What is an exchange rate?

An exchange rate tells you how much of one currency you need to get one unit of another. A rate written as USD/NGN 1,500 means one US dollar is worth 1,500 naira. The first currency (USD) is the base currency; the second (NGN) is the quote currency.

The important thing most explanations skip: there is no single exchange rate. At any moment the same pair of currencies has several prices:

• Buying rate (bid): what a dealer or bank will pay you for a currency.
• Selling rate (ask or offer): what a dealer or bank will charge you for it. This is always higher than the buying rate.
• Mid-market rate: the point halfway between buying and selling prices in the wholesale market, where banks trade with each other. It is also called the interbank rate. Most currency websites and search engines show a rate like this. It is a reference, not a price ordinary customers can usually trade at.
• Your rate: the rate a particular bank, app, money transfer service or bureau de change actually gives you. It includes their margin.

So when someone asks "what is the exchange rate?", the honest answer is "which one?" That is exactly why the spread matters.

What is an FX spread?

"FX" is short for foreign exchange. An FX spread is the difference between two of those prices. You will see the word used in two ways, and it helps to know both:

1. The buy-sell spread

The gap between a dealer's buying and selling price. If a bureau de change buys dollars at ₦1,480 and sells them at ₦1,520, the spread is ₦40. This is how dealers earn money and cover the risk that the rate moves while they hold the currency.

2. The margin over the mid-market rate

The gap between the rate you get and the mid-market rate. If the mid-market rate is ₦1,500 and your transfer app gives you ₦1,455 per dollar, you are paying a margin of ₦45 per dollar, which is 3%. Providers and articles also call this the markup or exchange rate margin.

The World Bank, which tracks what sending money home costs around the world, uses this second meaning. It counts the total cost of a transfer as the fee plus the margin by which the provider's exchange rate is worse than the interbank rate. It treats a provider that does not disclose its exchange rate as not transparent, because you cannot then split the cost into fee and margin.

Worked example: sending $500 to Nigeria

Suppose you are in the United States and want to send $500 to a family member's naira account. The mid-market rate is ₦1,500 per $1. Two providers quote you:

• Provider A: "No fees!" and a rate of ₦1,455 per $1.
• Provider B: a $5 fee added on top, and a rate of ₦1,490 per $1.

First, the formula. The exchange rate tells you what arrives:

The spread tells you what it cost. When you are receiving naira for foreign currency:

The working for Provider A: (1,500 − 1,455) ÷ 1,500 = 45 ÷ 1,500 = 3%. On $500, that is 500 × ₦45 = ₦22,500 that never reaches your family.

Provider B: (1,500 − 1,490) ÷ 1,500 = 0.67%, or ₦5,000. Add the $5 fee (worth ₦7,500 at the mid-market rate) and the total cost is ₦12,500, or 1.67% of the $500 sent.

What this means: the "no fee" provider is the more expensive one. For $5 more, your recipient gets ₦17,500 more. A fee is easy to see; a spread is not, so always compare the final amount received for the total you pay.

Buy and sell rates at a bureau de change

If you have ever changed cash at a bureau de change or with an "aboki" (the popular Nigerian name for an informal currency dealer), you have seen the buy-sell spread in action. The dealer has two prices:

Round numbers for illustration, not today's rates.

Buy $100 and you pay ₦152,000. Sell the same $100 straight back and you receive ₦148,000. The ₦4,000 you lose is the spread, even though no fee was charged and the "rate" did not change.

Spreads are not fixed. They tend to be wider for cash than for bank transfers, for small amounts, for less-traded currencies and when the market is moving fast. That is why the same provider can give you a different deal on a different day.

For Nigerian users: the official rate vs parallel rate is not a spread

In Nigeria you will often hear two dollar rates: an official rate used for regulated bank transactions and a parallel market (black market) rate quoted by street dealers and bureaux de change. The difference between them is sometimes loosely called a "spread", but it is a different thing:

• The official–parallel gap compares two separate markets.
• A spread is the gap between buying and selling within one market, or between your rate and the mid-market rate.

This matters when you check a quote. Measure a street dealer's rate against other parallel market quotes, and a bank's rate against the official reference. Comparing a parallel rate with the official rate will make almost any quote look "wrong" and tell you nothing about the dealer's margin. See both markets side by side on our official vs black market exchange rate page.

How to check the spread on any quote

1. Get the full quote. Note the exchange rate, every fee, and the exact amount the recipient will get. In the US, licensed remittance providers must show the exchange rate, fees and the amount the recipient will receive before you pay.
2. Find a reference rate for the same pair, at the same time. Use a mid-market rate for bank and app transfers. For a naira cash deal, use a parallel market reference such as our dollar to naira rate page.
3. Work out the margin. Subtract, divide by the reference rate and multiply by 100, using the right direction from the example above.
4. Add the fees and compare the totals. The best offer is the one that delivers the most money for the total you pay, not the one with the lowest fee or the best-sounding rate.

Just want to know what an amount is worth? The naira currency converter converts between naira and the major currencies at parallel market rates, and the naira value calculator shows the official and parallel value side by side.

Common mistakes

• Believing "zero fee" means free. The cost can sit entirely in the rate, as with Provider A above.
• Comparing against the wrong reference. A parallel market quote compared with the official rate, or a bank rate compared with a parallel rate, tells you about the gap between two markets, not about the provider's margin.
• Comparing rates from different times. Rates move. A reference from yesterday against a quote from today can make a fair offer look bad or a bad one look fair.
• Mixing up the direction. ₦1,500 per $1 and $0.000667 per ₦1 are the same rate written two ways. Make sure both numbers you compare are written the same way round.
• Forgetting costs outside the quote. Intermediary banks or the receiving bank can deduct charges on some international bank transfers. See what to do when the full amount did not arrive.
• Judging a rate without the amount. A small margin on a large sum can cost more than a large margin on a small one. Always turn the percentage into naira.

When the simple answer doesn't apply

• No conversion, no spread. If a bank wire arrives in dollars and is credited to a dollar account, such as a Nigerian domiciliary account, no exchange rate margin is charged on arrival. You meet the spread later, when you convert. This does not apply to money sent through licensed money transfer operators, which must pay out in naira in Nigeria. See how international money transfers work.
• Paying by card abroad. Your bank or card provider sets the conversion rate, and some card terminals abroad offer to charge you in your home currency. In the EU, card providers must state their currency conversion charges as a percentage markup over the European Central Bank's reference rate. Elsewhere, you may have to work it out yourself.
• Very large transfers. Businesses and people moving large sums can often ask for a better rate. The spread is frequently negotiable at that level.
• Rates you can lock. Some providers hold a quoted rate for a set time. Once locked, later market moves don't change your rate, in either direction.

What this means for you

• Treat the exchange rate as the price and the spread as the cost.
• Before you send or change money, note the mid-market (or correct market) reference rate at that moment.
• Ask every provider for the amount the recipient will get, and compare totals.
• Turn percentages into naira so you can see what the difference means in real money.

Sources

• United Nations Statistics Division, SDG indicator 10.c.1 metadata (World Bank definitions of total remittance cost, exchange rate margin and transparent services), last updated 27 March 2026.
• World Bank, Remittance Prices Worldwide.
• Consumer Financial Protection Bureau, Remittance Transfer Rule small entity compliance guide (required pre-payment disclosures).
• EUR-Lex, Regulation (EU) 2019/518 (currency conversion charges stated as a markup over ECB reference rates).
• AbokiCalculator rate feed: parallel market quotes and the official reference from Open Exchange Rates, as described in our methodology.

Last reviewed 24 September 2026. Spot an error? Tell us through our corrections page.