Math & Numbers
Convert between different volume units (liters, gallons, cups, cubic meters, etc.)
volume-converterMath & Numbers
Convert between different weight units (kilograms, pounds, ounces, grams, etc.)
weight-unit-converterMath & 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
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 sample variance, population variance, and optional standard deviation for a numeric dataset
variance-calculatorMath & Numbers
Perform core vector operations such as addition, subtraction, scaling, magnitude, normalization, angle, and distance
vector-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
Complete truth table (≤ 6 variables, 64 rows) with alphabetical variable order, per-row function values, and canonical Σm/ΠM forms.
truth-table-generatorMath & Numbers
Convert thermal resistance between K/W (kelvin per watt, SI base), °C/W (1 = 1 K/W, since Δ1 K = Δ1 °C exactly), and °F·h/BTU International Table (1 = 1.8956342 K/W). Converts via K/W to the target unit and lists the equivalent value in all three units for reference. Reference values: CPU heatsink ≈ 0.1–0.3, LED thermal path ≈ 5–20, natural convection ≈ 1 K/W.
thermal-resistance-converterMath & Numbers
Convert thermal conductivity between W/(m·K) (watt per metre-kelvin, SI base, = W/(m·°C)), kcal/(m·h·°C) (1 = 1.1627778 W/(m·K)), and BTU/(hr·ft·°F) (1 = 1.7307347 W/(m·K)). Converts via W/(m·K) to the target unit and also lists the equivalent value in all three units for reference. Reference values: copper ≈ 401, aluminum ≈ 237, steel ≈ 50, water ≈ 0.6, air ≈ 0.026, insulation foam ≈ 0.03 W/(m·K).
thermal-conductivity-converterMath & 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-converter