A notepad calculator is a notepad with a calculator built in. You type math on a line, and the answer appears next to it, so each sum stays with the note it belongs to. On a Mac with macOS 15 Sequoia or later, Apple Notes already does this for basic sums: type 5 * 3 = and the answer appears. In Gubb, type gubb@math in a note, then end any line with = to get the result. gubb@currency and gubb@conversions handle money and units.

Gubb's calculator is basic. It handles arithmetic and powers, but not percentages, functions or variables. If you need those, Soulver and Numi are built for that job. This page covers Gubb's exact syntax, what fails, and how the options compare.

What a notepad with a calculator does

A regular calculator shows one number at a time and then forgets it. A notepad calculator keeps all of your working on the page: the question, the numbers and the answer, with your own notes in between. You can scroll back, fix a number and see what you were thinking.

Typical uses are splitting a bill, pricing a small project, converting a recipe, or checking a quote in another currency while you write.

The built-in options: Apple Notes and Spotlight

If you only need the occasional sum, start with what your Mac already has.

  • Apple Notes (macOS 15 Sequoia and later): type an expression such as 5 * 3 = in any note, and Notes shows the answer inline. It's free and syncs through iCloud to your iPhone and iPad.
  • Spotlight: press ⌘Space (Command-Space) and type a sum such as 1480*0.2. The result appears in the Spotlight window. This works for one-off answers, but nothing is kept on a page.

Windows Notepad doesn't do math, so on Windows you need a separate app. Gubb and Numi both run on Windows.

Do math in a Gubb note

Math mode works inside any Gubb note. You switch it on, and from then on every line that ends in = gets its answer added.

Turn on math mode

  1. Click into a note and type gubb@. A small menu opens next to the cursor.
  2. Choose Math with ↑ and ↓, then press Return or Tab. You can also click it, or type the full phrase gubb@math.
  3. Gubb replaces the phrase with "Math mode activated. Type calculations ending with = to evaluate." A blue badge, Math Mode Active · Type expression and end with =, appears at the bottom left of the note.
  4. Type an expression and finish it with =. For example, 12*3 = becomes 12*3 = 36.
  5. Press Esc when you want to leave math mode.
    Math mode isn't saved. After you restart Gubb, type gubb@math again to switch it back on. The answers already in your note are ordinary text, so they stay where they are.

What you can type

Gubb understands digits, decimals, + - * / ^ and parentheses. You can also use x or X for multiply and ÷ for divide. It ignores the symbols $, € and £ and thousands commas, so you can paste prices written that way.

You type Gubb adds Why it works
12*3 = 36 Basic multiplication
19.99 x 3 = 59.97 x counts as multiply
90 ÷ 4 = 22.5 ÷ counts as divide
(1200 + 340) / 4 = 385 Parentheses are respected
2^10 = 1024 ^ is a power
$1,250 + $480 = 1730 $ and commas are ignored

Results are calculated to 14 significant digits.

Gubb removes letters before it calculates, so put labels on the line above a calculation rather than on the same line. Also, while math mode is on, every line ending in = gets evaluated. Press Esc before you write ordinary text that ends with an equals sign.

Convert currency inside a note

  1. Type gubb@currency (or pick Currency from the gubb@ menu). The phrase is removed, and a green badge reads Currency Mode Active · Format: 100 USD to EUR.
  2. Type a line in the form <amount> <CODE> to <CODE>, using 3-letter currency codes. You can use in or -> instead of to.
  3. Press Return. Gubb adds the result to the end of the line, rounded to 2 decimals, along with the rate it used.

For example, 100 USD to EUR becomes something like 100 USD to EUR = 92.31 EUR (rate: 0.9231). Your numbers depend on the current rate. Lines like 250 GBP in JPY and 40 EUR -> USD follow the same format.

Hover over the badge to see Available Currencies. That list is fetched live, and the rates come from the Frankfurter API (frankfurter.dev). This mode needs an internet connection. Gubb doesn't store rates, so when you're offline nothing is added to the line and no error appears. Press Esc to leave currency mode.

Convert units inside a note

  1. Type gubb@conversions (or pick Conversions from the menu). A purple badge reads Measurement Mode Active · Format: 10 ft to m (press Enter).
  2. Type a line in the form <number> <unit> to <unit>, such as 10 ft to m.
  3. Press Return. Gubb replaces the line with 10 ft to m = 3.05 m.

Unit conversion works offline. Both units must be the same kind, and unit names aren't case-sensitive. Hover over the badge to see Available Measurement Units.

Kind Units Gubb accepts
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 or hectare(s), acre(s)
Volume m³, cm³, cc, L or liter(s) or litre(s), mL, gal or gallon(s) (US), qt or quart(s) (US), in³, ft³
Mass kg, g, mg, lb or lbs, oz, ton(s) (US short ton)
Temperature C, °C or celsius; F, °F or fahrenheit; K or kelvin

Whole numbers print as they are. Other results get 2 decimals, 3 decimals below 1, and 4 decimals below 0.1. Results below 0.0001, or 10,000 and above, appear in scientific notation.

