Free online calculators

Calculate your exact age from date of birth in years, months and days. Free online age calculator with total days, weeks and next birthday countdown.

Calculate your BMI with this free online BMI calculator in kg/cm or lb/ft-in. See your WHO or Asian BMI category and the healthy weight range for your height.

Calculate percentages with this free online percentage calculator: X% of Y, what percent X is of Y, percent increase or decrease and percent difference.

Calculate the age difference between two people in years, months and days with this free online age difference calculator. Includes the half-plus-seven rule.

Calculate UK alcohol units, US standard drinks and grams of alcohol with this free online alcohol unit calculator, and compare to the weekly guideline.

Find the traditional and modern wedding anniversary gift, gemstone, and flower for any year instantly with this free online anniversary gift finder.

Calculate the aspect ratio of any width and height, or resize to a new size with the same ratio. Free online aspect ratio calculator for 16:9, 4:3 and 9:16.

Calculate the average of any list of numbers, plus median, mode, range and sum, or a weighted average. Free online average calculator with steps shown.

Estimate blood alcohol content with this free online BAC calculator: add drinks, weight and time to see your BAC, time until sober and legal limits.

Add, subtract, multiply and divide binary numbers with this free online binary calculator, plus AND, OR, XOR and bit shifts with hex, octal and decimal results.

Estimate your blood alcohol content (BAC) from drinks, weight and time with this free online BAC calculator. See when you will be back to zero.

Calculate your body fat percentage online free with the U.S. Navy tape method in cm or inches. Free online body fat calculator with lean mass and ACE chart.

Calculate your bra size from underbust and bust measurements with this free online bra size calculator. Get US, UK, EU, French and Australian sizes.

Calculate the BTU you need to cool a room with this free online BTU calculator. Size an air conditioner by room area, ceiling height, sun and occupants.

Calculate your daily caffeine intake from coffee, tea, soda and energy drinks with this free online caffeine calculator. See how much remains at bedtime.

Calculate how many calories you need per day to maintain, lose or gain weight. Free online calorie and TDEE calculator with BMR and macro breakdown.

Calculate calories burned walking, running, cycling, swimming and 30+ activities by weight and time with this free online calories burned calculator.

Calculate how much carpet you need with this free online carpet calculator. Get square yards or square metres with waste, roll length and total cost.

Convert cat years to human years with the vet age formula and AAFP/ICatCare life stage. Free online cat age calculator, indoor vs outdoor lifespan.

Calculate your Chinese age (xusui) from your birthday with real Lunar New Year dates. Free online tool that also shows your Korean age and zodiac animal.

Find your Chinese zodiac animal, element and yin/yang from your exact birth date. Free online calculator with best matches, lucky numbers and colors.

Calculate a circle's area, circumference, diameter and radius from any one value. Free online circle calculator with the formulas A = πr² and C = 2πr.

Calculate your conception date from your due date, last period or birth date with this free online conception calculator. See the likely date range.

Calculate how many concrete blocks you need for a wall with this free online concrete block calculator. Get courses, mortar bags, waste and total block cost.

Calculate how much concrete you need for a slab, footing or column with this free online concrete calculator, in cubic yards or m³ plus 80, 60 or 40 lb bags.

Convert cups to grams for flour, sugar, butter and 20+ baking ingredients with this free online cups to grams converter. Also tbsp, tsp, ml and grams to cups.

Calculate the days between two dates or add and subtract days, weeks, months or years from a date. Free online date calculator with business days.

Calculate deck boards, joists, beams, posts and screws with this free online deck calculator. Enter deck size and board width for a full material list.

Calculate the dew point from temperature and humidity with this free online dew point calculator. Also find relative humidity and how humid it feels.

Calculate the sale price and how much you save online free. Free online discount calculator for % off, stacked extra discounts, sales tax and original price.

Calculate how much to feed your dog with this free online dog food calculator. Uses weight, life stage and food calories to give cups or grams per day.

Convert dog years to human years by size with the vet age chart and the new DNA formula. Free online dog age calculator with life stage for any breed size.

Calculate how many drywall sheets you need with this free online drywall calculator. Includes ceilings, doors, windows, waste, tape, mud and screws.

Calculate what an appliance costs to run per day, month and year with this free online electricity cost calculator from its watts, hours and price per kWh.

Calculate powers and exponents with this free online exponent calculator: exact big numbers like 2^100, negative exponents as fractions and fractional powers.

Calculate fence posts, rails, pickets or panels and concrete bags with this free online fence calculator. Supports privacy, picket and panel fences.

Calculate what you need on your final exam with this free online final grade calculator. Enter current grade, target and exam weight to see your score.

Calculate how much flooring you need with this free online flooring calculator. Add rooms, waste for the lay pattern and box coverage to get boxes and cost.

Add, subtract, multiply and divide fractions and mixed numbers online free with steps. Free online fraction calculator that simplifies and converts decimals.

