Calculators & Unit Converters
Quick, accurate calculators with the formula shown and a reference table on every page. Many are built around files and media: download times, video and photo storage, bitrate, DPI and pixel sizes. Others cover everyday maths, dates, money and unit conversions.
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Download Time CalculatorFind out how long a file, game or update will take to download at your internet speed.Video File Size CalculatorEstimate how big a video will be from its quality, bitrate and length.Photo Storage CalculatorCalculate how many photos fit on a phone, SD card or drive, for iPhone HEIC, phone JPG…Aspect Ratio CalculatorFind the aspect ratio of any resolution and calculate a new width or height that keeps…A4 Size in PixelsA4 is the standard paper size used everywhere except North America.Pixels to CentimetresConvert pixels to centimetres at any resolution: 96 DPI for screens, 300 DPI for print.Color ConverterConvert any colour between HEX, RGB, HSL and CMYK, with a live swatch and contrast ratios.Data Storage ConverterConvert between bits, bytes, KB, MB, GB, TB and the binary KiB, MiB, GiB and TiB.Percentage CalculatorWork out X% of a number, what percentage one number is of another, and percentage…Age CalculatorCalculate your exact age in years, months and days, plus total days and the countdown…Loan CalculatorCalculate the monthly payment, total interest and yearly repayment schedule for a…Compound Interest CalculatorSee how savings or investments grow with compound interest and regular monthly…Upload Time CalculatorEstimate how long it takes to upload videos, backups and large files at your upload speed.Video Bitrate CalculatorWork out the bitrate to export at so a video fits a size limit, like Discord's or an…Audio File Size CalculatorSee how much space an MP3, AAC, WAV or FLAC recording takes per minute and per hour.Image File Size CalculatorEstimate the size of an image from its pixel dimensions and colour depth.Video Storage CalculatorCalculate recording time for 1080p and 4K video on phones, SD cards, drives and cameras.Print Size CalculatorFind out how large an image prints at 300 DPI (photo quality) or any other resolution.PPI CalculatorCalculate the pixel density (PPI) and dot pitch of any monitor, laptop or phone screen.Megapixel CalculatorConvert pixel dimensions to megapixels and see how large the image can be printed.Paper Size in PixelsGet the exact pixel dimensions of A0–A6, Letter, Legal and photo sizes at any DPI.A3 Size in PixelsA3 is twice the size of A4, common for posters and drawings.Letter Size in PixelsLetter is the standard paper size in the US and Canada (8.5 × 11 in).Centimetres to PixelsConvert centimetres to pixels at any resolution: 96 DPI for screens, 300 DPI for print.Pixels to InchesConvert pixels to inches at any resolution: 96 DPI for screens, 300 DPI for print.Inches to PixelsConvert inches to pixels at any resolution: 96 DPI for screens, 300 DPI for print.Pixels to MillimetresConvert pixels to millimetres at any resolution: 96 DPI for screens, 300 DPI for print.Millimetres to PixelsConvert millimetres to pixels at any resolution: 96 DPI for screens, 300 DPI for print.PX to PTConvert font sizes between px and pt for CSS, Word and design tools.PT to PXConvert font sizes between pt and px for CSS, Word and design tools.PX to REMConvert font sizes between px and rem for CSS, Word and design tools.REM to PXConvert font sizes between rem and px for CSS, Word and design tools.HEX to RGBTurn a hex colour code into RGB, HSL and CMYK values.RGB to HEXTurn RGB values into a hex colour code for CSS and design tools.Unix Timestamp ConverterConvert Unix epoch timestamps (seconds or milliseconds) to dates, and dates to timestamps.Kilobytes to Megabytes1 KB = 0.001 MB.Megabytes to Kilobytes1 MB = 1,000 KB.Megabytes to Gigabytes1 MB = 0.001 GB.Gigabytes to Megabytes1 GB = 1,000 MB.Gigabytes to Terabytes1 GB = 0.001 