Online Calculators & Tools

Finds where a line or parabola crosses each axis, from standard form, slope-intercept form, two points or a quadratic, with exact fractions.

Ramp length, run, angle and landings for a wheelchair ramp, measured against the ADA 1:12 maximum slope, or the slope you get from the space you have.

Adds up a wedding from your own quotes, per-guest and flat, with each line's share of the total, an optional contingency and a check against your budget.

Adds up a tree removal quote from your own rates: price per foot of height, an access surcharge, stump grinding, hauling, permits and tax.

Computes the z test statistic for a mean with a known sigma, for one proportion against a claimed value, and for two proportions compared.

Net internal volume of a subwoofer enclosure from its outside dimensions, the sealed alignment it lands on, and the port length for a chosen tuning.

Works out the interest a student loan builds up in school and grace, what capitalises onto the balance, and how a single payment splits.

Adds up the five RMR89 parameter ratings and the orientation adjustment, then returns the rock mass class, stand-up time and shear strength band.

Works out the Robux you keep after the 30% Roblox marketplace fee, what Roblox takes, and the price to list an item at to hit a target payout.

Turns an inside circumference or diameter into a US, UK, EU/ISO and Japanese ring size, with the sizes either side, and converts between the four systems.

Shows the rent your income supports under the 30 percent threshold and under a landlord's 3x income rule, and checks a listing you have already found.

Scales recipe ingredients to any number of servings with measurable fractions and spoon breakdowns, and converts a recipe between pan sizes.

Simplifies one polynomial over another, cancels the common factor, and lists the values the variable may not take, including the ones the cancelling hides.

Backing yardage for a quilt top: how many widths of fabric to join, which way to run the seams, and how much to buy at the next eighth of a yard.

Corrects a measured QT interval to a rate of 60 beats a minute by the Bazett, Fridericia, Framingham and Hodges formulas, with the published cut points.

Solves a : b = c : d for a missing term in any of the four slots, checks whether two ratios really are in proportion, and works out inverse proportions.

Elasticity from a before and after price and quantity, by the midpoint method or from the starting values, with the revenue either side of the change.

Poisson probabilities from a mean or from a rate and an interval: exactly k events, at most k, at least k, or anywhere in a range of counts.

Takes the bookmaker margin out of a market of two to eight outcomes and returns the fair probability and price for each, by three published methods.

Works a missing side or angle through the sine rule line by line, and prints both triangles when the ambiguous case leaves two of them standing.

Estimates a value between two known data points, solves the same line backwards for x, interpolates inside a table of points and does bilinear interpolation.

Estimates the 10-year risk of a first heart attack or stroke with the American Heart Association PREVENT equations, for adults aged 30 to 79 with no known heart disease.

Costs a hard money loan as one is actually written: origination points, interest-only payments, a minimum interest guarantee and a balloon at the end.

FIB-4 liver fibrosis index from age, AST, ALT and platelet count, with the published cut-offs and the APRI index alongside it.

Fractional excretion of sodium from a matched serum and urine pair, using the published Espinel formula, with the urea version and the cut-offs that go with each.

Damage per second from hit damage, attack rate, crit chance and multiplier, with time to kill and a sustained figure that counts the reload.

Divides one decimal by another and shows the working: the decimal point shift that makes the divisor whole, then the long division line by line.

Estimates what an accident took off a car's resale value, using the 17c formula with its damage and mileage multipliers or a before-and-after comparison.

Counts the calendar days and the working days left until a deadline, and works the other way to find the date a set number of working days out.

Prices a set of D&D 5e ability scores against the 27 point budget, applies species or background bonuses, and gives every final modifier.

Static compression ratio from bore, stroke, chamber volume, gasket, deck clearance and piston dish, plus the dynamic ratio from intake valve closing.

Builds the full truth table for a boolean expression of up to four variables and reduces it to a minimal sum of products with Quine-McCluskey.

Prices a European call or put with the Black-Scholes-Merton model, returns delta, gamma, vega, theta and rho, and solves backwards for implied volatility.

Works out which plates go on each side of the bar for a target weight, in pounds or kilograms, using the fewest plates rather than heaviest first.

Estimates arrow speed in fps from a bow's IBO rating, your draw length, draw weight and arrow grain weight, with kinetic energy and momentum.

Draws z = f(x, y) as a shaded isometric surface from a 25 by 25 grid of samples, with the exact critical point and surface type for a quadratic.

Finds the real zeros of any function you can write in terms of x, by sampling the range you give and closing in on every sign change numerically.

Gives the longest run a conductor size can serve inside a voltage drop limit, and turns a cable route into the feet of wire and the spools to order.

Counts the studs in a wall at 12, 16 or 24 inch centres, with plates, corners, partition backers and the kings, jacks and cripples around each opening.

Calories burned on a treadmill from belt speed, incline and time, using the ACSM metabolic equations rather than a flat MET value, so the gradient counts.

Adds up the ACR TI-RADS points for a thyroid nodule from its five ultrasound feature categories and reports the level with the published size thresholds.

Works out the tarot birth cards for a date using the Arrien and Greer method: month plus day plus year, reduced to 22 or less. Entertainment only.

Divides a polynomial by a linear factor using the synthetic division tableau, showing the bring-down, multiply and add row by row.

Converts a race time between short course yards, short course metres and long course metres using the published distance factor and per-turn adjustment.

Gives the tilt angle for a fixed solar array from your latitude, year-round and by season or by date, plus the row spacing that clears midwinter shade.

Payment on a fixed rate second mortgage running behind a first, with the two payments added together, the combined loan-to-value and the blended rate.

A starting figure for your weight belt from the published percentage-of-body-weight bands, adjusted for exposure suit and for fresh or salt water.

Reads 3, 4, 5 and 6 band resistor color codes into ohms with tolerance and temperature coefficient, and turns a resistance back into its bands.