The fastest way to convert units on a Mac is Spotlight. Press ⌘Space (Command-Space), type something like 10 ft in m or 100 usd in eur, and the answer appears at the top of the results. For a converter with unit categories, use the Calculator app. If you want the result to stay in your notes, a notepad-style app such as Gubb or Soulver lets you type the conversion on a line and get the answer on that same line.
Convert units on a Mac with Spotlight
Spotlight is built into every Mac and needs no setup.
- Press ⌘Space to open Spotlight.
- Type the amount, the unit,
in, and the target unit. Examples:5 kg in lbor10 ft in m. - Read the answer at the top of the results.
For currency, type the amount and 3-letter currency codes, for example 250 gbp in usd. Currency results depend on exchange rates fetched online, so you need a connection for current rates.
What Spotlight can't do: it keeps no record. When you close Spotlight the answer is gone. That's fine for a one-off check. If you're converting a list of measurements for a recipe, a packing list or a spec sheet, you'll be retyping or copying each result somewhere else.
Convert units with the Calculator app
Calculator has a converter with unit categories, including currency. Where you find it depends on your macOS version.
macOS 14 Sonoma
- Open Calculator (press ⌘Space, type "Calculator", press Return).
- Type the number you want to convert.
- Open the Convert menu in the menu bar and choose a category, such as length, temperature or currency.
- In the dialog that opens, pick the unit you're converting from and the unit you're converting to, then confirm.
- The result replaces the number in the display.
macOS 15 Sequoia and macOS 26 Tahoe
Calculator was redesigned in macOS 15, and the converter is now part of the main window. Turn on the Convert option (look in the View menu). The window then shows two rows with unit pickers: type in one row and the converted value appears in the other.
Currency in Calculator also relies on exchange rates downloaded from the internet.
What Calculator can't do: like Spotlight, it converts one value at a time, and the answer isn't saved next to anything else you're working on.
Convert units inline in your notes with Gubb
Gubb is our scratchpad app for Mac (also available for Windows). Its conversion mode works inside a note: you write 10 ft to m, press Return, and the answer is written into the line. This helps when you're converting several values and want to keep them together, such as furniture measurements or a recipe you're scaling.
Unit conversions work offline. Currency needs internet (see the next section).
Steps
- Click into a Gubb note.
- Type
gubb@conversions. Or typegubb@and pick Conversions from the menu that appears (↑ and ↓ to choose, then Return or Tab). - A purple badge appears: Measurement Mode Active · Format: 10 ft to m (press Enter).
- Type a conversion on its own line in the form
<number> <unit> to <unit>, for example10 ft to m. - Press Return. The line becomes
10 ft to m = 3.05 m. - Press Esc when you're done to leave measurement mode.
To check which units are available without leaving the note, hover over the badge. It shows a list titled Available Measurement Units.
Supported units
Units are case-insensitive. Use the single-word forms below.
| Kind | Units you can type |
|---|---|
| Distance | m, cm, km, in, ft, mi, yd (and spelled-out forms) |
| Area | sqm or m², sqcm or cm², sqkm or km², sqft or ft², sqin or in², ha, hectare(s), acre(s) |
| Volume | m³, cm³, cc, L, liter(s), litre(s), mL, gal or gallon(s) (US), qt or quart(s) (US), in³, ft³ |
| Mass | kg, g, mg, lb, lbs, oz, ton(s) (US short ton) |
| Temperature | C, °C, celsius, F, °F, fahrenheit, K, kelvin |
Some example lines:
5 kg to lb
70 F to C
2 gal to L
1200 sqft to sqm
3 acres to ha
How results are formatted
- Whole numbers are shown as is.
- Other results get 2 decimals, 3 decimals below 1, or 4 decimals below 0.1.
- Very small results (below 0.0001) and very large ones (10,000 and above) can appear in scientific notation.
Limits of Gubb's unit mode
- The whole line is replaced. Anything else on that line, like a label, is overwritten. Put each conversion on its own line and write labels on the line above.
- Multi-word units don't match.
sq ft,cubic feetanddegrees Cwon't convert. Usesqft,ft³andC. - Both units must be the same kind.
5 kg to mwon't convert. - Use
to. The documented format is10 ft to m. Avoidinbetween units here, sinceinis also the unit for inches. - No cooking or speed units. Cups, tablespoons and km/h aren't in the list. Try Spotlight or Calculator for those.
Convert currency inline with Gubb
Currency mode works the same way, with a different trigger.