TB.Terabytes to Gigabytes1 TB = 1,000 GB.Bytes to Kilobytes1 B = 0.001 KB.Gigabytes to Gibibytes1 GB = 0.93132257 GiB.Mbps to MB/s1 Mb = 0.125 MB.Centimetres to Inches1 cm = 0.39370079 in.Inches to Centimetres1 in = 2.54 cm.Feet to Metres1 ft = 0.3048 m.Metres to Feet1 m = 3.2808399 ft.Kilometres to Miles1 km = 0.62137119 mi.Miles to Kilometres1 mi = 1.609344 km.Millimetres to Inches1 mm = 0.03937008 in.Inches to Millimetres1 in = 25.4 mm.Kilograms to Pounds1 kg = 2.20462262 lb.Pounds to Kilograms1 lb = 0.45359237 kg.Grams to Ounces1 g = 0.03527396 oz.Ounces to Grams1 oz = 28.34952313 g.Celsius to Fahrenheit°F = °C × 9/5 + 32.Fahrenheit to Celsius°C = (°F − 32) × 5/9.Litres to Gallons1 l = 0.26417205 gal.Millilitres to Fluid ounces1 ml = 0.03381402 fl oz.Kilometres per hour to Miles per hour1 km/h = 0.62137119 mph.Miles per hour to Kilometres per hour1 mph = 1.609344 km/h.Length ConverterConvert metres, centimetres, inches, feet, yards, kilometres and miles.Weight ConverterConvert kilograms, grams, pounds, ounces, stone and tonnes.Temperature ConverterConvert Celsius, Fahrenheit and Kelvin.Area ConverterConvert square metres, square feet, acres, hectares and more.Volume ConverterConvert litres, millilitres, gallons, cups, fluid ounces and spoons.Speed ConverterConvert km/h, mph, metres per second, knots and feet per second.Time ConverterConvert milliseconds, seconds, minutes, hours, days, weeks, months and years.Percentage Change CalculatorCalculate the percentage increase or decrease from one value to another.Discount CalculatorFind the sale price after a percentage discount, stacked discounts and sales tax.Tip CalculatorWork out the tip and split the bill between any number of people.Sales Tax CalculatorAdd sales tax to a net price, or remove it from a gross price.VAT CalculatorAdd VAT to a net price, or remove it from a gross price.Days Between DatesCount the days, weeks, months and working days between two dates.Add Days to a DateFind the date a number of days, weeks, months, years or working days from a given date.Hours CalculatorCalculate the hours and minutes between two times, minus breaks, including overnight…BMI CalculatorCalculate your body mass index in kg/cm or lb/ft and see the healthy weight range for…Calorie CalculatorEstimate the calories you burn each day (TDEE) and targets for losing or gaining weight.Simple Interest CalculatorCalculate simple interest and the total amount from principal, rate and time.Salary CalculatorConvert pay between hourly, daily, weekly, monthly and yearly amounts.Average CalculatorPaste a list of numbers to get the mean, median, mode, range and standard deviation.Fuel Cost CalculatorWork out what a trip costs in fuel, in km or miles, with MPG, L/100 km or km/L.Reading Time CalculatorEstimate how long a text takes to read silently or to say out loud in a speech.
About the Calculators & Unit Converters
Every calculator here updates as you type and keeps your numbers in the page address, so you can bookmark a result or send it to someone. Each page also explains the formula and includes a reference table of common values, so you can check an answer at a glance.
The file and media calculators are the ones you won't find on a general calculator site: how long a download will take, how big a video will be, which bitrate fits under 25 MB, how many photos fit on 128 GB, and how many pixels A4 is at 300 DPI.
Common questions
Are these calculators accurate?
They use standard formulas and exact conversion factors. Real-world results like download times and file sizes vary, so those pages also show typical ranges.
Why does my 1 TB drive show 931 GB?
Drive makers use decimal units (1 TB = 1,000,000,000,000 bytes); Windows reports binary units (1 GiB = 1,073,741,824 bytes). Use the data storage converter's GB and GiB options to compare.
Can I share a result?
Yes. The page address updates with your inputs: copy the link and the calculator opens with the same numbers.