🧮 Free Online Calculators
Solve math problems, calculate statistics, and crunch numbers instantly. From basic percentages to advanced probability - all free and private.
63 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.
Love Calculator
Fun love calculator! Enter two names to find your love compatibility percentage. Shareable results with fun messages.
Zodiac Sign Calculator
Enter your birthday to find your zodiac sign, personality traits, strengths, weaknesses, compatibility, lucky numbers, and ruling planet.
Scientific Notation Converter
Convert numbers to/from scientific notation and perform calculations (add, multiply, divide) with step-by-step solutions.
Pregnancy Calculator
Calculate your pregnancy week, trimester, and due date. Week-by-week development highlights, key milestones, and progress visualization.
Dog Age Calculator
Calculate your dog's age in human years using the modern breed-size formula. Small, medium, large, and giant breeds with life stage info.
Calorie Counter
Track daily calories and macros with a built-in database of 50+ foods. Portion tracking, meal categories, macro pie chart, and daily goals.
Ideal Weight Calculator
Calculate ideal body weight using Devine, Robinson, Miller, and Hamwi formulas. Input height and gender for a recommended weight range.
Payroll Calculator
Estimate net pay after federal income tax, Social Security, and Medicare. Supports multiple pay frequencies and filing statuses.
Stock Dividend Calculator
Project dividend income growth with DRIP reinvestment. See yield on cost, annual income, and total return over time.
Property Tax Calculator
Calculate property taxes with assessment ratio, tax rate, and exemptions. Annual and monthly estimates. Compare appeal scenarios.
Blood Type Calculator
Calculate possible blood types for a child based on parents' blood types. Shows ABO and Rh factor probabilities.
Period Calculator
Track your menstrual cycle, predict next periods, and estimate ovulation windows. Supports variable cycle lengths.
TDEE Calculator
Calculate your Total Daily Energy Expenditure based on BMR, activity level, and fitness goals. Includes macro breakdown.
Concrete Calculator
Calculate how much concrete you need for slabs, columns, footings, and stairs. Results in cubic yards, cubic meters, and bags.
Paint Calculator
Estimate how much paint you need for walls and ceilings. Accounts for doors, windows, and number of coats.
Tile Calculator
Calculate how many tiles you need for floors, walls, or backsplashes. Includes waste factor and cost estimate.
Deck Calculator
Estimate decking materials, boards, screws, and cost for your deck project. Supports multiple board sizes.
Drywall Calculator
Calculate drywall sheets, joint compound, tape, and screws needed for your walls and ceilings.
Fence Calculator
Estimate posts, rails, pickets, and materials needed for your fence project with cost breakdown.
Grout Calculator
Calculate how much grout you need for tile installations based on tile size, spacing, and area.
Mulch Calculator
Calculate how much mulch you need for garden beds and landscaping. Results in cubic yards, bags, and cost.
Soil Calculator
Calculate soil volume needed for raised beds, gardens, and pots. Supports rectangle, circle, and custom shapes.
Wallpaper Calculator
Calculate how many rolls of wallpaper you need. Accounts for pattern repeats, doors, windows, and waste.
Body Fat Calculator
Estimate your body fat percentage using the US Navy method. Enter measurements to get your body composition.
Calorie Deficit Calculator
Calculate your calorie deficit for weight loss. Find your TDEE, target calories, and estimated timeline.
Heart Rate Zone Calculator
Calculate your heart rate training zones based on age and resting heart rate. Optimize cardio and fat burn.
Ovulation Calculator
Predict your ovulation date and fertile window based on your menstrual cycle length.
Pregnancy Due Date Calculator
Calculate your estimated due date based on last menstrual period or conception date. Track pregnancy milestones.
Water Intake Calculator
Calculate your recommended daily water intake based on weight, activity level, and climate.
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.