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 →Percentage Calculator
Calculate percentages easily: find X% of Y, what % X is of Y, or percentage increase and decrease.
Open calculator →BMI Calculator
Calculate adult Body Mass Index from height and weight and see the matching WHO category range.
Open calculator →Age Calculator
Calculate exact age in years, months, days, total days lived, and countdown to your next birthday.
Open calculator →Savings Goal Calculator
Determine how much to save monthly to reach your target savings goal with compound interest.
Open calculator →Calorie Calculator
Estimate maintenance calories from BMR and activity, then plan deficit or surplus targets for weight goals.
Open calculator →Currency Converter
Convert world currencies (USD, EUR, GBP, CAD, AUD, JPY, INR, CHF) with live exchange rates and timestamp.
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 and contributions.
Open calculator →Protein Calculator
Estimate daily protein targets from weight, activity, and goals, with adjustments for pregnancy or lactation.
Open calculator →Tip Calculator
Calculate tip amounts, split bills easily among people, and see the exact cost per person.
Open calculator →Temperature Converter
Convert temperatures among Celsius, Fahrenheit, Kelvin, and Rankine with an all-scales comparison.
Open calculator →Date Calculator
Calculate exact days between two dates, or add/subtract days, weeks, and months from any date.
Open calculator →Due Date Calculator
Estimate a pregnancy due date from last period, ultrasound dating, conception date, or IVF embryo transfer.
Open calculator →
Browse by category
5 categories, 44 calculators and growing.
Financial
Plan mortgages, loans, investments, savings goals, and payoffs with free calculators. Each tool explains the formula assumptions, shows worked scenarios, and links to money guides.
16calculators →
Health
Estimate BMI, metabolism, calories, body fat, ideal weight, hydration, and heart rate zones. Clear wellness explainers so you understand what your numbers mean.
9calculators →
Everyday Math
Simple, fast calculators for standard arithmetic, percentages, dates, exact ages, and durations. Designed for quick answers on desktop and mobile with keyboard support.
5calculators →
Converters
Convert weight, length, area, volume, speed, currency, time, and temperature between common units with instant tables and clear conversion formulas.
9calculators →
Pregnancy & Cycle
Explore due dates, pregnancy timelines, ovulation, periods, and conception windows. Educational dating tools with clear limitations—always confirm prenatal care with your clinician.
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.