Calculate the gas cost of a trip online free from distance, MPG or L/100 km and fuel price. Free online fuel cost calculator with round trip, split and MPG.

Calculate your GPA online free on the 4.0 scale: semester, weighted (Honors/AP) and cumulative GPA with credit hours. Free online GPA calculator.

Calculate your weighted class grade online free and find what you need on your final exam. Free online grade calculator with letter grades and test scores.

Curve test scores with this free online grade curve calculator. Raise the top score to 100, shift to a target average or use a square root curve.

Calculate how much gravel, stone, sand, topsoil or mulch you need with this free online gravel calculator, in cubic yards, tons, m³ or bags.

Calculate the remaining amount, half-life or elapsed time with this free online half-life calculator. Includes caffeine and carbon-14 presets and a decay table.

Calculate the heat index (feels-like temperature) with this free online calculator. Enter temperature and humidity to see the NWS heat danger level.

Predict how tall your child will be as an adult from both parents' heights with this free online height predictor, with a likely range in cm or feet.

Calculate hours worked online free from clock-in and clock-out times with breaks. Free online time card calculator with decimal hours, overtime and pay.

Calculate your ideal body weight with this free online ideal weight calculator using the Robinson, Miller, Devine and Hamwi formulas plus the healthy BMI range.

Find the least common multiple (LCM) and greatest common factor (GCF) of two or more numbers with this free online calculator, with prime factorization.

Calculate your life path number from your birth date with step-by-step math. Free online numerology tool with master numbers, meanings and your personal year.

Calculate logarithms in any base with this free online log calculator: log base 10, natural log (ln), log base 2, antilog and change of base.

Solve long division step by step with the full written working, remainders or decimal answers and repeating decimals. Free online long division calculator.

Calculate your love percentage with any name using this free online love calculator, or play the classic FLAMES game and share the result with your crush.

Calculate your daily macros for weight loss, maintenance or muscle gain with this free online macro calculator. Get protein, fat and carb grams instantly.

Calculate matrix determinant, inverse, RREF, rank, multiplication and powers with exact fractions and row-operation steps. Free online matrix calculator.

Calculate molar mass (molecular weight) of any chemical formula with this free online molar mass calculator — element breakdown, mass percent, grams to moles.

Calculate your moon sign from your birth date, time and time zone with precise lunar math. Free online moon sign calculator that also shows your sun sign.

Calculate your car's gas mileage in MPG, L/100 km and km/L with this free online MPG calculator. Enter distance and fuel used to get fuel economy and cost.

Calculate how much mulch you need in cubic yards and bags with this free online calculator. Enter your bed size and depth to estimate bags and cost.

See a multiplication table chart up to 20 × 20 and practise times tables 1–12 with a free online quiz — score, streaks and missed facts to review.

Calculate voltage, current, resistance and power with this free online Ohm's law calculator — enter any two values and get the other two in mA, kΩ or kW.

Calculate your one rep max (1RM) from any set with this free online one rep max calculator — 7 formulas averaged, plus a 50–100% training weight table.

Calculate your ovulation day and fertile window online free from your last period and cycle length. Free online ovulation calculator for the next cycles.

Calculate your running pace, finish time or distance online free in km or miles. Free online pace calculator with 5K to marathon predictions and splits.

Calculate how much paint you need for a room with this free online paint calculator: walls, ceiling, doors, windows and coats, in gallons or liters.

Calculate percent error between a measured and true value with this free online percent error calculator, plus percent difference and percent change.

Calculate your next period, fertile window and ovulation day for the coming months with this free online period calculator and add them to your calendar.

Calculate permutations (nPr) and combinations (nCr), with or without repetition, and list every arrangement. Free online calculator with formulas shown.

Calculate pizza dough with this free online pizza dough calculator. Set pizzas, ball weight, hydration, salt and yeast to get exact baker's percentages.

Calculate your age on Mercury, Venus, Mars, Jupiter and other planets from your birthday. Free online space age calculator with your next planet birthdays.

Calculate how many gallons or litres are in your pool with this free online pool volume calculator. Works for rectangle, round and oval pools.

Calculate your pregnancy due date with this free online pregnancy calculator from your last period, conception, IVF transfer or an ultrasound scan.

Calculate healthy pregnancy weight gain by week from your pre-pregnancy BMI with this free online pregnancy weight gain calculator, for one baby or twins.

Find the prime factorization of any number with steps, check if a number is prime, list all divisors and prime numbers. Free online prime factor calculator.

Calculate how much protein you need per day with this free online protein calculator — by weight, goal and activity, with per-meal grams and food examples.

Estimate how big your puppy will get with this free online puppy weight calculator — enter age, current weight and breed size to predict adult weight.

Find the missing side of a right triangle with this free online Pythagorean theorem calculator, plus angles, area, perimeter and exact square-root answers.

Solve ax² + bx + c = 0 with step-by-step working: discriminant, real or complex roots, vertex and axis of symmetry. Free online quadratic formula calculator.

