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100 tiny calculators for everyday questions
One small tool per question — from splitting a tip to sizing a subnet. Type what you need and get a number.
Percent of a NumberFind what X percent of any number is — 15% of 80, 7% of 249, anything.X Is What Percent of YWork out what percentage one number is of another.Percentage ChangeCalculate the percent increase or decrease between two values.Increase by a PercentageAdd a percentage on top of a number — price rises, raises, growth.Decrease by a PercentageReduce a number by a percentage and see what remains.Profit MarginGet margin percentage and profit from cost and revenue.MarkupCalculate markup percentage from cost and selling price.Discount PriceSee the final price after a percentage discount and how much you save.TipCalculate the tip and split the bill between any number of people.Percentage-Point DifferenceCompare two percentages the right way — points vs. relative change.
Add VATAdd VAT to a net price and see the gross amount and the tax.Remove VATExtract VAT from a gross price to find the net amount.Sales TaxAdd US-style sales tax to a sticker price.Gross to Net SalaryEstimate take-home pay from gross salary with a flat tax rate.Net to Gross SalaryFind the gross salary needed to hit a target take-home amount.Hourly ↔ Annual SalaryConvert between an hourly rate and annual, monthly and weekly pay.Loan Monthly PaymentMonthly payment for any amortized loan — car, personal, mortgage.Loan Total InterestSee how much interest a loan really costs over its full term.Mortgage OverpaymentSee how extra monthly payments cut interest and shorten a mortgage.Compound InterestGrow a lump sum with compounding and optional regular contributions.Simple InterestInterest that doesn't compound — flat rate on the original amount.Savings GoalHow many months of saving until you reach your target amount.Inflation-Adjusted ValueWhat today's money will really be worth after years of inflation.ROI (Return on Investment)Return on investment as a percentage of what you put in.CAGRCompound annual growth rate between a starting and ending value.
Hours ↔ Minutes ↔ SecondsConvert any time value between hours, minutes and seconds.Days Between DatesCount the days, weeks and months between any two dates.Add Days to a DateFind the date that's N days from any starting date — deadlines, returns, visas.Age from BirthdateExact age in years, months and days — plus days until the next birthday.Working Days Between DatesCount Monday–Friday business days between two dates.Minutes to Decimal HoursTurn hours and minutes into decimal hours for timesheets and payroll.Reading TimeEstimate how long a text takes to read from its word count.Download TimeHow long a file takes to download at a given connection speed.Playback Speed TimeHow long a video or podcast takes at 1.25×, 1.5×, 2× and custom speeds.Pomodoro Session PlannerPlan a pomodoro work session: total time, breaks, and when you'll finish.Time-Zone ShiftShift a clock time by a UTC-offset difference to plan calls across zones.Sleep Cycle BedtimeBest times to fall asleep so you wake at the end of a 90-minute cycle.
IPv4 SubnetFull subnet breakdown from an IP and CIDR prefix: network, broadcast, host range, mask.CIDR ↔ NetmaskConvert between a /prefix and a dotted netmask, either direction.Is IP in CIDR RangeCheck whether an IPv4 address falls inside a CIDR block.MAC Address FormatterReformat any MAC address into colon, dash, Cisco-dot or plain style.Data-Rate ConverterConvert between bps, Kbps, Mbps, Gbps and bytes-per-second rates.File Transfer TimeHow long moving a file takes over any link speed.Bandwidth-Delay ProductThe amount of data in flight on a link — sizes TCP windows correctly.RAID CapacityUsable space and fault tolerance for RAID 0, 1, 5, 6 and 10 arrays.Storage Units (KB ↔ KiB)Convert between decimal (KB, MB, GB) and binary (KiB, MiB, GiB) storage units.SLA Uptime → DowntimeHow much downtime 99.9%, 99.99% or any SLA actually allows.Hex ↔ Dec ↔ BinConvert numbers between hexadecimal, decimal and binary instantly.Video Bitrate → File SizeEstimate recording or stream size per hour from its bitrate.Ping RTT → DistanceRough physical distance implied by a ping time, at fiber light speed.DNS TTL HumanizerTurn TTL seconds into plain language and see common values.Common Port LookupWhat service lives on a well-known TCP/UDP port.
