Calcuit — Calculator tools online
Free calculators & blog for money, health & everyday math
Free online calculators for finance, health, and more. Fast, accurate, and easy to use on any device. Explore tools by category, then dig into guides and articles on the blog.
Why use Calcuit?
A focused calculator site — not a cluttered tool directory. Just the math you need, presented clearly.
Instant results
Every calculator updates live as you type. No submit buttons, no waiting — see your numbers immediately.
Reliable formulas
Built on established equations used in finance and health — Mifflin-St Jeor, loan amortization, BMI standards, and more.
Works on any device
Mobile-first layouts with floating previews on small screens. Use Calcuit on your phone, tablet, or desktop.
Free, no account
No sign-up, no paywalls, no downloads. Open a calculator and get answers in seconds.
Popular calculators
Jump straight to the tools people use most — mortgages, BMI, calories, loans, and more.
Mortgage Calculator
Estimate a fixed monthly mortgage payment and see how interest vs principal change over the loan term.
Open calculator →House Affordability Calculator
Estimate a home budget from income, debts, or a monthly housing number using common DTI guidelines and PMI rules.
Open calculator →BMI Calculator
Calculate adult Body Mass Index from height and weight and see the matching WHO category range.
Open calculator →Calorie Calculator
Estimate maintenance calories from BMR and activity, then plan deficit or surplus targets for weight goals.
Open calculator →BMR Calculator
Estimate basal metabolic rate with Mifflin-St Jeor, Harris-Benedict, or Katch-McArdle and map it to activity levels.
Open calculator →Auto Loan Calculator
Project car payments after down payment, trade-in, tax, and fees — then see total interest over the term.
Open calculator →Compound Interest Calculator
Compare simple vs compound growth with adjustable compounding frequency.
Open calculator →Protein Calculator
Estimate daily protein targets from weight, activity, and goals, with adjustments for pregnancy or lactation.
Open calculator →Pay Off Calculator
Free pay off calculator for mortgages and loans — model extra monthly or biweekly payments to see interest saved, months saved, and a faster payoff date.
Open calculator →Due Date Calculator
Estimate a pregnancy due date from last period, ultrasound dating, conception date, or IVF embryo transfer.
Open calculator →Ovulation Calculator
Project ovulation days and fertile windows for upcoming cycles from your last period and cycle length.
Open calculator →Temperature Converter
Convert temperatures among Celsius, Fahrenheit, Kelvin, and Rankine with an all-scales comparison.
Open calculator →Height Converter
Convert human height between centimeters, meters, and feet & inches for forms, charts, and fitness tools.
Open calculator →
Browse by category
4 categories, 25 calculators and growing.
Financial
Mortgage, loan, investment, and savings calculators for smarter money decisions.
9calculators →
Health
BMI, calorie, and wellness calculators to support your health goals.
6calculators →
Pregnancy & Cycle
Due dates, pregnancy timelines, ovulation, periods, and conception windows.
5calculators →
Converters
Quick unit conversions for weight, length, time, temperature, and height.
5calculators →
Guides & blog
Short explainers and practical articles that pair with our tools.
Mortgage payment basics
How fixed-rate mortgage payments split into interest and principal, what PITI means, and which Calcuit tools to use next.
- mortgage
- guide
Pregnancy dating at a glance
How due dates and gestational age are estimated from LMP, ultrasound, conception, or IVF — and why exact birthday prediction is rare.
- pregnancy
- guide
Understanding BMI
What Body Mass Index measures, how categories work, and why BMI is only one piece of a health picture.
- health
- bmi
- guide
More calculators on the way
We're adding tools across finance, health, and pregnancy regularly. Check back soon or tell us what you'd like to see.