Calculator
Builds the true final price as a waterfall: stacked discounts, correct sales-tax base and cascade, tipping on the etiquette base with rounding, per-person split, and mid-market vs DCC conversion.
tip-sales-tax-currency-conversion-discount-stacking-calculatorMath & Numbers
Balanced transportation problems as min-cost flow: successive shortest paths, MODI duals, reduced-cost optimality certificate, and full shipping plan.
transportation-problemFinance
Bootstrap the discount-factor and spot curve from treasury quotes, fit Nelson-Siegel or Svensson parametrically, and chart spot plus instantaneous forward curves with basis-point residuals.
treasury-yield-curve-nelson-siegel-bootstrap-interpolatorMath & Numbers
2-set and 3-set inclusion-exclusion solver: every disjoint region, the union, and the outside count, with consistency checks.
venn-diagram-problem-solverMath & Numbers
Convert torque (moment of force) between N·m (SI base), lbf·ft (pound-foot), kgf·m (kilogram-force-metre), and lbf·in (pound-inch). Factors based on standard gravity g₀ = 9.80665 m/s² and 1 lbf = 4.4482216152605 N. Converts via N·m to the target unit and also lists the equivalent value in all four units for reference. Used for mechanical specs, automotive, and fastener tightening torque.
torque-unit-converterMath & Numbers
Compute the required outdoor / supply ventilation rate. ASHRAE 62.1 ventilation-rate procedure: people component Vpz = Rp·P, area component Vaz = Ra·A, breathing-zone outdoor air Vbz = Vpz + Vaz, zone supply airflow Voz = Vbz / Ez. Three modes: ASHRAE 62.1 (people + area), per-person rate (P × Rp), or contaminant dilution (Q = G / (C_acc − C_sup), where G can be mg/s, mg/h, or L/s of gas and concentrations mg/m³ or ppm). Results reported in L/s, m³/h, and CFM.
ventilation-rate-calculatorMath & Numbers
Calculate active, reactive, and apparent power for a balanced three-phase system: S=√3·U·I, P=√3·U·I·cosφ, Q=√3·U·I·sinφ. Also returns the power-factor angle φ and verifies the power triangle.
three-phase-power-calculatorMath & Numbers
Reflect an impedance through an ideal transformer: Z' = a²·Z, where a = N₁/N₂. Supports secondary→primary and primary→secondary directions; a can be given directly or derived from N₁/N₂. Also returns admittance Y and reflected admittance.
transformer-impedance-transferMath & Numbers
Ideal transformer ratio: a = N₁/N₂ = V₁/V₂ = I₂/I₁. Given turns, voltage, or current on either side, compute a and the corresponding voltage/current on the other side; verifies V₁·I₁ = V₂·I₂.
transformer-turns-ratioMath & Numbers
Compute torque, force, or lever arm from τ = r·F·sin(θ), with the perpendicular force component shown
torque-calculatorCalculator
Estimate how many tiles you need to cover a room, including layout-aware waste (straight, 45° diagonal, herringbone, basketweave), boxes to buy, grout volume and weight, and an optional cost total. Enter room and tile dimensions plus joint width to get a ready-to-order material list.
tile-coverage-estimatorCalculator
Enter a tire size (285/70R17), differential/final-drive ratio, and transmission gear ratios to compute the true overall tire diameter, circumference, revolutions per mile/km, an RPM × gear speed table, effective final drive after a tire change, and speedometer error. Metric or imperial units, with optional before/after tire comparison.
tire-gear-ratio-calculator