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How to Convert Currency Manually

Currency conversion multiplies the source amount by an exchange rate. The challenge is knowing the current rate.

  1. Find the exchange rate for your currency pair. Rates are quoted as '1 USD = 0.92 EUR', meaning one US dollar buys 0.92 euros.
  2. Multiply your amount by the rate: Amount × Rate = Converted Amount. For example, 100 USD × 0.92 = 92 EUR.
  3. For the reverse conversion, divide instead: 100 EUR ÷ 0.92 ≈ 108.70 USD. Equivalently, multiply by the inverse rate (1 ÷ 0.92 ≈ 1.087).
  4. Be aware of fees. Banks and services add a margin (spread) on top of the mid-market rate, so the rate you receive will be less favourable.
  5. For large transfers, compare rates from multiple providers (banks, fintech apps, forex bureaus) to minimise costs.

Currency Conversion Formula

Converted Amount = Source Amount × Exchange Rate. The exchange rate is the price of one unit of the source currency in terms of the target currency. Rates are determined by supply and demand in global foreign-exchange markets, influenced by interest rates, inflation, trade balances, and geopolitical events. The mid-market rate (also called the interbank rate) is the midpoint between the buy and sell price — it is the fairest rate, but retail customers typically receive a rate with a spread on top.

Why Use Our Currency Converter?

  • Live mid-market rates — sourced from the Open Exchange Rate API, refreshed hourly.
  • 44 major currencies — covering USD, EUR, GBP, INR, JPY, and many more.
  • Local caching — rates are stored in your browser for one hour so repeat conversions are instant and reduce API calls.
  • Swap and compare — one-tap swap button and a quick-convert panel showing five major currencies at once.
  • No tracking — we do not log which currencies you convert or the amounts involved.

Frequently Asked Questions

How often are exchange rates updated?

Rates are fetched from the Open Exchange Rate API and cached in your browser for one hour. Each time the cache expires and you convert again, fresh rates are fetched automatically.

Why do exchange rates fluctuate?

Exchange rates are driven by supply and demand in global forex markets. Key factors include central-bank interest rates, inflation differentials, trade balances, political stability, and market sentiment.

Is the rate shown the same as what my bank offers?

The rate shown is the mid-market (interbank) rate — the fairest benchmark. Banks and money-transfer services add a margin (spread) on top, so the rate you receive will be slightly less favourable. Compare providers to minimise that spread.

Can I convert historical amounts?

This tool uses current live rates. For historical conversions (e.g. what was 100 USD worth in EUR on 1 Jan 2020), you would need a historical-rate API, which is on our roadmap.

Which currencies are supported?

The converter includes 44 of the world's most-traded currencies, from USD and EUR to INR, BRL, NGN, and VND. The underlying API provides 150+ currencies; we display the most commonly used ones for clarity.

Is my conversion data stored?

No. The only data stored is the exchange-rate cache in your browser's localStorage (for performance). Your amounts and currency choices are never sent to ZeroKit servers.