Online Calculators & Tools

Work out the required minimum distribution from a traditional IRA or workplace plan using the IRS Uniform Lifetime Table, and project the distributions forward.

Left, right, midpoint and trapezoidal sums for one integrand at once, with the strips drawn, the exact value from the antiderivative and each rule's error.

Decide whether a number is rational or irrational, with the exact fraction when it is one and the named theorem when it is not.

Work out the range, maximum height, flight time and trajectory of a projectile, with or without a launch height, and find the angle or speed that hits a target.

PCR primer Tm by nearest-neighbour thermodynamics, with the 2 + 4 Wallace rule and the GC formula printed beside it so the gap between them is visible.

Find the sample size a study needs, or the power it already has, for comparing two means or two proportions, using the noncentral t distribution rather than a shortcut.

Price a plumbing job from the fixture count, separate rough-in and finish rates, pipe runs, permits and markup, or work out what a single service call should come to.

Solves Darcy-Weisbach backwards: the water flow a pipe passes for the pressure you have, or the bore a target flow needs inside a loss budget.

Find the outliers in a list by the IQR fence rule, the z-score, the modified z-score on the MAD and Grubbs' test, and see where the four disagree.

Old School RuneScape combat level from your seven stats, with the working shown and the exact levels needed to reach the next combat level.

Odds ratio from a 2 x 2 table with the log-scale confidence interval, the Haldane correction for an empty cell, and the relative risk printed beside it.

Occupant load from floor area using IBC 2021 Table 1004.5 factors, with the exits, egress width and corridor width that load requires.

Simulates thousands of retirement drawdowns with volatile returns and reports the whole percentile band, not just a success rate. Same inputs, same answer.

Finds the cost of one more unit, from two production levels or from a cost curve, and shows where marginal cost crosses average cost.

Differentiates log_b(u(x)) by the chain rule, and does logarithmic differentiation of a product, a quotient or a variable exponent.

Orders a mixed list of integers, decimals, fractions, mixed numbers, percentages, square roots and multiples of pi, showing each one converted.

Finds k in y = k/x from a table of pairs, fills the gaps, and says whether the numbers really are an inverse variation at all.

Arcsec, arccsc and arccot of a value in degrees, radians, gradians and DMS, with the principal range and both arccot conventions.

Works out the gross bonus or relocation payment needed to leave an exact net, by the flat supplemental rate or by walking the tax brackets.

Read your four GED subject scores against the 145, 165 and 175 marks, see which subjects pass, and work out exactly what is still needed in each one.

Builds the full gear inch chart for a bike: every chainring against every cog, with the range, the duplicate gears and the size of each shift.

Works out g-force four ways: stopping or launching over a distance, a banked turn, a spin in revolutions per minute, and an impact after a fall.

Estimate free and bioavailable testosterone from total testosterone, SHBG and albumin using the Vermeulen equation, with both fractions and the constants shown.

Price a foundation repair from the pier count your wall needs and the rates you were quoted, with crack, bracing and drainage work costed separately.

Expected value, variance and standard deviation from a list of outcomes and probabilities, with the working shown outcome by outcome and the probabilities checked against one.

Decides whether two algebraic expressions are the same by expanding both to an exact canonical form, with the difference and a counterexample.

Dilates a point or a figure about any centre, giving the image coordinates, the coordinate rule and the length, perimeter and area factors.

Simplify (f(x+h) - f(x))/h for a polynomial, exactly, and see the limit as h approaches zero. Also evaluates the quotient at a chosen x and step size.

Exact odds for any dice roll: the chance of a total, of keeping the highest or lowest dice, and of rolling with advantage or disadvantage.

Turns a calendar date into its day number within the year, and a day number back into a date, with the days remaining, the quarter and the ISO week.

Predicts puppy coat colours from six dog coat loci at once, handling the way recessive red, dominant black and merle hide everything underneath them.

Works out a name number on the Chaldean chart, where letters run 1 to 8 and no letter is ever a 9, and reads the two digit compound number as well as the root.

Estimates the extra daily energy breastfeeding costs, from the baby's age and how much of the feeding is breast milk, or from a milk volume you have measured.

Works out the ankle-brachial index for each leg from four ankle pressures and two arm pressures, with the published bands and the calcified-vessel caveat.

Builds a trip budget from daily spending, nights, flights and a contingency, and reports the cost per person per day as the headline figure.

Works out a USSSA playing age from a date of birth and the program's determination date, then names the age group the player belongs in.

Turns two quantities into a unit rate and its reciprocal, and ranks up to four pack sizes at once to show which one is cheapest per unit.

Works out GD&T true position as twice the radial deviation from the basic location, with the bonus tolerance a circle M or circle L modifier earns.

Scales a standing tree into board feet from its diameter, merchantable height and form class, then prices it on Doyle, Scribner or International.

Adds static lift, pipe friction, pressure head and velocity head into the total dynamic head a pump has to deliver at your design flow.

Turns a daily step count into a calorie deficit and a range of likely weight change, showing both the 3,500 rule figure and the smaller one that allows for adaptation.

Sizes a solar battery bank from daily energy use, days of autonomy and depth of discharge, and compares lead acid against lithium on usable capacity.

Prices a septic system line by line: tank, excavation, drainfield, perc test, design, permits and restoration, with every rate an input you can overtype.

Turns a Galloway run-walk ratio and its two paces into one overall pace and a finish time, and solves backwards for the running pace a target needs.

Works out how much renters insurance cover you need: contents from a room-by-room inventory, replacement cost against actual cash value, liability and the deductible.

Clears a square root out of a denominator, either a single surd or a sum handled with its conjugate, with every step shown and the surviving root simplified.

Fills in the missing cells of a ratio table, shows the scale factor behind each column, and checks that the columns you already had agree with each other.

Works out the urine protein-to-creatinine ratio in mg/mg, mg/g and mg/mmol, grades it against the KDIGO bands and estimates the 24-hour protein.