Update log
New tools, coefficient improvements and methodology changes — so you know when a number might differ from last time.
- New tool
Equivalent length, fan static, Q = V × A and unit converter
Four new calculators. Equivalent length is derived from the same fitting coefficients as the Fitting Loss calculator (L = C × D / f).
- Improvement
Printable reports and shareable links on every calculator
Each calculator now keeps its inputs in the page address and prints a clean report with date and link.
- Methodology
Calculation basis published for the Fitting Loss calculator
Coefficient source (ASHRAE Handbook—Fundamentals 2021, Ch. 21), equations, air assumptions, units and rounding are now shown on the page. About page added.
- Guide
Duct material types guide
Roughness values, design friction-rate ranges and best uses for metal, flex and fiberglass duct.
- Improvement
Shared Project Library
Saved runs are visible to all visitors, with interpretation, next-size comparison and what changed between runs. Industry example projects added.
- Methodology
Next-size comparison aligned with sizing results
The 'calculated size' row now uses the exact displayed diameter rather than the nearest standard size.
- Guide
Duct design knowledge base
Eight guides on friction loss, friction rate, fitting coefficients, equal-friction design, critical path, static pressure and worked examples.
- Improvement
Result interpretation on every calculator
Plain-English meaning, warnings for unusual velocity or losses, what to check next, and neighboring standard sizes.
- Guide
Sizing guides and velocity limits
CFM-to-duct-size, round vs rectangular, flex vs rigid, velocity limits and standard duct dimensions.
- New tool
Project plan, code compliance and contractors
Regional cost-based project plans with PDF export, ASHRAE/NFPA/local code notes and a contractor directory.
- New tool
Calculator suite
Duct velocity, fitting loss, duct weight, rectangular-to-round converter and CFM size chart.
- New tool
Commercial duct sizer launched
Round and rectangular sizing from CFM and friction rate using Darcy–Weisbach with Altshul–Tsal friction factor.