SHA-256 HashCompute the SHA-256 hash of any text, right in your browser.SHA-1 HashCompute the SHA-1 hash of any text — legacy but still everywhere.SHA-512 HashCompute the SHA-512 hash of any text, locally in your browser.MD5 HashCompute the MD5 hash of any text — for checksums and legacy systems.Bcrypt Hash & VerifyGenerate bcrypt password hashes and verify passwords against them.Password Strength & EntropyEntropy in bits and estimated crack time for any password.Password GeneratorCryptographically secure random passwords with a live entropy readout.Secure Random NumberA cryptographically secure random integer in any range.
Pixels → Print SizeHow large a photo can be printed at a given DPI, in cm and inches.Aspect-Ratio ResizeResize an image to a new width while keeping its aspect ratio.MegapixelsMegapixels, total pixel count and aspect ratio from a resolution.Uncompressed Bitmap SizeRaw in-memory size of an image from resolution and bit depth.Screen PPIPixel density of a display from its resolution and diagonal size.Video File SizeEstimate a video's file size from bitrate and duration.Retina Asset SizesThe @2x and @3x export sizes for any base (1x) asset.Letterbox BarsBlack-bar sizes when content of one aspect ratio plays on another screen.Image Grid LayoutRows, cell size and total height for an N-image grid.JPEG File-Size EstimateBallpark JPEG file size from megapixels and quality setting.
BMI (Body Mass Index)Body mass index from weight and height, with the WHO category.Daily Calorie NeedsBMR and maintenance calories with the Mifflin-St Jeor equation.Daily Water IntakeRecommended daily water from body weight and exercise time.Walking CaloriesCalories burned walking, from weight, duration and pace (MET formula).Body Fat % (US Navy)Body-fat percentage from tape measurements, US Navy method.Running PacePace per km and mile plus speed, from distance and finish time.Fuel Consumption ConverterConvert between L/100km, US MPG and UK MPG.Trip Fuel CostFuel needed and total cost for a road trip, with per-person split.Cooking Volume ConverterConvert cups, tablespoons, teaspoons, fluid ounces and milliliters.Recipe ScalerScale a recipe between serving counts and convert up to four amounts.
List StatisticsMean, median, min, max and sum of any list of numbers.Standard DeviationPopulation and sample standard deviation from a list of numbers.GCD & LCMGreatest common divisor and least common multiple of two integers.Quadratic EquationSolve ax² + bx + c = 0, including complex roots.Triangle AreaArea from base and height, or from three sides via Heron's formula.Circle Area & CircumferenceArea, circumference and diameter of a circle from its radius.Pythagorean TheoremFind the hypotenuse or a missing leg of a right triangle.Rule of ThreeSolve proportions: if A gives B, what does C give?Random IntegerA random whole number between any two bounds, inclusive.Roman NumeralsConvert numbers to Roman numerals and back, instantly.Base-N ConverterConvert numbers between any bases from 2 to 36.Temperature ConverterConvert between Celsius, Fahrenheit and Kelvin.Length ConverterConvert mm, cm, m, km, inches, feet, yards and miles.Weight ConverterConvert grams, kilograms, tonnes, ounces, pounds and stone.Area ConverterConvert m², km², hectares, acres and square feet.
Marketplace FeeYour net payout after a marketplace's percentage and fixed fees.Product Profit MarginProfit, margin and markup for a product from cost and selling price.Target Price from MarginThe selling price needed to hit a desired profit margin.Stacked DiscountsThe real combined discount when two percentages stack.Unit Price ComparisonCompare two pack sizes and see which is actually cheaper per unit.