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Free calculators and everyday tools. Press play and watch every number get calculated, step by step. No sign-up, no clutter.
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Tide Calculator
Pick a coastal station and a date to see NOAA's predicted high and low tide times and heights for that day, the tidal range between them, and whether the Moon phase points to a bigger spring tide or a smaller neap tide.
BMI Calculator
BMI is your weight in kilograms divided by your height in metres squared. A 70 kg adult who is 1.70 m tall has a BMI of 24.2, which is in the healthy range of 18.5 to 24.9.
Percentage Calculator
To find a percentage of a number, divide the percent by 100 and multiply by the number: 15% of 200 is 0.15 ร 200 = 30.
Age Calculator
Your age is the number of complete years, months and days between your date of birth and today. Someone born on 15 May 1990 is 36 years, 4 months and 6 days old on 21 September 2026.
Loan & Mortgage Calculator
A $300,000 loan at 6.5% over 30 years costs about $1,896 a month, and roughly $382,600 of that total is interest.
Unit Converter
Pick a type, enter a value and choose the units. For example, 1 mile is 1.609 kilometres, 1 kilogram is 2.205 pounds and 1 US gallon is 3.785 litres.
Tip Calculator & Bill Splitter
To calculate a tip, multiply the bill by the tip percent as a decimal. An 18% tip on a $50 bill is 0.18 ร 50 = $9, for a total of $59. Split three ways, that is $19.67 each.
Calorie Calculator (TDEE)
Your daily calorie need is your basal metabolic rate (BMR) multiplied by an activity factor. For a 30-year-old man who is 180 cm, weighs 80 kg and exercises 3 to 5 days a week, that is about 2,760 calories a day.
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Calculators
See all โOnline Calculator with Steps
Type an expression like 12 ร (3 + 4) รท 2 + 5 and press =. It follows the order of operations (brackets, powers, multiply and divide, then add and subtract) and animates each step until only the answer is left.
Pregnancy Due Date Calculator
Your estimated due date is 280 days (40 weeks) after the first day of your last period. For example, a last period starting March 1 gives a due date of about December 6.
BMI Calculator
BMI is your weight in kilograms divided by your height in metres squared. A 70 kg adult who is 1.70 m tall has a BMI of 24.2, which is in the healthy range of 18.5 to 24.9.
Calorie Calculator (TDEE)
Your daily calorie need is your basal metabolic rate (BMR) multiplied by an activity factor. For a 30-year-old man who is 180 cm, weighs 80 kg and exercises 3 to 5 days a week, that is about 2,760 calories a day.
Ovulation Calculator
Ovulation usually happens about 14 days before your next period starts. In a 28-day cycle that is cycle day 14, and your most fertile days are the five days before it plus ovulation day itself.
Body Fat Calculator
The US Navy method estimates body fat from your neck, waist and (for women) hip measurements, using a formula built from log-scaled circumference differences. A 32-inch waist and 15-inch neck at 5'8" puts a man at roughly 14โ15% body fat, in the athletic-to-fitness range.
Macro Calculator
Multiply your daily calorie target by each macro's percentage, then divide by its calories per gram: protein and carbs are 4 kcal/g, fat is 9 kcal/g. On a 2,000-calorie, 30/40/30 split, that's 150 g protein, 200 g carbs and 67 g fat.
One-Rep Max Calculator
Your estimated one-rep max is the weight you lifted ร (1 + reps รท 30). Lifting 100 kg for 5 reps gives an estimated 1RM of about 116.7 kg.
Water Intake Calculator
A common baseline is 30โ35 ml of water per kilogram of body weight per day, plus more for exercise and hot weather. A 70 kg adult with 30 minutes of exercise in a temperate climate needs roughly 2.8 litres a day.
Ideal Weight Calculator
The Devine formula estimates ideal weight from height alone: 50 kg (men) or 45.5 kg (women) at 5 feet tall, plus 2.3 kg for every inch above that. At 175 cm, that's about 68.9 kg for a man.
Heart Rate Zone Calculator
Using the Karvonen method, your target zones are based on your heart rate reserve โ the gap between your estimated max heart rate (220 minus your age) and your resting heart rate.
Temperature Converter (ยฐC, ยฐF, K)
To convert Celsius to Fahrenheit, multiply by 9/5 (1.8) and add 32: 20 ยฐC is 68 ยฐF. To convert Fahrenheit to Celsius, subtract 32 and multiply by 5/9.
Heat Index Calculator
The heat index combines air temperature and humidity to show how hot it feels. At 90 ยฐF (32 ยฐC) and 70% humidity it feels like about 106 ยฐF (41 ยฐC), which is in the Danger range.
