Online Calculators & Tools

Turns building measurements and a pitch into sloped roof area and squares, plus rafter length, ridge, eave and rake runs and the roof angle in degrees.

Works out how long a retirement balance lasts at a given withdrawal, or how much may be withdrawn for it to last a set number of years.

Works out the bags of salt a saltwater pool needs to reach its target salinity, and how much water to replace when the reading is too high.

Works out Pokemon type matchups from the eighteen type chart. Pick a single or dual typing for its weaknesses, or a move type for its damage multiplier.

Separates documented medical costs and lost income from a pain and suffering range built on a multiplier you choose. Not a case valuation.

Project your next period dates, the estimated ovulation day and the fertile window from your last period and your usual cycle length.

Find the percent increase or decrease between two values, apply a percent change to a number, or work back to the value a known change started from.

Convert powder in milligrams and bacteriostatic water in millilitres into a concentration, a draw volume and U-100 insulin syringe units.

Plan the soft drinks, mixers, bottled water, ice and cups for a party from your guest count, the hours and how many guests skip alcohol.

Enter any two of voltage, current, resistance and power and get the other two, with the formula used and unit prefixes from microamps up to kilovolts.

Estimates maximum heart rate from age using four named published equations, and shows how far apart they are instead of hiding behind one.

Finds the internal rate of return on an uneven series of cash flows, solved numerically, with the net present value at any discount rate alongside it.

Finds the inverse of a linear, rational, power, exponential or logarithmic function from its coefficients, with the swap and solve steps written out.

Solves linear, quadratic, absolute value and compound inequalities from their coefficients, in inequality and interval notation with the steps shown.

Build a line-by-line budget for a new house: living space, garage, site work, design fees, contingency and land, each shown with its own figure.

Work out your five training zones in beats per minute by the Karvonen heart rate reserve method, from your age and resting pulse.

Work out the doubling time and percentage change between two quantitative beta hCG blood results and the hours between the draws.

Counts the terms left to a degree from credits remaining and credits per term, and works the other way to find the load needed to finish on time.

FIRE stands for Financial Independence, Retire Early. Works out how many years of saving separate you from the point where investments cover your spending.

Works out the score you need on the final exam to reach a target course grade, from your current grade and the weight the syllabus gives the final.

Turns watts and hours into kilowatt hours and money. Cost an appliance per hour, day and year, or price a metered reading with standing charges.

Finds the eigenvalues and real eigenvectors of a 2 x 2 or 3 x 3 matrix by solving the characteristic polynomial exactly, complex pairs included.

Gives the domain and range of seven named function families in interval notation, with the asymptote, vertex or endpoint that produces the answer.

Dividend income from shares, price and yield, a year by year projection with reinvestment, and the payout ratio from earnings per share.

Solves first order linear, logistic and second order homogeneous differential equations exactly from numeric coefficients and initial conditions.

Counts the deck boards, screws, joists, beam, posts, footings and railing pieces a simple rectangular deck needs from its length and width.

Works out one billing cycle of card interest from the daily periodic rate, and shows how much of a single payment is swallowed by that interest.

Count the CMU blocks, mortar bags and courses for a block wall from its length and height, and the grout needed if the cores are filled.

Works out a commercial property loan payment over a long amortization, the balloon left when the shorter term matures, and the debt service coverage ratio.

Works out the calving date from a breeding date using a 283 day gestation, with a window either side, or works backwards from the calving date you want.

See the larger loan a cash-out refinance leaves behind: new balance, loan-to-value, the new payment and what the released cash costs over the term.

Prices carpet from the roll rather than the floor area: full width runs, which way to lay them, seam count, linear feet to order, padding and fitting.

Builds the full amortization schedule for a car loan, listing every payment with its interest, principal and remaining balance, or one line per year.

Cash down a car deal needs once sales tax, dealer fees and a trade-in that may still carry a loan are counted, or worked back from a target payment.

Works out the daily calorie deficit a weight loss deadline demands, the intake it leaves you, and whether that pace is a sensible one.

Works out body surface area in square metres from height and weight using the Mosteller, Du Bois, Haycock and Gehan and George formulas side by side.

Sorts bust, waist and hip measurements into one of six named body shape bands using the FFIT for Apparel rule set, with every threshold printed.

Bullet drop, wind drift, retained velocity and energy from muzzle velocity, G1 ballistic coefficient, zero range and sight height, with a drop table.

Resize an image or video while the proportions hold, read the ratio off a pixel size, or fit one ratio inside a frame and see the bars it leaves.

Turn an annuity balance into monthly income: for a fixed term, for a life you choose to plan to, or at a level that never spends the principal.

Estimate monthly and annual profit from a short-term rental, with platform and management fees, cleaning per stay, fixed costs and break-even occupancy.

Work out alcohol by volume from your original and final gravity readings, on both the simple homebrew formula and the more accurate alternate one.

Scores two sun signs against the traditional aspect and element tables and returns a percentage, the aspect name and both elements. Entertainment, not advice.

Volume of a sphere, a cone or a rectangular pyramid from its radius or base and height, converted to cubic feet, cubic metres, litres and gallons.

Find the current in amps from a voltage and either the watts or the ohms, for DC, single-phase AC with a power factor, or three-phase AC.

Turn a Unix epoch value into a readable date, or a date into a timestamp. Handles seconds and milliseconds, UTC and fifteen local time zones.

Solves a triangle from three known parts with the sine and cosine rules, returning the missing sides and angles, area, perimeter, circumradius and inradius.

Works back from the monthly payment you can afford to the travel trailer price it buys, after sales tax, dealer fees, cash down and a trade-in.