Everyday Calculators
Last updated: October 2026
Age Difference Calculator (Between Two Birthdays)
Find the exact age difference between two people from their dates of birth: who is older and by how many years, months and days, or the gap in total days, weeks, months or decimal years.
Cat Age Calculator (Cat Years to Human Years)
Convert your cat's age to human years with the veterinary chart behind the AAHA/AAFP feline life-stage guidelines: 15 at one year, 24 at two, then 4 human years per cat year.
Chronological Age Calculator (Years; Months; Days)
Work out a child's or adult's exact chronological age on a test date in years, months and days (7;1;23), the format standardized tests ask for.
Dog Age Calculator (Dog Years to Human Years)
Convert your dog's age to human years by size class (small, medium, large, giant) with the veterinary table used by the AVMA and AKC, or with the 2020 DNA-methylation formula 16 × ln(age) + 31.
Hat Size Calculator
Turn your head circumference (cm or inches) into a US fitted hat size (6 7/8, 7 1/4 …), the UK size, the metric size and the S/M/L letter size, with a full hat size chart.
Men's to Women's Shoe Size Converter
Convert a men's shoe size to the women's size for the same foot, or a women's size to men's.
Ring Size Calculator
Find your ring size from the inside circumference or diameter of a ring that fits, or from a string wrapped around your finger, and convert between US, UK, EU/ISO (mm) and Japanese sizes.
Shoe Size Conversion
Convert shoe sizes between US men's, women's, kids and youth, UK, EU, Japan, Mexico, China, Korea, Brazil, Australia, and foot length in cm, mm or inches.
Women's Pant Size Calculator
Find your US women's pant size from your waist and hip measurements (inches or cm), with the UK, EU and Australian size and the jeans waist (W) size, using the ASTM standard body-measurement table.
Pet Age Calculator (Dog + Cat Years)
Quick dog-or-cat converter to human years.
Love Calculator
A pure-entertainment 'compatibility' score built from two names.