Solve ratios and proportions (A:B = C:?), simplify ratios like 12:18 or 1.5:2.25, and split an amount in a ratio with this free online ratio calculator.

Scale any recipe up or down with this free online recipe scaler. Paste your ingredients, set servings or a factor, and get clean, kitchen-friendly amounts.

Get a lucky, auspicious red envelope amount suggestion by region, occasion, and recipient with this free online hongbao calculator.

Convert ring sizes between US, UK, EU and Japan, or find your size from finger circumference, with this free online ring size converter and size chart.

Calculate your rising sign (ascendant) from your birth date, time and city. Free online calculator showing your big three: sun, moon and rising signs.

Calculate roof area, roofing squares and shingle bundles with this free online roofing calculator. Includes roof pitch, overhang, waste and underlayment.

Round numbers to the nearest whole, tenth, hundredth, ten or thousand, with the reason shown. Free online rounding calculator with banker's rounding too.

Use a free online scientific calculator with sin, cos, tan, log, ln, powers, roots, factorial and π. Degrees or radians, keyboard input and calculation history.

Convert numbers to scientific notation and back with this free online converter. Get decimal, E-notation and engineering notation, and round to sig figs.

Convert shoe sizes between US, UK and EU for men and women, or find your size from foot length, with this free online shoe size converter and chart.

Count significant figures and round to any number of sig figs with this free online sig fig calculator, with decimal, scientific and E-notation results.

Calculate the best time to go to bed or wake up online free using 90-minute sleep cycles. Free online sleep calculator and bedtime planner for all ages.

Calculate your sleep debt from the last 7 nights with this free online sleep debt calculator and get a gradual recovery plan for the coming nights.

Find the slope between two points as a fraction and decimal, plus the line equation y = mx + b, distance, midpoint and angle. Free online slope calculator.

Calculate how many solar panels you need with this free online solar panel calculator. Get system size, annual output, roof area, savings and payback.

Calculate speed, distance or time from the other two with this free online speed distance time calculator — km/h, mph, m/s and knots, plus pace per km/mile.

Calculate square footage online free for rooms, floors and yards in feet, inches, meters or yards. Free online square feet calculator with waste and cost.

Calculate square roots, cube roots and any nth root with this free online square root calculator, with simplified radical form like √72 = 6√2.

Calculate stair steps, riser height, tread depth, stringer length and angle with this free online stair calculator, including building code checks.

Calculate standard deviation, variance, mean, median, mode and quartiles online free. Free online standard deviation calculator for sample or population data.

Convert steps to miles and kilometres based on your height with this free online steps to miles converter. See stride length, steps per mile and calories.

Calculate your target heart rate and 5 training zones by age with this free online target heart rate calculator — max HR, Karvonen method and fat-burning zone.

Calculate your TDEE (total daily energy expenditure) with this free online calculator. Get maintenance calories plus targets to lose or gain weight.

Calculate how many tiles you need for a floor or wall with this free online tile calculator. Includes grout gap, waste allowance, boxes and total cost.

Calculate total time by adding or subtracting hours, minutes and seconds, or find the time after a duration with this free online time calculator.

Calculate weekly work hours with this free online time card calculator. Enter clock-in, clock-out and breaks to get total hours, overtime and gross pay.

Calculate the tip and split the bill online free. Free online tip calculator with 15%, 18%, 20% presets, per-person totals, pre-tax tipping and round up.

Compare tire sizes online free: diameter, sidewall, width, revolutions per mile and speedometer error. Free online tire size calculator, metric and flotation.

Calculate turkey cooking time by weight, stuffed or unstuffed, plus thawing days and when to start the oven with this free online turkey calculator.

Find the ideal TV size for your room or the best viewing distance for a screen you own. Free online TV size calculator with SMPTE, THX and 4K/8K presets.

Calculate the volume of a cube, box, cylinder, sphere, cone, pyramid and more with this free online volume calculator — in litres, gallons, m³ and ft³.

Calculate your waist-to-hip ratio with this free online WHR calculator. See your health-risk band for men or women, plus waist-to-height ratio in cm or inches.

Calculate how many rolls of wallpaper you need with this free online calculator. Enter room size, doors, windows and pattern repeat for an exact roll count.

Calculate how much water to drink a day with this free online water intake calculator, based on weight, exercise and climate, plus a daily glass tracker.

Calculate the wind chill (feels-like temperature) with this free online calculator. Enter temperature and wind speed to see the frostbite risk and time.

Calculate z-scores, percentiles and normal probabilities, or the z for a probability like 95%, with this free online z-score calculator and bell curve.

Calculate zodiac compatibility for two star signs or birthdays. Free online love and friendship score with element and modality reasons and a shareable card.

Find your zodiac sign from your birthday with this free online zodiac sign calculator — star sign, element, traits, Chinese zodiac animal and birthstone.