BoringToolsKit

Split a bill across a group after tax, tip, and optional rounding. Returns each person's share, the tip, the effective tip rate, and the collected total.

Compute the final checkout total after stacked percentage discounts, a fixed coupon, and a tax assumption. Sequential discounts are NOT additive.

Calculate body mass index and category from weight and height in US units.

Estimate basal metabolic rate (Mifflin-St Jeor) and total daily energy expenditure from age, weight, height, sex, and an activity multiplier.

Estimate the full monthly housing payment (principal, interest, tax, insurance, PMI, HOA) and the total interest over the term. Requires a positive home price.

Estimate a monthly auto-loan payment from price, down payment, trade-in, term, and APR.

Grow a balance with compound interest and optional monthly contributions. Returns future value, total contributed, and interest earned.

Project the future value of a lump-sum investment (optionally with monthly additions), including interest earned.

Compute simple interest, total value, and a comparison to annual compounding.

Estimate BMR and total daily energy expenditure using Mifflin-St Jeor, from weight/height in US units.

Solve percentage problems: what is X% of Y, X is what % of Y, or the % change from X to Y.

Compute total area (and with-waste area) from up to two rectangular spaces, plus square yards, square metres, and acres.

Compute annual percentage yield from a nominal rate and a compounding frequency, plus the one year interest and ending balance on an example deposit.

Compute a winning percentage from wins, losses, and ties, where ties count as half a win.

Compute slope from rise and run as degrees, percent grade, and the rise to run ratio. Run must be above zero.

Estimate the doubling time of money at a fixed rate using the rule of 72, plus the exact doubling time from the compound formula. Rate must be between 0 and 30 percent.

Compute the compound annual growth rate connecting a starting and an ending value over a number of years, with total return percent and absolute change.

Compute the remainder and floored quotient of a division. Works for decimal inputs, not just integers.

Compute the number of distinct combinations, n choose r, using a multiplicative form that avoids factorial overflow.

Compute the margin of error for a survey sample at the 90, 95, or 99 percent confidence level, assuming maximum variance proportions.

Monthly VA loan payment including the funding fee, with no PMI. Returns the financed amount, payment, and total interest.

Gross rent multiplier for a rental property: price divided by annual gross rent. Lower means more rent per dollar of price.

Emergency fund target (expenses times coverage months), the remaining gap versus current savings, and months to close the gap at a fixed monthly contribution.

Compound a portfolio with a constant dividend yield and price growth, reinvesting monthly and optionally adding deposits. Returns ending value, total contributed, and dividends reinvested.

Split monthly after-tax income by the 50/30/20 rule into needs, wants, and savings or debt paydown.

Accumulate growing, heating, or cooling degree days (Fahrenheit basis) from daily high, low, a base threshold, and a day count. Includes Celsius-basis totals.

U-value of an insulation upgrade and an estimated annual heating saving from conduction, using heating degree days, area, kWh conversion, and utility cost.

Roof area from footprint and pitch, with waste allowance, roofing squares, and approximate shingle bundles (3 per square).

Daily maintenance calories (TDEE) from Mifflin-St Jeor BMR and an activity level, using metric inputs.

Estimate a protein chain molecular weight in Da and kDa from residue count and average residue mass, plus peptide bond count.

Transpose a musical key and report the number of semitone steps upward between two keys.

Compute the new duration of audio at a playback speed, plus the percent time change.

Estimated YouTube Adsense revenue from monthly views and RPM, with an annual figure and a 30 percent RPM swing range. RPM defaults to 2 when omitted.

Count 2x2 ft ceiling tiles needed for a rectangular room, with room area and a 5 percent cut-waste reminder.

Boat or RV loan payment with optional sales tax, down payment, and trade-in, including amount financed and total interest.

Compute pressure in Pascals, kilopascals, and psi from a force in newtons over an area in square metres.