Wind Chill Calculator
Wind chill shows how cold the wind makes exposed skin feel. At 20 ยฐF (โ7 ยฐC) with a 15 mph (24 km/h) wind it feels like about 6 ยฐF (โ14 ยฐC).
Dew Point Calculator
The dew point is the temperature at which air becomes saturated and dew forms. At 25 ยฐC (77 ยฐF) and 60% humidity the dew point is about 16.7 ยฐC (62 ยฐF), which feels slightly humid.
Frost Date Calculator
Pick your nearest city to see the typical date of the last spring frost, the first fall frost, and how many frost-free days usually fall in between โ plus, if you enter a date, the estimated chance frost still lands on it.
Sunrise & Sunset Calculator
Sunrise and sunset times depend on your latitude, longitude and the date. In London on the June solstice the sun rises at about 4:43 AM and sets at about 9:21 PM, giving roughly 16 hours 38 minutes of daylight.
Wind Speed Converter & Beaufort Scale
To convert m/s to km/h, multiply by 3.6. To convert km/h to mph, multiply by 0.6214. A 10 m/s wind is 36 km/h, 22.4 mph or 19.4 knots, which is Force 5 (a fresh breeze) on the Beaufort scale.
Absolute Humidity Calculator
Absolute humidity is the mass of water vapour in each cubic metre of air. At 20 ยฐC and 50% relative humidity, air holds about 8.6 g of water per mยณ, half of the 17.3 g/mยณ it could hold when saturated.
Rainfall Converter & Rain Volume Calculator
One millimetre of rain over one square metre is exactly one litre. One inch of rain is 25.4 mm, and over one acre it is about 27,154 US gallons (102,790 litres).
Moon Phase Calculator
Enter any date to see the Moon's phase, how much of it is illuminated, and how many days until the next full and new moons โ worked out from how many days have passed since a known new moon, divided by the Moon's roughly 29.53-day cycle.
Tide Calculator
Pick a coastal station and a date to see NOAA's predicted high and low tide times and heights for that day, the tidal range between them, and whether the Moon phase points to a bigger spring tide or a smaller neap tide.
Age Calculator
Your age is the number of complete years, months and days between your date of birth and today. Someone born on 15 May 1990 is 36 years, 4 months and 6 days old on 21 September 2026.
Days Between Dates Calculator
Subtract the earlier date from the later one to get the days between them. From 1 January to 25 December 2026 is 358 days, or 359 if you count both the first and last day.
Time Zone Calculator & World Clock
Pick a base city and a date and time, then pick a second city to compare it to. You'll instantly see the equivalent local time there, how many hours ahead or behind it is, and whether that puts it on a different calendar day.
Unit Converter
Pick a type, enter a value and choose the units. For example, 1 mile is 1.609 kilometres, 1 kilogram is 2.205 pounds and 1 US gallon is 3.785 litres.
Area Calculator & Size Comparison
Enter an area and a unit, and instantly see how many football pitches, tennis courts or parking spaces it's equivalent to, alongside the exact conversion between area units.
Tip Calculator & Bill Splitter
To calculate a tip, multiply the bill by the tip percent as a decimal. An 18% tip on a $50 bill is 0.18 ร 50 = $9, for a total of $59. Split three ways, that is $19.67 each.
GPA Calculator
GPA is the total grade points across your courses (each grade's point value ร its credit hours) divided by your total credit hours. Three courses graded A, B+ and B at 3, 3 and 4 credits work out to a 3.33 GPA.
Final Grade Calculator
Your overall grade is each category's score multiplied by its share of the total weight, added together. Leave one category blank โ like a final exam โ and enter a target grade instead, and the calculator solves for the score that category needs.
Time Duration Calculator
To find the time between two clock times, convert both to minutes past midnight and subtract. From 9:00 AM to 5:30 PM is 8 hours 30 minutes.
Fraction Calculator
To add or subtract fractions, first convert them to a common denominator. To multiply, multiply straight across. To divide, multiply by the second fraction flipped upside down. This calculator shows every step and simplifies the result.
Roman Numeral Converter
Roman numerals are built from I (1), V (5), X (10), L (50), C (100), D (500) and M (1000), taking the largest values first โ 1994 becomes MCMXCIV (1000 + 900 + 90 + 4).
Electrical Calculator (Volts, Amps, Watts, Ohms)
Enter any two of voltage (V), current (A), power (W) or resistance (ฮฉ) and the calculator finds the other two using Ohm's law (V = I ร R) and Watt's law (P = V ร I). A 120 V circuit drawing 10 A is using 1,200 W.
