Kids & Family Calculators
Free family calculators for child growth percentiles, height prediction, due dates, and the cost of raising a child. Friendly tools for parents and parents-to-be — for guidance, not medical advice.
8 free kids & family calculators
Child Growth Percentile Calculator
Calculate height or length, weight, and BMI reference percentiles from birth to 19 using WHO standards and the WHO 2007 reference. Educational, not diagnostic.
Child Height Predictor Calculator
Predict a child’s adult height with the Khamis-Roche method or the mid-parental (Tanner) formula. Shows the estimate, its range, and the limits of both methods.
Pregnancy Due Date Calculator
Calculate your pregnancy due date based on your last menstrual period or conception date. See how many weeks pregnant you are and important milestones.
LEGO House Calculator
Calculate how many LEGO bricks you need to build a life-size house. Get brick counts, total cost, weight, and build time estimates for any home size you choose.
Santa Delivery Speed Calculator
Calculate the ridiculous speed Santa needs to deliver presents worldwide. See stops per second, Mach number, and g-forces for his magical Christmas journey.
Hogwarts Tuition Calculator
Calculate the cost of attending Hogwarts School of Witchcraft and Wizardry. Estimate tuition, supplies, wands, brooms, owls, and total 7-year education costs.
Conception Date Calculator
Estimate your conception date from your due date, last menstrual period, or baby's birth date. See your fertile window and how many weeks pregnant you are.
Cost of Raising a Child Calculator
Estimate the total cost of raising a child to age 18 by region, income, and category. Based on USDA data with inflation adjustments and a full breakdown.