Online Calculators & Tools

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.

How much insulation an area needs for its climate zone: the R-value target, the depth of loose fill to reach it, and the batt count for a framed wall.

Project what a house will be worth at an appreciation rate you choose, or find the yearly rate a home you already own has grown at, with or without inflation.

Curves a whole class of raw scores three ways: the square root curve, the highest score curve, and a linear rescale to a target mean and spread.

Turns a dextrose infusion that has already been prescribed into mg/kg/min, or an ordered glucose infusion rate into a pump rate in mL per hour.

Adds the three Glasgow Coma Scale components into a total and writes the E, V and M notation, with a not-testable option on every component.

Finds the geometric mean of a list of positive numbers, plain or weighted, and shows it beside the arithmetic and harmonic means for comparison.

Works out the dimensional weight of a parcel from its measurements and tells you which weight the carrier actually bills, using the divisors carriers publish.

Works out the hit point maximum for a Dungeons & Dragons fifth edition character from class, level and Constitution, on the average or a rolled total.

Customer lifetime value under three named models: subscription churn, a fixed horizon, and the retail order formula, each with the LTV to CAC ratio and payback.

Counts a cribbage hand or crib from the four cards and the starter, scoring fifteens, pairs, runs, the flush and his nobs under the right rule.

Find the carburetor CFM an engine needs from its displacement, peak rpm and volumetric efficiency, or the rpm a carburetor you already have can feed.

Costs a lease and a car loan over the same number of months, counting the equity left in a bought car against the payments and fees on a lease.

Counts the bricks and bags of mortar for a wall from its size and the brick's own face, with nine standard brick sizes and a custom option.

Expands (a x + b) raised to a whole power using the binomial theorem, term by term, with the Pascal row and the working behind each coefficient shown.

Adds, subtracts, multiplies and divides two binary numbers directly in binary, showing the carries, borrows or partial products, plus AND, OR, XOR, NOT and both bit shifts.

Converts basis points to percentages and back, measures the gap between two rates in basis points, and prices a fee quoted in bps on a balance.

Solves absolute value equations in one variable, splits each one into its two cases and checks every candidate, so an extraneous root is named rather than handed back as an answer.

Works the 457(b) rules a 401(k) does not share: the three-year special catch-up, and taking money out with no 10% penalty once you have left the employer.

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.