Everyday & Conversions Calculators

The everyday shelf: calculators for questions that are not about money, health or homework

Some calculations do not belong to a profession. How long until the wedding, what the school run costs in petrol, what time 3pm in Denver is in London, whether that cable run is too long. This category collects those tools in one place: seven topic shelves covering time, the car, electrics, weather, science, school and a drawer of one-off converters. Every calculator is free, runs in your browser, and shows the working underneath the answer, so you can see how the result was reached rather than taking it on trust.

Time and date

The Time & Date shelf handles the arithmetic the calendar and the clock make awkward. The flagships are the Age Calculator, which works out an exact age in years, months and days by walking the calendar rather than dividing by 365.25, and the Date Calculator, which counts the days between dates and adds or subtracts days, weeks, months or years calendar-correctly. Around them sit the Day Counter for working-day totals, the Time Duration Calculator and Time Calculator for base-60 clock sums, the Hours Calculator and Time Card Calculator for timesheets and overtime, the Time Zone Calculator for meetings across zones, the Day of the Week Calculator for naming the weekday of any date from 1600 to 2400, and the Sleep Calculator for bedtimes built from whole 90-minute sleep cycles.

Driving and travel

The Driving & Travel shelf is about what the car actually costs and does. The Fuel Cost Calculator prices a trip from distance, economy and the pump price, with a per-person split for shared journeys, while the Gas Mileage Calculator measures your car's real economy from the odometer and the fuel you put in, in mpg (UK and US), L/100km and km/L at once. The Mileage Calculator turns business trips into a claim under HMRC, IRS or your own rate, the Tire Size Calculator reads a sidewall code into diameter and speedometer error when comparing sizes, and the Horsepower Calculator converts torque and RPM into power.

Electrics and tech

The Electrics & Tech shelf starts from the fundamentals: the Ohms Law Calculator derives voltage, current, resistance and power from any two of them with the formula named and substituted, the Resistor Calculator reads colour bands into values, and the Voltage Drop Calculator checks whether a cable run loses more than the usual guidance allows. On the household side, the Electricity Cost Calculator prices any appliance's running cost from its wattage and your unit rate. The networking pair, the Bandwidth Calculator and IP Subnet Calculator, cover download times (including the megabits-versus-megabytes trap) and subnet maths with the binary shown, and the Password Generator builds passwords and passphrases from your browser's own cryptographic randomness, with the entropy arithmetic alongside.

Weather

The Weather shelf answers one question three ways: what does it actually feel like out there? The Heat Index Calculator applies the official NWS formula for heat and humidity, the Wind Chill Calculator does the same for cold and wind, including frostbite-time context, and the Dew Point Calculator works out the temperature at which the air's moisture condenses, a better comfort measure than relative humidity on its own.

Science and units

The Science & Units shelf is the reference desk. The Conversion Calculator converts length, area, volume, mass, temperature, speed, time, storage, energy and pressure between any two units with the factor shown as working. Beside it sit the Speed Calculator for the distance-speed-time triangle, the Density Calculator with its floats-or-sinks verdict, the Mass Calculator for weight under different gravity, and the chemistry pair: the Molecular Weight Calculator, which reads a chemical formula into a molar mass, and the Molarity Calculator, which handles solution concentrations and dilutions and phrases the answer as a lab step.

School, sport and the handy drawer

The School & Sport shelf holds three specialists: the Grade Calculator works out your current weighted grade and the score you need on the final, the GPA Calculator turns credits and letter grades into a term or cumulative GPA, and the Golf Handicap Calculator follows the World Handicap System's own method from adjusted gross scores to a course handicap.

The Handy Tools shelf is the drawer of everything else, and it earns its keep. The Tip Calculator splits a restaurant bill with cash-friendly rounding, the Currency Calculator converts money at the rate you were quoted and exposes the hidden margin against the mid-market rate, and the Height Calculator predicts a child's adult height from the parents' heights by the mid-parental method. Alongside them: the Shoe Size Converter for UK, US and EU sizes, the Roman Numeral Converter for numbers from 1 to 3,999 with the working shown group by group, the Dice Roller with genuine cryptographic randomness and the odds behind every total, and the GDP Calculator for adding up an economy by spending or by income.

How the shelves work together on a real problem

Real problems rarely respect topic boundaries, which is why these tools share one address. Planning a trip abroad, the Fuel Cost Calculator prices the drive to the airport, the Time Zone Calculator sorts out when to call home, the Currency Calculator checks the exchange desk's margin, and the Tip Calculator handles the first restaurant bill. Sorting out a work rota, the Hours Calculator turns a week of clock-ins into hours worked and the Day Counter checks how many working days are left before a deadline. When a chain of everyday questions turns into a money question, the Money category picks up where this one stops, and when it turns into a materials or job-cost question, the Home & Garden category does the same.

Frequently asked questions

What belongs in the everyday category?

Anything practical that is not primarily a health, money or pure maths question: time and dates, driving costs, electrics, weather comfort, unit conversions, school grades and the odd one-off converter. If a tool's natural home is a kitchen table rather than an office, it lives here.

Do these calculators show their working?

Yes, that is the site's whole approach. Each one prints the formula it used and the substitution with your numbers, whether that is the base-60 carry in the Time Calculator, the frostbite-time context in the Wind Chill Calculator or the binary AND in the IP Subnet Calculator.

Which tools are the best place to start?

The most used shelf is Time & Date, and its flagships, the Age Calculator and Date Calculator, are good examples of how every tool on the site behaves. Material and job-cost questions, concrete, tiling, staircases and the rest, now live in the Home & Garden category.