🧮 Free Online Calculators
Solve math problems, calculate statistics, and crunch numbers instantly. From basic percentages to advanced probability - all free and private.
34 free tools available
Percentage Calculator
Calculate percentages, percentage change, and find what percent one number is of another.
BMI Calculator
Calculate your Body Mass Index (BMI) with metric and imperial units.
Tip Calculator
Calculate tips and split bills between multiple people easily.
Loan & Mortgage Calculator
Calculate monthly payments, total interest, and see a full amortization schedule for any loan.
Age Calculator
Calculate your exact age in years, months, days, hours, and minutes from your date of birth.
Date Calculator
Calculate the number of days between two dates, or add and subtract days from any date.
Discount Calculator
Calculate sale prices, discounts, and savings. Enter original price and discount percentage or amount to find the final price.
Calorie Calculator
Calculate your daily calorie needs based on age, weight, height, activity level, and fitness goals. Uses the Mifflin-St Jeor equation.
Scientific Calculator
Full-featured scientific calculator with trigonometry, logarithms, factorials, memory functions, and calculation history.
GPA Calculator
Calculate your GPA on a 4.0 scale. Add courses with grades and credits. Supports semester and cumulative GPA.
Body Fat Calculator
Estimate body fat percentage using the US Navy method or BMI formula. Get body composition category and lean mass.
Average Calculator
Calculate mean, median, mode, standard deviation, variance, range, quartiles, and more from a set of numbers.
BMR Calculator
Calculate your Basal Metabolic Rate (BMR) and Total Daily Energy Expenditure (TDEE). Mifflin-St Jeor, Harris-Benedict, and Katch-McArdle formulas.
Ideal Weight Calculator
Calculate your ideal body weight using 5 scientific formulas: Robinson, Miller, Devine, Hamwi, and BMI-based methods.
Sleep Calculator
Calculate the best times to sleep and wake up based on 90-minute sleep cycles. Wake up between cycles feeling refreshed instead of groggy.
Pregnancy Due Date Calculator
Calculate your estimated due date from last period, conception, or IVF transfer. Track pregnancy milestones week by week with trimester progress.
Water Intake Calculator
Calculate your daily water intake based on weight, activity, and climate. Track glasses with a visual progress tracker.
Fraction Calculator
Add, subtract, multiply, and divide fractions and mixed numbers. Simplifies results automatically with decimal equivalents.
Quadratic Equation Solver
Solve ax² + bx + c = 0 with step-by-step solutions. Find real and complex roots, discriminant, and vertex. Shows the quadratic formula in action.
Blood Alcohol Calculator (BAC)
Estimate blood alcohol content based on drinks, weight, gender, and time. Uses the Widmark formula. For educational purposes only.
Standard Deviation Calculator
Calculate standard deviation, variance, mean, median, min, max, and range from any dataset. Step-by-step breakdown with population and sample SD.
Pace Calculator
Calculate running or cycling pace, finish time, or distance. Supports km and miles with race split tables for 5K, 10K, half marathon, and marathon.
Grade Calculator
Calculate your weighted grade average with letter grade and GPA. What-if analysis shows what you need on your final exam.
Probability Calculator
Calculate probability, combinations (nCr), permutations (nPr), coin flip odds, and dice roll probabilities.
Ratio Calculator
Solve proportions, simplify ratios, and scale dimensions. Find missing values in A:B = C:D.
Macro Calculator
Calculate daily protein, carbs, and fat needs based on your body, activity level, and fitness goals using the Mifflin-St Jeor equation.
Heart Rate Zone Calculator
Calculate your training heart rate zones for fat burn, cardio, and peak performance. Supports Max HR and Karvonen methods.
Matrix Calculator
Perform matrix operations: addition, subtraction, multiplication, transpose, determinant, inverse, and scalar multiplication.
Speed Calculator
Calculate speed, distance, or time from any two values. Supports km/h, mph, m/s, knots, and more.
Blood Pressure Checker
Check your blood pressure reading against standard categories. Get health insights based on systolic and diastolic values.
Protein Calculator
Calculate your daily protein intake based on body weight, activity level, and fitness goals. Get personalized recommendations.
World Population Clock
Watch the estimated world population grow in real-time. See births, deaths, and population by country.
Aspect Ratio Calculator
Calculate aspect ratios, resize dimensions proportionally, and find the perfect resolution for screens, images, and videos.
Unit Circle Explorer
Interactive unit circle with sine, cosine, and tangent visualizations. Click any angle to see exact values in degrees and radians.
Frequently Asked Questions
How accurate are these calculators?
All calculators use standard mathematical formulas and IEEE 754 floating-point arithmetic. Results are accurate to at least 10 decimal places for most calculations.
Can I use these for homework or exams?
These calculators are great study tools for checking your work and understanding concepts. Always verify results and show your work for academic assignments.
Do the calculators show the formula used?
Many calculators display the formula and step-by-step breakdown so you can understand the math behind the result.