Online Calculators & Tools

Counts valence electrons, places the bonds and lone pairs, checks the octets and formal charges, and draws the structure for a single central atom.

Turns a rebuild cost into the full set of homeowners limits: Coverage A, then B, C and D as shares of it, with liability kept separate and the contents and loss-of-use figures tested.

Totals a nine or eighteen hole card: gross, net after a course handicap spread by stroke index, stableford points and the adjusted gross a round is posted with.

Scores the original 1977 Goldman index across its nine weighted criteria and reports the class, alongside what that class actually did in the cohort the index was derived on.

Free water deficit in hypernatraemia from total body water and the measured sodium, with the volume the usual 24-hour correction-rate limit allows and the rate that implies.

Cardiac output and cardiac index by the Fick principle, from oxygen consumption, haemoglobin and the arterial and mixed venous saturations.

How much epoxy a mould, river channel or flood coat takes, split into resin and hardener at any mix ratio by volume or by weight.

Multiplies out a(b + c) with every individual product written down, handles any number of letters, and factors the common term back out of an expression.

Prices a deck line by line: boards, framing, posts, footings, hardware, railing, stairs, labour, tax and fees, at the prices you enter.

Works out the half-your-age-plus-seven saying: the range it produces for one age, or whether two ages fall inside it. A folk rule with no research behind it, shown as one.

Works out the cost of equity three ways: CAPM, the dividend growth model, and a bond yield plus a premium, then shows the spread between them and what each implies for the share price.

Corrected or adjusted age for a baby born early, from the due date or the gestational age at birth, with the chronological and postmenstrual ages too.

How much compost to top-dress an area at a given depth, in bags, bulk yards and weight, plus the carbon-to-nitrogen ratio of a pile and what to add to bring it to target.

Coffee and water in grams for drip, pour over, press, AeroPress, moka, cold brew or espresso, including the water the wet grounds keep back from the cup.

Nominal age by the East Asian reckoning, where a baby is one at birth and everybody gains a year at Chinese New Year rather than on a birthday.

Splits a deposit into staggered certificates, shows what each rung is worth at maturity and gives a blended yield worked out as an internal rate of return.

Adds depreciation, fuel, insurance, servicing, tyres, tax and loan interest over a whole ownership period, then turns the total into a cost per year, per month and per mile.

Draws a box and whisker plot from your data, with the five number summary, the IQR, the Tukey fences and every outlier named.

Averages a list of durations, and averages times of day with the circular mean, so 23:00 and 01:00 come out as midnight rather than as noon.

Averages percentages the right way. Enter each percentage with the group size behind it and see the weighted answer next to the plain mean of the percentages.

One-way analysis of variance for up to six groups. Returns the sums of squares, degrees of freedom, mean squares, the F statistic and an exact p value.

Turns an oven temperature and time into air fryer settings, 25 degrees lower and a fifth less time, and gives the safe internal temperatures that actually decide doneness.

Works out the acreage of a lot from its length and width, its three sides, or its corner coordinates, and converts between acres, hectares, chains and rods.

Paste a run of annual figures and get the growth from each year to the next, the total change and the compound annual rate that connects the ends.

Converts a lens power between two vertex distances, such as a spectacle prescription to the corneal plane, meridian by meridian.

Solves ax + b = c, x/a + b = c and equations with x on both sides, writing out every step with both sides shown and the answer substituted back as a check.

Evaluate a triple integral over a rectangular box, a cylindrical wedge or a spherical shell, with the inner integrals shown and a numerical check alongside.

Works out time-lapse settings in either direction: clip length, card space and batteries from an interval, or the interval that fits an event into the clip you want.

Weighs a student loan refinance rate saving against what it ends: income-driven repayment, PSLF credit and the balance that would have been forgiven.

Works out the new average cost per share after you buy more of a holding, with the break-even price and the gain it would take to get back there.

Lambing date from the breeding date on a 147 day gestation, the service date for a wanted lambing date, and the lambing period from a ram in and ram out date.

Converts between real sizes and scale sizes for models and maps, finds the ratio behind two measurements, and re-scales a size from one ratio to another.

Block, cap, levelling pad and drainage stone for a segmental retaining wall, from wall length, exposed height and the block size you are using.

Solve an equation with x in the denominator, clearing the fractions and then throwing out the extraneous roots that a plain equation solver would keep.

Strips and yardage for binding a quilt, counting the length every diagonal join eats, with straight-grain and continuous-bias cutting.

Works out the days supply from the quantity and the dose, the date the supply runs out, and the earliest date a pharmacy will usually refill it.

Plot a polar curve on a polar grid with a table of theta, r, x and y, plus the petal count, the maximum radius, the symmetry tests and the area swept.

Finds the payment at which a loan reaches 80% and 78% of its original value, the midpoint termination date, and what extra principal moves.

Scales pizza dough by baker's percentage: flour, water, salt, oil and yeast from the number of balls, their weight and the hydration you want.

Trace width from current and temperature rise by the IPC-2221 conductor charts, with copper weight, cross-section, resistance, voltage drop and power.

Muzzle energy in foot-pounds and joules from bullet weight in grains and velocity in feet per second, with momentum, power factor and Taylor KO.

Price a temporary 2-1, 3-2-1 or 1-0 mortgage buydown: the escrow the seller funds, the payment in each bought-down year, and what it climbs back to.

Area moment of inertia for rectangles, tubes, pipes, I-beams and T-sections about both axes, with section modulus, radius of gyration and the parallel axis theorem.

Builds a mold remediation estimate line by line: area, containment, HEPA scrubbing, material removal, disposal and testing, each at a rate you supply.

Turns a framing order into pieces, linear feet and board feet, with nominal sizes converted to the actual dressed dimensions and a cut list from stock lengths.

Board feet in a log under the Doyle, Scribner and International 1/4-inch rules side by side, from small-end diameter and length, with a tally for a whole load.

Draw the K-map for 2, 3 or 4 variables from your minterms and don't cares, group it, and return the minimal sum of products and product of sums.

Converts an inequality to interval notation and back, handles and, or and unions, and works out the union, intersection or difference of two intervals.