calced

A notepad calculator that evaluates math expressions in plain text files. Available as a CLI tool and a web app.

Why calced?

Spreadsheets are overkill for quick calculations. REPLs lose context once you close them. calced keeps your math in plain text files where results stay next to the expressions, files can be versioned and diffed, and you use whatever editor you want.

Compared to other notepad calculators:

• Tiny, no dependencies — the CLI is a single 47KB Python file (stdlib only), the web app is a single 52KB HTML file. No build step, no node_modules, no Electron.
• Works offline — both versions run entirely locally. Save the HTML file or install the CLI and you're set.
• Both CLI and web — same syntax, same test suite, but well adapted to each environment.
• Stable results — shared web URLs include the major version, so they won't break on updates. Files store results inline. All configuration is inside the documents.

Web

Open the web app in a browser.

CLI

calced <file>           # evaluate and update file in place
calced -s <file>        # print result to stdout (don't modify file)
calced -w <file>        # watch for changes and auto-update
calced -w -s <file>     # watch and print (clears screen on change)
calced -u <file>        # print shareable web URL

Installation

Requires Python 3.9+. Any typical Python install method works (pip install calced, etc.).

# Install as a CLI tool
uv tool install calced

# Or run without installing
uvx calced <file>

# Or just grab the single-file script and run it directly
python calced.py <file>

How it works

Write math anywhere in a plain text file. Results are appended inline as # => result comments. Non-math lines are left untouched.

rent 1500                               # => 1_500 │
groceries 200 + 150                     # =>   350 │
utilities 80 + 45 + 30                  # =>   155 │
total                                   # => 2_005 ┘

_{Try in web app}

Results are aligned and updated in place each time you run the CLI (or automatically in watch mode), or live as you type in the web app.

Features

Basic arithmetic

2 + 3                                   # =>     5
10 * (4 + 6)                            # =>   100
2 ^ 10                                  # => 1_024
17 % 5                                  # =>     2

_{Try in web app}

Variables

income = 5000                           # => 5_000
tax_rate = 22%                          # =>     0.22
tax = income * tax_rate                 # => 1_100
after_tax = income - tax                # => 3_900

_{Try in web app}

Percentages

50% of 300                              # => 150
200 + 15%                               # => 230
200 - 10%                               # => 180
10 as % of 50                           # =>  20

_{Try in web app}

SI prefixes

1k                                      # =>         1_000
1M                                      # =>     1_000_000
1.5G                                    # => 1_500_000_000
500n * 2                                # =>             0.000001

_{Try in web app}

Supported: k/K (kilo), M (mega), G (giga), T (tera), P (peta), E (exa), m (milli), u/μ (micro), n (nano), p (pico), f (femto), and more.

Unit conversions

5 km in miles                           # =>     3.106855961
100 C in F                              # =>   212
1 gib in mib                            # => 1_024
60 min in hr                            # =>     1
1 gal in l                              # =>     3.78541

_{Try in web app}

Supported dimensions: length, mass, temperature, data, time, volume. Use in or to.

Rate conversions

Define exchange rates (or any conversion rate) with @rate, then convert using in.

@rate USD/EUR = 0.92
100 USD in EUR                          # => 92
50 EUR in USD                           # => 54.34782609

_{Try in web app}

Functions

sqrt(16)                                # => 4
round(3.14159, 2)                       # => 3.14
min(5, 2, 8)                            # => 2
max(1, 9, 3)                            # => 9
log10(1000)                             # => 3
sin(0)                                  # => 0

_{Try in web app}

Available: sqrt, abs, floor, ceil, round, log, log2, log10, sin, cos, tan, asin, acos, atan, exp, min, max

Constants

pi * 2                                  # => 6.283185307
e ^ 1                                   # => 2.718281828

_{Try in web app}

Date arithmetic

2025-01-15 + 3 days                     # => 2025-01-18
2025-01-31 + 1 month                    # => 2025-02-28
2025-03-01 - 2025-01-01                 # => 59

_{Try in web app}

Supports days, weeks, months, years. Subtracting two dates returns the difference in days. today, tomorrow, and yesterday work as keywords.

Totals

The total (or sum) keyword sums all numeric results since the last # heading or start of file.

rent 1500                               # => 1_500 │
groceries 350                           # =>   350 │
utilities 155                           # =>   155 │
total                                   # => 2_005 ┘

_{Try in web app}

Blank lines are ignored in the total; headings reset it. Each total also resets the running sum, so consecutive totals act as subtotals:

food 300                                # => 300 │
transport 100                           # => 100 │
total                                   # => 400 ┘
clothing 50                             # =>  50 │
total                                   # =>  50 ┘

_{Try in web app}

total resolves to a value, so it works inside expressions and assignments:

100                                     # =>   100 │
200                                     # =>   200 │
300                                     # =>   300 │
total * 2                               # => 1_200 ┘

_{Try in web app}

Number formats

Numbers can be written with commas or underscores as separators (1,000 or 1_000), in hex/binary/octal (0xFF, 0b1010, 0o77), or in scientific notation (1.5e3).

Trailing annotations

Parenthetical notes after an expression are ignored:

celo_price = 0.08 (see http://coinmarketcap.com)  # => 0.08

_{Try in web app}

Format directives

Control output formatting with @format and @separator directives. These apply to all subsequent lines until changed.

1000000                                 # => 1_000_000
@format = fixed(2)
1000000                                 # => 1_000_000.00
@format = scientific
1000000                                 # => 1.00e+06
@separator = comma
@format = minSig(3)
1000000                                 # => 1,000,000

_{Try in web app}