Calculators online tools — same implementation for humans and agents · 30 tools
root:calculator·Human page + Agent API · same engine
Calculate exact age from birth date
date-diff-age
m² hectare mu ft²
si-unit-tables
Simplify resolution to ratio, or solve width/height from ratio
gcd-ratio
Body mass index
life-utils
Estimate token cost from Router-aligned frontier price card
price-card+js-tiktoken
Count characters, bytes, lines, and whitespace
char-stats
Convert B KB MB GB TB
unit-utils
Days between two dates
std-date
Validate or calculate the GS1 check digit in bulk: GTIN-8/12/13/14, SSCC-18, GLN-13
gs1-mod10
Milliseconds epoch ↔ ISO 8601
Date
m km cm inch ft yd mile
si-unit-tables
Fixed-payment loan schedule: per-period interest, principal and balance, total interest, early payoff with extra payments, and the crossover period where principal first exceeds interest
annuity-amortization
Convert solar and lunar dates
lunar-javascript
Equal installment / principal mortgage schedule summary
mortgage-formulas
Convert integers between bases 2–36
std-number
Percentage of / what percent
life-utils
Percent change from A to B
pct-change
Estimate reading time for CJK + Latin text
reading-time-heuristic
Arabic ↔ Roman numerals converter
roman
m/s km/h mph knots
si-unit-tables
Celsius Fahrenheit Kelvin
si-unit-tables
Convert times across timezones with dayjs
dayjs
Calculate tip and split by party size
tip-math
Exact token counts via js-tiktoken
js-tiktoken
Convert between unix timestamps and ISO dates
std-date
L mL gallon m³
si-unit-tables
Find the weekday for a date
Date
kg g lb oz ton
si-unit-tables
CJK-aware word count via Intl.Segmenter
Intl.Segmenter
Compare the same instant across IANA timezones with dayjs
dayjs
