How to Convert Units and Currency in iOS 18 Calculator

Apple introduced a built-in conversion tool directly inside the native Calculator app with iOS 18, eliminating the need to rely on Spotlight, Siri, or third-party apps for quick conversions. This feature allows you to seamlessly convert dozens of different units, including lengths, weights, temperatures, and live foreign currencies, all within the standard calculator interface. This guide outlines how to enable the conversion mode, navigate the available units, and perform conversions on your iPhone.

How to Enable Conversion Mode

  1. Open the Calculator app on an iPhone running iOS 18.
  2. Tap the calculator icon located in the bottom-left corner of the screen.
  3. Toggle the Convert switch to the "On" position.

Once enabled, your calculator keypad remains visible, but the display split into two rows: the top row shows the starting value and unit, while the bottom row displays the converted output and target unit.

Selecting Categories and Units

By default, the calculator may load the last used conversion category. You can easily change both the category and the specific units:

  1. Tap the unit name (e.g., US Dollars, Miles, Celsius) on either the input or output row.
  2. A menu will appear displaying different measurement categories, such as:
    • Currency (USD, EUR, GBP, JPY, and dozens more)
    • Length (Inches, Feet, Meters, Kilometers, etc.)
    • Weight/Mass (Pounds, Ounces, Kilograms, Grams)
    • Temperature (Fahrenheit, Celsius, Kelvin)
    • Area, Volume, Speed, Time, Data, Energy, Power, and Pressure
  3. Select your desired unit from the list for both the input field and the output field.

Performing a Conversion

  1. Tap the top field and use the number pad to type the amount you want to convert.
  2. The bottom field automatically updates in real time to show the converted result.
  3. To reverse the direction of the conversion, tap the double-arrow icon located between the two fields.

How Currency Rates Are Updated

When converting currencies, the iOS 18 Calculator automatically fetches live foreign exchange rates whenever your device is connected to the internet. If you are offline or in airplane mode, the app uses the most recently fetched exchange rates, displaying the date and time of the last update below the conversion fields so you know how current the data is.