- In a note, type
gubb@currency. The phrase disappears and a green badge appears: Currency Mode Active · Format: 100 USD to EUR. - Type a line in the form
<amount> <CODE> to <CODE>using 3-letter currency codes.inand->also work, so100 USD in EURand100 USD -> EURare both valid. - Press Return. Gubb adds the result (to 2 decimals) and the exchange rate to the end of the line, for example
100 USD to EUR = 92.31 EUR (rate: 0.9231). Your numbers depend on the current rate. - Press Esc to leave currency mode.
How currency mode differs from unit mode:
- It appends the result to your line. Unit mode replaces the line.
- It needs internet. Rates and the currency list come from the Frankfurter API (frankfurter.dev). Hover the badge to see Available Currencies, loaded live.
If you're offline, pressing Return adds nothing and shows no error, and the currency list shows Failed to load currencies. Gubb doesn't cache rates, so there's no offline fallback. For quick sums in the same note, Gubb also has a math mode (gubb@math) that works out lines ending in =. It handles + - * / ^ and brackets, but not percentages, functions or variables, even though the badge's popover lists some of them. Our notepad calculator guide compares it with other options, and the Gubb help center section on math and conversions has the full reference.
Soulver: when conversions are part of bigger calculations
If your conversions feed into larger calculations, a dedicated notepad calculator does more than Gubb. As of November 2026, Soulver 4 is a one-time $59 purchase with a 60-day free trial, and one purchase covers Mac, iPad and iPhone. It needs macOS 14.6 or later.
Soulver handles lines like 20% of $1,480, $100 in EUR and 240 km in miles, plus multi-word variables, references to earlier answers and subtotals. It syncs through iCloud and exports to PDF, plain text or HTML email.
What it doesn't do: it's only a calculator, with no to-do lists, clipboard history or timers, and we found no Windows version.
Pick Soulver if your notes are mostly calculations: budgets, quotes, trip costs with percentages and running totals. Pick Gubb if conversions are an occasional extra in notes you're already writing, alongside checklists, a timer and clipboard history. For other options, see Soulver and Numi alternatives.
Which method to use
| Method | Where you type | Currency | Result stays in your notes | Price (as of November 2026) |
|---|---|---|---|---|
| Spotlight | Anywhere, via ⌘Space | Yes, needs internet | No | Free, built in |
| Calculator | Calculator window | Yes, needs internet for current rates | No | Free, built in |
| Gubb | A Gubb note | Yes, 3-letter codes, needs internet | Yes | $59 one-time, 7-day free trial |
| Soulver | A Soulver sheet | Yes | Yes | $59 one-time, 60-day free trial |
- One quick conversion: Spotlight.
- Browsing unit categories: Calculator.
- A list of conversions you want to keep in a note: Gubb.
- Conversions mixed with percentages, variables and totals: Soulver.
Gubb is a $59 one-time purchase, and you can download the 7-day free trial without an account.
If a conversion doesn't work
Spotlight shows search results but no conversion. Spotlight lets you turn result categories on and off. Open System Settings, search for "Spotlight", and check that calculator and conversion results are enabled (the labels vary by macOS version). Then try a shorter form, such as 10 ft in m instead of 10 feet to meters.
Spotlight or Calculator won't convert currency, or the rate looks old. Both need an internet connection to get current exchange rates. Check that you're online and try again.
Pressing Return in Gubb just starts a new line. The mode isn't active. Look for the purple (units) or green (currency) badge. If it's missing, type gubb@conversions or gubb@currency again.
Gubb ignores a unit like "sq ft" or "degrees C". Only single-word units match. Use sqft or ft², and C or °C. Hover the badge to see the full list.
The label I typed before the conversion disappeared. In unit mode, Return replaces the whole line. Keep each conversion on its own line, with any notes on the line above.
Gubb currency mode does nothing. You're probably offline, or a currency code isn't one the service knows. Hover the badge: if it shows Failed to load currencies, connect to the internet. Otherwise, check that both codes are 3 letters and appear in the list.
FAQ
Can I convert currency on a Mac without internet?
Not with current rates. Spotlight, Calculator and Gubb all get rates online, and Gubb adds nothing to the line when it can't reach its rate service.
Where do Gubb's exchange rates come from?
From the Frankfurter API (frankfurter.dev). The badge's popover credits it, and Gubb only contacts it while you're in currency mode.
Can Gubb convert cooking measurements like cups?
No. Gubb supports distance, area, volume (metric, US gallons and quarts, cubic units), mass and temperature. For cups and spoons, try Spotlight or Calculator.