the mid-market (interbank) exchange rate. Most people focus on whether they "got a good rate," but the real cost is the sum of three charges: the exchange rate spread, explicit transaction fees, and any ATM or intermediary fees. These can add up to 3–8% at a traditional bank for international transfers.

The mid-market rate — the midpoint between the buy and sell rates on the global FX market — is the benchmark that Google, Reuters, and Bloomberg display. No retail customer receives the mid-market rate; every service marks it up. The question is by how much, and understanding this helps you select the cheapest provider and avoid losing hundreds of dollars on a large international transfer.

The FX cost formula

True conversion cost is calculated as the shortfall versus the mid-market rate:

Received Amount = Send Amount × (Mid-Market Rate × (1 − Spread%)) − Fixed Fee
FX Cost % = 1 − (Received Amount / (Send Amount × Mid-Market Rate))
FX Cost $ = Send Amount × Mid-Market Rate − Received Amount

Spread% — the percentage markup applied to the mid-market rate. Fixed Fee — any flat transaction fee charged. Mid-Market Rate — the interbank benchmark rate at the time of the transaction.

Worked example

You send $10,000 USD to a EUR bank account. Mid-market rate is 1.0850 (you should receive €10,850). Here's how different providers compare:

• Traditional bank (e.g., Chase wire transfer): Applies a ~3% spread and a $45 fee. You receive: $10,000 × 1.0850 × 0.97 − $45 = €10,475. Cost: $375 or 3.8% of transfer.
• Wise (formerly TransferWise): ~0.4% spread + ~$4.14 fee. You receive: $10,000 × 1.0850 × 0.996 − $4.14 = €10,802. Cost: $48 or 0.48%.
• Revolut (standard plan): ~0.3% spread on weekdays, no fixed fee. You receive approximately €10,817. Cost: ~$33 or 0.33%.
• Airport kiosk / hotel desk: Spreads of 8–12% are common. You receive €9,638–€9,982. Cost: $868–$1,212 on a $10,000 transfer.

On a $10,000 transfer, the difference between a bank and Wise is roughly $327. On a $50,000 real estate purchase abroad, that same differential is $1,635 — meaningful money for choosing the right service.

When to use the FX cost calculator

Use this calculator whenever you're converting significant sums and want to compare provider costs or understand the true cost of a past conversion.

• International wire transfers: Before sending money to a foreign bank account, enter the mid-market rate and each provider's offered rate to see which is cheapest for your amount and destination currency.
• Foreign property purchases: A $300,000+ property purchase abroad can lose $5,000–$15,000 to poor currency conversion. Specialist FX brokers (Moneycorp, OFX) often beat banks for large transfers.
• Expat salary management: US expats receiving salary in a foreign currency and repatriating funds monthly should optimize their transfer provider — even a 1% improvement on $5,000/month saves $600/year.
• Travel spending: ATM withdrawals abroad and credit card foreign transaction fees (typically 1–3%) are a form of FX cost. This calculator quantifies whether a no-FTF card (Charles Schwab, Fidelity, Wise debit) is worth carrying for international trips.

Common mistakes

FX cost mistakes are easy to make because the charges are often hidden in the rate itself, not shown as explicit fees.

• Comparing the provider's rate to yesterday's rate, not today's mid-market: Exchange rates move constantly. The only valid benchmark for conversion cost is the mid-market rate at the moment of your transaction. Comparing to a rate from 24 hours ago can mask a large spread.
• Ignoring receiving-bank fees: Many international wire transfers incur fees at the receiving bank as well as the sending bank. A $20–$30 intermediary bank fee (common in SWIFT transfers) reduces what your recipient actually receives. SEPA transfers within Europe typically avoid this.
• Using credit cards with FTF for large purchases abroad: A 3% foreign transaction fee on a $5,000 hotel bill or car rental is $150. Visa/Mastercard exchange rates are generally fair (within 0.5–1% of mid-market), but the FTF can make a credit card more expensive than a Wise or Revolut debit card.
• Transacting on weekends with Revolut: Revolut applies a 0.5–2% markup on weekend currency conversions (and for some currencies, a larger markup) because interbank FX markets are closed and they bear the overnight risk. This is disclosed in their fee schedule but easy to overlook.

Limitations of FX cost calculations

This calculator uses a snapshot mid-market rate that you enter. In practice, exchange rates fluctuate continuously during the trading day, and the rate you receive on a wire transfer may differ from the rate quoted at the time you initiate it — especially for bank transfers that process over 1–3 business days. Forward contracts, which lock in a rate for a future transfer, can eliminate this uncertainty for large transactions but typically require a commercial relationship with an FX broker.

The calculator also assumes a single transfer structure. For recurring transfers (e.g., monthly expat salary remittances), the true optimum may involve currency accounts, forward contracts, or limit orders available through specialist providers — features that go beyond simple spot-rate comparisons.

Frequently asked questions

What is the mid-market rate?

The mid-market rate (also called the interbank rate or spot rate) is the midpoint between the buy and sell prices quoted on the global foreign exchange market. It is the rate Google, Reuters, and Bloomberg display. No retail customer receives this rate directly — all retail FX providers mark it up. The markup is the source of profit for banks, money transfer operators, and currency exchange kiosks.

Is Wise always cheaper than my bank?

For most common currency pairs and moderate transfer sizes ($500–$50,000), Wise is significantly cheaper than traditional bank wire transfers. However, for very small amounts (under $100), the fixed fee component makes Wise less efficient. For very large amounts, specialist FX brokers (OFX, Moneycorp, Currencies Direct) may negotiate tighter spreads than Wise's published rates.

Are there transfer limits with Wise or Revolut?

Wise imposes per-transfer limits that vary by currency corridor and verification level — typically $1M+ for verified business accounts, lower for personal. Revolut's standard plan has a monthly limit on fee-free currency exchange (£1,000 equivalent for Standard, unlimited for Metal). For large property or business transfers, an FX broker with no hard limits and dedicated account management is often preferable.

What is a foreign transaction fee on a credit card?

A foreign transaction fee (FTF) is a surcharge of typically 1–3% applied by a credit card issuer on purchases billed in a foreign currency or processed through a foreign bank. The fee is charged on top of Visa/Mastercard's exchange rate (typically 0.5–1% above mid-market). Many premium travel cards waive this fee — Chase Sapphire, Capital One Venture, and all Charles Schwab debit card transactions are common examples.

Related calculators

FX cost is directly relevant to expat financial planning:

• FEIE Calculator — calculate your US tax savings from the Foreign Earned Income Exclusion, the most important tax provision for Americans living abroad.