HealthCalcPro open-source calculator formulas
This is the open-source home of the formulas behind the free calculators on HealthCalcPro. Each one follows a named public source, such as the Social Security Administration or HUD, and each one has unit tests. The code is TypeScript, MIT licensed, and free to reuse.
The calculators and their sources
Full retirement age calculator
Social Security full retirement age from a birth date, including the January 1 and first-of-the-month rules, and the percent of the full benefit for claiming anywhere from 62 to 70. Source: Social Security Administration.
Divorce budget calculator
Solo monthly income against expenses after a separation, with HUD's housing cost-burden line (housing and utilities above 30% of income), an emergency fund target and savings runway.
Wedding budget calculator
A category split that always adds up to the total, cost per guest compared with The Knot's 2026 Real Weddings Study, and months to reach the savings goal.
Wake window calculator by age
Typical wake windows and nap counts for babies up to 24 months, with total sleep ranges from the American Academy of Sleep Medicine and the National Sleep Foundation.
Perimenopause and menopause symptom checklist
A printable, non-scored checklist based on the NHS symptom list, sorted by how often each symptom happens, to take to an appointment.
What things cost in 1957, in today's dollars
1957 prices from the Bureau of Labor Statistics' original 1959 bulletin, converted with the consumer price index (one 1957 dollar is about $11.92 today).
How the retirement math works
Full retirement age is 66 for people born 1943 to 1954, rises by two months a year for 1955 to 1959, and is 67 for 1960 and later. Claiming early reduces your own benefit by 5/9 of 1% for each of the first 36 months before full retirement age and 5/12 of 1% for each month beyond. Waiting adds 2/3 of 1% a month until 70. With a full retirement age of 67, that is 70% at 62 and 124% at 70.
import { calculateRetirement } from "./src/retirement";
calculateRetirement({ birthYear: 1962, birthMonth: 4, birthDay: 15, claimMonths: 62 * 12 }).percent; // 70Limits
These formulas are for information only and are not medical, legal or financial advice. Spousal and survivor Social Security benefits use different rules and are not covered. Wake windows are common rules of thumb, not a medical standard. The menopause checklist does not diagnose and gives no score.
Who makes this
HealthCalcPro is made by Melike and İsmail Günaydın. Melike designs the planners in our Etsy shop, HerRescueKits; İsmail, a software engineer, builds and tests the calculators. See our planners and books.