90 Free Online Calculators
Health, Finance, Math, Date & Time, Unit Conversion, Science, Digital, and Daily Life — all the calculators you need in one place.
No sign-up, no installation required. Calculate directly in your browser and share results instantly. All calculations run on your device — your data never leaves your browser.
Why Patrache Calculator?
Completely Free
Access all 90 calculators with no limits, no paywalls, and no hidden fees.
Privacy First
All calculations run in your browser. Your input data is never sent to any server.
Mobile Friendly
Optimized for every screen — desktop, tablet, and smartphone.
20 Languages
Available in Korean, English, Japanese, and 17 more languages worldwide.
Calculators by Category
Explore 90 specialized calculators across 8 fields.
Health
BMI, Calorie, BMR, Body Fat, Pregnancy Due Date and more
15Finance
Loan, Compound Interest, ROI, Investment, Currency and more
15Math
Percentage, Age, Fraction, Standard Deviation, Average and more
15Date & Time
D-Day, Days Between Dates, Timer, Stopwatch and more
12Unit Conversion
Length, Weight, Temperature, Volume, Area, Speed and more
12Science & Engineering
Ohm's Law, Molar Mass, Dilution, Decibel and more
8Digital & Dev
PPI/DPI, Aspect Ratio, Subnet, Base Converter, Color Code
5Daily Life
Electricity Cost, Tile, Paint, Alcohol, Fuel Cost and more
8Popular Calculators
Jump right into our most-used calculators.
BMI Calculator
Enter your height and weight to instantly calculate your Body Mass Index (BMI) and check your classification as underweight, normal, overweight, or obese, plus your healthy weight range.
Calorie Calculator
Calculate your daily calorie needs (TDEE) from age, gender, height, weight, and activity level to plan your diet for weight loss or gain. Free online calorie calculator that's easy to use.
BMR Calculator
Calculate your Basal Metabolic Rate (BMR) from age, gender, height, and weight using the Mifflin-St Jeor formula to find how many calories your body burns at rest. Free online tool.
Pregnancy Due Date Calculator
Enter your last menstrual period or conception date to find your estimated due date based on 280 days (40 weeks), with your current pregnancy week and trimester.
Compound Interest Calculator
Calculate how your money grows with compound interest. Enter principal, rate, time and frequency to see your final balance, total interest and the power of compounding.
Loan Calculator
Calculate your monthly loan payment, total interest, and total repayment instantly. Enter the loan amount, annual interest rate, and term to see a full amortization breakdown with this free loan calculator.
Percentage Calculator
Calculate percentages, percentage change, discounts, and ratio conversions in one tool. Find what X% of a number is or the percent difference between two values for free.
Age Calculator
Enter your date of birth to instantly calculate your exact age in years, months, and days, plus the total days you have lived and the days until your next birthday, free and online.
Random Number Generator
Generate random numbers within any custom min-to-max range. Choose integers or decimals, set the count, and allow duplicates or unique sets, using crypto-grade randomness.
Date Calculator
Calculate the number of days remaining until a target date or the days elapsed since a past date. Track birthdays, exams, events, and milestones with precision.
Days Between Dates
Calculate the exact number of days between two dates. Useful for tracking project durations, rental periods, age calculations, and any date difference needs.
About Patrache Calculator
Patrache Calculator (calc.patrache.studio) is a free online calculator collection designed to help you with everyday and professional calculations quickly and accurately. As of 2026, we offer 90 calculators across 8 categories: Health, Finance, Math, Date & Time, Unit Conversion, Science & Engineering, Digital & Development, and Daily Life.
From health calculators like BMI, Calorie, and Body Fat to financial tools like Loan Interest, Compound Interest, and ROI — from math utilities like Percentage, Fraction, and Standard Deviation to date calculators like D-Day and Days Between Dates — every calculator uses verified formulas to deliver reliable results.
All calculations are processed directly in your browser, so your input data is never transmitted to external servers. No sign-up or app installation is needed — anyone can start using it right away, with an optimized experience on both desktop and mobile devices.