Online Calculators & Tools

Turns a fasting protocol and one meal time into clock times: when the eating window opens and closes, when the fast ends, and the halfway point.

Works out a heating and cooling load from the building envelope itself: wall and ceiling areas, R-values, window U-values, air changes, solar gain and internal gains.

Adds, subtracts, multiplies and divides hexadecimal numbers, and runs AND, OR, XOR, NOT and the shifts, with every answer given in hex, decimal and binary.

Daily calorie needs from the revised 1984 Harris-Benedict equations, with the original 1919 figures and Mifflin-St Jeor shown beside them.

Works out how much hardwood a floor takes: the square footage, the waste allowance, the number of boxes to buy and the board and row count.

Prices a hardwood floor installed: boards plus waste, labour, sanding and finishing, fasteners, underlayment, removing the old floor and the trim.

Finds the date six calendar months after a birthday, the weekday it falls on, how far away it is, and the age reached on that day.

Turns your own weekly spend per adult into a monthly and yearly grocery budget for the household, counting teenagers and children separately.

Works out what a charge costs from the kWh added, your own electricity price and the charging loss, then compares the cost per mile against gasoline at a price and an MPG you enter.

Turns a file size and a connection speed into a transfer time, keeping megabits and megabytes straight and taking protocol overhead off the line rate.

Runs an asset through straight line, declining balance, double declining or sum of the years digits, and prints the full year by year schedule.

Works out the interest paid between any two payment numbers on an amortising loan, or across one year of it, with the principal and balances alongside.

Turns a volume in cubic feet into the square feet it covers at a depth you set, and back again, with square yards, square metres and cubic yards alongside.

Adds up countertop square footage run by run, counts the finished edge in linear feet, and prices both from the figures your fabricator quoted.

Prices a concrete pour from its dimensions: the yards actually ordered, the short-load charge on a small load, delivery, pump hire and placing labour.

Total to HDL and LDL to HDL cholesterol ratios, plus non-HDL cholesterol, from the numbers already on your lipid panel, with the usual reference bands.

Scores a pairing of two Chinese zodiac animals using the traditional harmonies, clashes and harms between the twelve branches, plus their fixed elements.

Works out how many battens fit a wall, the real gap between them once they divide evenly, the linear feet of lumber and the boards to buy.

Turns a battery capacity in mAh and a device load in mA into a runtime, with a derating factor, and works out the life of a duty cycled device that sleeps between wakes.

Works out the loan to value ratio on a car loan, the balance measured against what the vehicle is worth, and shows the negative equity and gap that sit above it.

Divides AST by ALT to give the De Ritis ratio, with the inverse, the band the figure falls in and each enzyme against your own laboratory's upper limit.

Finds the length of a circular arc from the radius and central angle, with the chord, the sector area and the segment area alongside it.

Tank volume, surface area, filter turnover and the ammonia and nitrate a stocking plan produces, worked out from the fish you actually intend to keep.

Converts a nominal interest rate and a compounding frequency into the annual percentage yield, runs the conversion backwards, and compares two accounts side by side.

Projects yearly mileage from two dated odometer readings, and shows whether a lease allowance will be blown and what the excess miles would cost.

Reduces the digits of a birth date to a single figure and shows the repeating sequence it makes, or breaks down a number you keep noticing.

Adds a column of figures and prints a tape with the running total on every line, plus the added and subtracted subtotals and an optional percentage.

Wet bulb temperature from air temperature and relative humidity using the Stull approximation, with the reverse reading for a sling psychrometer.

Works out watt hours from a power draw and a running time, from a battery's mAh or Ah rating and its voltage, or backwards into a runtime.

Roasting and thawing times for a turkey, taken from the published USDA chart, plus the hour to put the bird in the oven if you know when you want to carve.

Prices a tiling job from your own rates: tile with waste, setting materials, backer board, labour and tear-out, with a cost per square foot installed.

Work out the profit on a share trade from the shares, both prices and the commission on each side, with the break-even price and the return per year.

Turns a script or a word count into a delivery time at a named speaking rate, and works backwards to the number of words that fit a time slot.

Board length from rider weight, ability and the kind of riding, plus the waist width your boot size needs, with the sizing rule stated in the answer.

Works out the reactions, the shear force and the bending moment along a simply supported beam or a cantilever carrying a point load, a uniform load, or both.

Estimates the calories a ruck costs using the Pandolf load carriage equation, which takes the weight of the pack, the grade and the terrain, not just the pace.

Works RSA through on small primes: the key pair, the encryption and decryption of a number, and the extended Euclid step that produces the private exponent.

Portions a raw diet by percentage of body weight and splits the daily weight into muscle meat, raw edible bone, liver and other organ.

Works out how much shock a pool needs to reach a free chlorine level, or to reach breakpoint from a combined chlorine reading, at the strength you pick.

How much water a run of pipe holds, looked up from the nominal size and wall schedule, plus the velocity and fill time at a given flow rate.

Turns a strong acid or base concentration into pH and pOH, works back from a measured pH, and gives the pH of a diluted solution.

Compares two values against their mean, which makes the answer the same whichever way round you enter them, and also gives percent error against a known value.

Add up a drawer of cash by entering how many of each note and coin you have, and see how many bank rolls the coins make and what is left loose.

Works out the molar mass of any chemical formula from a built-in periodic table, handling nested brackets, hydrates and the percentage each element contributes.

Estimates MCAT section scores and the 472 to 528 total from practice raw scores, and works out exactly what the last section needs for a target total.

Sizes the series resistor for an LED from supply voltage, forward voltage and forward current, in E12 and E24 values, for series and parallel strings.

A fixed table of twelve standard Laplace transforms with your own constants in them, plus polynomials in t by linearity. Symbolic algebra is refused.

Prices a laminate floor installed rather than just the planks: cartons, underlayment, labour, old floor removal and trim, with a DIY comparison.