How many everyday & Tech tools are there?

51: Age Calculator, Date Calculator, Day Counter, Day of the Week Calculator, Hours Calculator, Time Card Calculator, Time Duration Calculator, Tip Calculator and more. Each one shows the formula or rule it uses, so you can check the answer rather than trusting it.

Which everyday & Tech tool should I use first?

Age Calculator is the most used on the shelf: your exact age in years, months and days. Every tool works the same way, with inputs at the top and the working underneath the answer.

Is it free, and is my data stored?

Free and private. The calculation runs in your browser, so figures never leave your device, there is no account, and no calculation is logged.

Mondo Knows Tools

Free Everyday & Tech Calculators for Dates, Home, Cars & Units

The odds and ends of daily life: how many days until a date, how much concrete a slab needs, what a trip costs in fuel, or how to convert almost any unit. Free, instant, and explained so you are never guessing.

51 free tools on this shelf, all running in your browser

Age CalculatorYour exact age in years, months and days.Bandwidth CalculatorDownload time from file size and speed.Base64 Encode / DecodeConvert text to and from Base64.BTU CalculatorHeating or cooling capacity for a room.Concrete CalculatorCubic yards of concrete for a slab.Date CalculatorAdd or subtract days, weeks, months and years from a date.Day CounterDays between two dates, in every unit that matters.Day of the Week CalculatorWhich weekday any date falls on.Density CalculatorDensity, mass or volume, whichever is missing.Dew Point CalculatorThe temperature at which dew forms.Dice RollerRoll dice for games and decisions.Electricity Cost CalculatorWhat an appliance costs to run.Fuel Cost CalculatorWhat a trip costs in fuel.Gas Mileage CalculatorFuel economy from miles and gallons.GDP CalculatorGross domestic product from its spending parts.Golf Handicap CalculatorEstimated handicap index from recent rounds.GPA CalculatorWeighted GPA from your grades and credit hours.Grade CalculatorWhat you need on the final to hit your target grade.Gravel CalculatorTons of gravel for a driveway or bed.Heat Index CalculatorHow hot it feels with humidity.Height ConverterFeet and inches to centimetres, and back.Horsepower CalculatorHorsepower from torque and rpm, or from a quarter mile.Hours CalculatorHours worked between a start and end time.IP Subnet CalculatorNetwork, broadcast and host range from an IPv4 CIDR.Love CalculatorA bit of fun with two names.Molarity CalculatorMolar concentration from mass, molar mass and volume.Molecular Weight CalculatorMolar mass from a chemical formula.Mulch CalculatorBags or cubic yards of mulch for a bed.Ohms Law CalculatorVoltage, current, resistance and power from any two.Paint Coverage CalculatorHow much paint a room needs, in litres, gallons and cans.Password GeneratorStrong random passwords, generated in your browser.Recipe ScalerScale a recipe up or down and get the new amounts for every ingredient.Resistor Color Code CalculatorRead a 4-band resistor, or find the bands for a value.Roman Numeral ConverterConvert between numbers and Roman numerals.Roofing CalculatorRoofing squares and bundles from your footprint.Shoe Size ConverterConvert shoe sizes between US, UK, EU and cm.Sleep CalculatorBest bedtimes, wake times, or how much sleep you owe yourself.Speed CalculatorSpeed from distance and time.Square Footage CalculatorArea of a room or plot in square feet.Stair CalculatorRise, run and step count for a staircase.Tile CalculatorHow many tiles a floor or wall needs.Time Card CalculatorWeekly hours and pay from a simple timesheet.Time Duration CalculatorThe gap between two dates and times.Timezone Meeting PlannerFind a time that works in two cities, and see the overlap at a glance.Tip CalculatorTip and per-person total for a bill.Tire Size CalculatorCompare two tire sizes and the speedometer error.Unit ConverterLength, weight, volume, temperature and speed conversions.URL Encode / DecodePercent-encode or decode a URL or parameter.Voltage Drop CalculatorVoltage lost along a wire run.Weight ConverterPounds, kilograms, stones and ounces.Wind Chill CalculatorHow cold the wind makes it feel.

Questions people ask

How many everyday & Tech tools are there?: 51: Age Calculator, Date Calculator, Day Counter, Day of the Week Calculator, Hours Calculator, Time Card Calculator, Time Duration Calculator, Tip Calculator and more. Each one shows the formula or rule it uses, so you can check the answer rather than trusting it.
Which everyday & Tech tool should I use first?: Age Calculator is the most used on the shelf: your exact age in years, months and days. Every tool works the same way, with inputs at the top and the working underneath the answer.
Is it free, and is my data stored?: Free and private. The calculation runs in your browser, so figures never leave your device, there is no account, and no calculation is logged.