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.

Math & Numbers

Variance Calculator

Calculate sample variance, population variance, and optional standard deviation for a numeric dataset

Math & Numbers

Vector Calculator

Perform core vector operations such as addition, subtraction, scaling, magnitude, normalization, angle, and distance

Math & Numbers

Transportation Problem Solver (Min-Cost Flow)

Balanced transportation problems as min-cost flow: successive shortest paths, MODI duals, reduced-cost optimality certificate, and full shipping plan.

Finance

Treasury Yield-Curve Nelson-Siegel / Svensson Bootstrap

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.

Math & Numbers

Truth Table Generator

Complete truth table (≤ 6 variables, 64 rows) with alphabetical variable order, per-row function values, and canonical Σm/ΠM forms.

Math & Numbers

Thermal Resistance Converter (K/W / °C/W / °F·h/BTU)

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.

Math & Numbers

Thermal Conductivity Converter (W/(m·K) / kcal / BTU)

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).

Math & Numbers

Torque Unit Converter (N·m / lbf·ft / kgf·m / lbf·in)

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.