Duct Calculator Elite vs WeldCalcs

Duct Calculator Elite™ replaces your ductulator wheel with fast, precise duct sizing built on the friction-loss equations of the ASHRAE Handbook — Fundamentals. Trusted by HVAC professionals, mechanical engineers, and contractors since 2013. One price — no subscriptions, no ads, no accounts. THREE CALCULATORS, ONE TAP APART • DUCT SIZE BY AIRFLOW — Set airflow and either velocity or friction, and solve for round and rectangular duct dimensions. Specify the rectangular aspect ratio to match your available space. The nearest standard round and rectangular sizes are shown with the friction they actually run at. • DUCT SIZE BY DIMENSION — Enter a round diameter or rectangular height and width, then lock airflow, velocity, or friction and solve for the remaining variables. • PRESSURE DROP — Convert between duct length, pressure drop, and friction. Find the exact pressure drop of a given installation, or the maximum duct length that maintains your design pressure drop. DESIGN TOOLS • FRICTION RATE — Enter your available static pressure and duct run, add fittings from a built-in list of typical equivalent lengths (elbows, tees, wyes, supply boots), and get your total effective length and target friction rate — the Manual D style residential design workflow. Then send the result straight into Duct Size by Airflow with one tap. • AIRFLOW FROM HEAT LOAD — Enter a sensible heat load and temperature difference to get the required airflow, corrected for air density. ENGINEERING-GRADE MATH Solves the Colebrook friction-factor equation directly for each duct material's surface roughness — the same method behind the ASHRAE friction chart — rather than interpolating from lookup tables. Roughness values come from Table 1 of the 2025 ASHRAE Handbook — Fundamentals, and the app shows you the one it used. Rectangular results use the Huebscher equivalent-diameter equation; air density is corrected for your temperature and elevation, and air viscosity for your temperature, so results hold up at altitude and outside room temperature. Below the turbulent range where the published methods agree, results are flagged as approximate. PRECISE ENTRY, BUILT FOR THE FIELD Type exact values directly in place — no cumbersome sliders, no pop-up entry screens. Confirm with a tap and every dependent value recalculates instantly. A clean layout keeps every result in view as you work, and everything runs fully offline. CONFIGURED FOR REAL JOB CONDITIONS • Duct dimensions: inches, centimeters, or millimeters • Airflow: CFM, cubic feet per second, cubic meters per second, cubic meters per hour, or liters per second • Velocity: feet per second, feet per minute, or meters per second • Pressure loss: inches of water per 100 ft or pascals per meter • Duct materials: galvanized steel, spiral steel, galvanized spiral (corrugated), aluminum, uncoated carbon steel, PVC plastic pipe, concrete, phenolic duct (pre-insulated), flexible duct (metallic), flexible duct (helix core, insulated), fibrous glass liner (spray coated), and fibrous glass liner (faced, smooth) • Air temperature (°F, °C, K) and elevation (feet or meters) corrections The next time you head to a meeting or out to the job site, leave the ductulator at home — everything you need is on your iPhone or iPad. Questions or ideas for the next version? Email techsupport@cyberprodigy.com — we read every message.

Useful for the preliminary sizing of fillet welds, WeldCalcs is an engineering calculator app that computes the section properties for typical welding patterns used in steel construction. After selecting a Weld Group, the user enters the dimensions for the depth and width, along with any combination of applied forces and moments. The section properties for the Weld Group, including the area, section moduli and polar moment of inertia, are instantly calculated. The app also determines the maximum resisting resultant force and the initial fillet weld size. The calculations performed by the WeldCalcs app are based on the Elastic Method. This approach treats the weld as a line or a group of lines. This allows the weld group section properties to be determined without knowing the size of the weld. The section properties and the applied loads are used in structural engineering formulas to determine the maximum resisting resultant force along the weld. This resultant force is expressed in terms of force per unit length. Since the weld is evaluated based on a force per unit length, in lieu of stresses, combining the effects from different load types (shear, axial, moment, torsion) is easily accomplished. The applied moments and torsions are resolved into vertical, horizontal and axial components and then vectorially combined with the directly applied shears and axial forces. All of the applied loads are assumed to act through the center of gravity of the weld. Therefore, each segment of the weld resists an equal share of the direct shear and axial forces and a proportional share of the bending moments and torsions relative to the weld segment's distance to the neutral axis of the weld group. The fillet weld size is determined by dividing the maximum resisting resultant force by the available strength of the weld. For practicality, both weld dimensions 'd' and 'b' are limited to a minimum value of 0.25 inches and a maximum value of 100 inches. Dimensions 'tw' and 'tf' are limited to a minimum value of 0.125 inches and a maximum value of 10 inches. The applied forces are limited to a range of -99,999 to +99,999 kips. The applied moments are limited to a range of -99,999 to +99,999 kip-inches. The equations for the section properties and resultant forces used by the app are available for reference and manual verification by the user. The general equations for the resisting forces in each quadrant are based on the applied forces and moments all acting in the positive direction.