Electricity Cost Calculator
Multiply the appliance's kilowatts by the hours used and by your electricity rate to get the cost. A 1,500 W heater run 2 hours a day at $0.16 per kWh costs about $0.48 a day, or roughly $14.40 a month.
Power Load Calculator
Add up each appliance's watts to find your running load, add headroom for the largest motor starting up to size a generator, project your daily energy use into a monthly usage and cost, and multiply it by how many backup days you want to size a battery bank or solar array.
Fuel Cost Calculator
Trip cost = distance รท fuel efficiency ร fuel price. A 300-mile trip at 30 mpg with fuel at $3.50 a gallon costs about $35.
Percentage Calculator
To find a percentage of a number, divide the percent by 100 and multiply by the number: 15% of 200 is 0.15 ร 200 = 30.
Compound Interest Calculator
Compound interest means you earn interest on your interest. $10,000 at 7% for 20 years with no deposits grows to about $40,400 with monthly compounding.
Loan & Mortgage Calculator
A $300,000 loan at 6.5% over 30 years costs about $1,896 a month, and roughly $382,600 of that total is interest.
Savings Goal Calculator
To hit a savings goal, this calculator works backwards from compound interest: enter your goal, starting balance, interest rate and either a deadline (to find the monthly deposit needed) or a monthly deposit (to find how long it will take).
Currency Converter
Enter an amount and a currency, and see it converted into a dozen major world currencies at once, using the latest official exchange rates โ updated daily from the European Central Bank.
Tools
See all โQR Code Generator
Type or paste a link or text, pick your colours, and download the QR code as a PNG or SVG. It is generated in your browser and nothing is uploaded.
vCard QR Code Generator
Fill in a name, phone number and email, and this tool builds a QR code that a phone's camera app recognises as a contact card โ scanning it offers to add the person straight to Contacts, no app or typing required.
Barcode Generator
Choose a format, enter your number or text, and download the barcode. Code 128 accepts most text; EAN-13 and UPC-A need exactly 12 or 11 digits plus an automatic check digit.
Password & Passphrase Generator
A strong password is long and random: 16 or more characters mixing letters, numbers and symbols. For something you must remember, use a passphrase of 5 or more random words. Both are generated in your browser using your device's secure random source and never sent anywhere.
Word & Character Counter
Paste or type your text to see live counts of words, characters, sentences and paragraphs, plus how long it takes to read or read aloud at an average pace.
Case Converter
Type or paste your text once to see it converted into ten common cases at the same time โ from Title Case for headings to camelCase and snake_case for code โ and copy any one with a single click.
Typing Speed Test
Type the passage shown to see your speed in words per minute and your accuracy update live, with a colour-coded keyboard showing exactly which finger to use for each key as you go.
Random Number Generator
Set a minimum, a maximum and how many numbers you want, then press Generate. Numbers are produced in your browser using a cryptographically secure random source, the same kind used for encryption.
Lorem Ipsum Generator
Choose paragraphs, sentences or words and how many you need, then copy the generated placeholder text straight into your design or document.
Unix Timestamp Converter
A Unix timestamp counts seconds (or milliseconds) since midnight UTC on January 1, 1970. Enter a timestamp to see its date, or pick a date to get its timestamp.
Color Converter
Pick a color, or type a hex code, RGB values or HSL values โ all three formats update together instantly, each with its own copy button.
Guides
See all โThe Nitrogen Cycle, Explained for Gardeners
Nitrogen moves through five stages in a garden: bacteria fix nitrogen gas from the air into ammonium, other bacteria convert that to nitrate, plants absorb it, decomposers return it to the soil when plants and animals die, and denitrifying bacteria release some of it back into the air โ completing the cycle.
Tomato Growth Stages: Seed to Harvest
A tomato seed sprouts in 5โ10 days in warm soil, then takes roughly 100โ120 days from sowing (60โ85 days after transplanting) to reach a ripe, harvestable fruit, passing through seedling, vegetative growth, flowering and fruit-ripening stages along the way.
Carrot Growth Stages: Seed to Harvest
Carrot seeds are unusually slow to germinate, typically taking 14โ21 days, then the root spends 60โ80 days total bulking up underground before it's ready to harvest โ most of that growth is invisible from above ground.
Radish Growth Stages: Seed to Harvest
Radishes are the fastest common vegetable to grow: seeds sprout in just 3โ5 days, and most varieties are ready to pull in as little as 21โ30 days from sowing.
See every step
Each calculator can replay its own working, so you understand the answer and not just the number.
Private by design
QR, barcode and password tools run in your browser. Nothing you type is uploaded.
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