Limits of Gubb's calculator, and workarounds

Gubb's notepad calculator is for quick sums while you write. It doesn't replace a full calculator app. These are the gaps as of version 1.0.1 (November 2026):

You might try What happens Do this instead
20% of 1480 = % and letters are stripped, so you won't get the percentage 1480 * 0.2 =
sqrt(16) = Function names are stripped, so you won't get 4 16^0.5 =
pi * 2^2 = Constants such as pi, e and phi don't work 3.14159265 * 2^2 =
rent = 1200, then rent * 12 = There are no variables Write the number on each line
5 sq ft to sqm Multi-word units ("sq ft", "cubic feet", "degrees C") aren't recognized 5 sqft to sqm
Garden: 10 ft to m The whole line is replaced, so your label is lost Put the label on the line above

The math badge itself can mislead you. When you hover over it, the Math Operations list includes %, sqrt(), abs(), log(), log10(), sin, cos, tan, pi, e and phi, but those entries don't currently work. Stick to the operators in the first table.

You also can't refer to an earlier answer or keep a running subtotal. If you work that way, look at Soulver or Numi.

Soulver and Numi

We make Gubb, so weigh our view accordingly. We've tried to be fair to Soulver and Numi, and both do more math than Gubb.

Soulver

Soulver calls itself "notepad, meet calculator", and math is its whole focus. It understands written-out math with conversions, such as 20% of $1,480, $100 in EUR and 240 km in miles. It also supports multi-word variables, references to earlier answers, subtotals, tags and Wolfram|Alpha integration. You can sync through iCloud and export to PDF, plain text or HTML email. Version 4 added a command-line tool.

As of November 2026, Soulver 4 is a one-time purchase of $59 with a 60-day free trial. It runs on Mac, iPad and iPhone, and the Mac version needs macOS 14.6 or later. We found no Windows version. Its makers describe a tradition of a paid major upgrade about every 7 years.

Pick Soulver if you do a lot of real calculating: budgets, invoices, trip costs, or anything with percentages or running totals.

Numi

Numi is a text calculator for Mac, Windows and Linux, with an open-source terminal version on GitHub. It handles currency, units, time zones, numeral systems and variables. It also has export and a notification widget.

As of November 2026, Numi is free to download. The free version limits how many notes you can keep, and a paid license unlocks unlimited notes and iCloud sync. The official site doesn't show the price clearly. Third-party listings range from $19.99 to $29.99, and Numi is also included in Setapp.

Pick Numi if you want variables and conversions across Mac and Windows, or on Linux.

For a closer look at these two, see Soulver vs Numi and our list of Soulver and Numi alternatives.

Compare at a glance

App Runs on Price (as of November 2026) Strong at Missing
Apple Notes Mac, iPhone, iPad Free Inline sums in notes you already sync Apple devices only
Gubb macOS, Windows $59 one-time for the Mac direct download, with a 7-day trial Math, currency and units next to notes, to-dos, clipboard history and timers Percentages, functions, variables; currency needs internet
Soulver Mac, iPad, iPhone $59 one-time, 60-day trial Percentages, variables, subtotals, Wolfram|Alpha No Windows version; calculator only
Numi Mac, Windows, Linux Free download; paid license price not published Variables, time zones, cross-platform Free version limits notes; calculator only

Which one to use

  • Use Apple Notes if you're on macOS 15 or later, your sums are occasional, and you want them on your iPhone too. You don't need anything else.
  • Use Gubb if you want quick arithmetic, currency and unit conversions in the same window as your scratch notes, checklists and clipboard history, and you can live without percentages or functions. The Mac direct download comes with a 7-day free trial of Gubb.
  • Use Soulver if math is the main job and you need percentages, running totals and references to earlier lines on Apple devices.
  • Use Numi if you need variables and time zones, or you work across Mac, Windows and Linux.

For unit and currency conversion with the tools your Mac already has, see how to convert units and currency on Mac.

If it doesn't work

Typing = does nothing. Math mode isn't on. Look for the blue badge at the bottom left. If it's missing, you pressed Esc or restarted Gubb, since the mode isn't saved between launches. Type gubb@math again.

The answer is wrong or missing. The line probably contains %, a function such as sqrt, a constant such as pi, or words. Gubb strips those before calculating. Rewrite the line with numbers and operators only, using the workarounds in the limits table.

A currency line stays unchanged. Check these in order:

  1. Make sure you pressed Return. Currency lines convert on Return, not on =.
  2. Check that both codes are 3 letters, such as USD, EUR or GBP.
  3. Check your internet connection. Hover over the green badge: "Failed to load currencies" means Gubb can't reach the rate service.

A unit conversion doesn't happen. Use the single-word unit forms from the table (sqft, not sq ft; C, not degrees C), and make sure both units are the same kind. For example, you can't convert kg to liters.

Text disappeared from a line. Unit conversion replaces the whole line with the result. Keep notes and labels on a separate line while measurement mode is on.

For the full reference, see the math and conversions section of the Gubb help center.

FAQ

Does Gubb's notepad calculator work offline?
Math and unit conversions work offline. Currency conversion needs internet, because Gubb fetches rates from the Frankfurter API and doesn't keep a copy.

Are the answers saved in the note?
Yes. The result is added as ordinary text, and Gubb saves notes automatically as you type. Only the mode itself switches off when you restart, so the answers stay in your note.

Is Gubb's calculator available on Windows?
Yes. Gubb is on the Microsoft Store for Windows, and the math commands are part of its notes editor.