holpxay n. [hol.ˈp’aj] number.
A notepad calculator where math just works. Type expressions, see results instantly.
Features
Arithmetic & Numbers
- Basic math with
+,-,*,/,^,!,mod, and parentheses - Alternative operators:
×,·,÷ - Percentages (
50%,200 * 15%), scientific notation, underscore separators - Hex (
0xFF), binary (0b1010), octal (0o777), arbitrary bases (ABC base 16) - Built-in constants (
pi,e,phi) and functions (sin,cos,sqrt,log,round,abs,random, …)
Units & Conversions
- 200+ built-in units across length, mass, time, temperature, data, energy, power, pressure, frequency, angle, and more
- Automatic cross-unit arithmetic:
5 km + 500 m,100 ft^2 + 5 m^2 - Derived units:
60 km/h,9.8 m/s^2,50 watts per square meter - Composite values:
5 ft 7 in,2 hr 30 min 15 sec - Flexible conversion syntax:
to,in,as,->,→ - Composite conversion targets:
171 cm to ft in - User-defined units:
150 apples / 30 apples/day
Date & Time
- Date literals, relative dates (
today,3 days ago,2 weeks from now) - Time values in 12h/24h format
- Date arithmetic:
now + 100 days,2038 Jan 19 - today - Timezone conversions:
18:30 Tokyo,now in London, UTC offsets - Unix timestamps:
1700000000 unix - Property extraction:
today to weekday,now to hour
Currency
- ISO codes, symbols, and names with live exchange rates
- Arithmetic and conversion:
100 USD + 50 EUR,100 USD to JPY - Derived currency units:
150 USD/person * 4 person
Variables & Conditionals
- Variable assignment:
price = 49.99 - Boolean expressions: comparisons,
&&,||,! - Conditionals:
if 5 > 3 then 100 else 200 - Bitwise operations:
&,|,xor,~,<<,>>
Output Formats
- Number bases (
to hex,to binary), fractions, scientific notation, percentages, ordinals - Precision control:
pi to 2 decimals,12345 to 3 sig figs - Date/time formats: ISO 8601, RFC 2822, RFC 9557, unix timestamps
Editor
- Markdown headings and inline comments (
#) - GFM syntax highlighting alongside live calculations
- Customizable themes, fonts, number/date formatting, and more