ChekDuct vs Static Pressure & Duct Check

Struggling to read your ductulator? Chekduct is a straightforward, reliable duct calculator built specifically for HVAC installers, service techs, and sheet metal fabricators who need info quick. Whether you’re troubleshooting an airflow issue on a service call or sizing duct for a new install, Chekduct handles the math so you don't have to

Free, offline, no account. Read total external static pressure, check what an existing duct can actually move, size a new run, or design the whole system and export the schedule as a PDF. Every result shows what it assumed. Static Pressure & Duct Check is built for the retrofit and service call, not the drafting table. Most duct problems walk in as a static reading or a homeowner's hot room, and this app starts there. DIAGNOSE • Static Pressure Check — enter supply and return static plus the equipment's rated max and get total external static pressure (TESP), a clear over / within / under verdict, headroom, and which side carries more of the total. Probe-placement guidance for furnace-plus-coil and air-handler setups. • Duct Check — enter an as-built duct (round, rectangular, six materials, flex with compression) and read back the honest CFM range it can carry. Add a target airflow for an undersized / adequate / oversized verdict with friction rate and velocity. • No airflow number handy? Estimate CFM from tonnage right where you need it. SIZE A RUN • Quick Size — enter CFM and get the stocked duct size, round, rectangular, or flat-oval, with velocity and the governing constraint. Or scan the all-sizes table to see every candidate judged on friction and velocity. DESIGN A WHOLE SYSTEM (MANUAL D METHOD) • Walk Setup → Friction Rate → Runs → Summary and leave with a run-by-run duct schedule. • Static-pressure budget with honest defaults — an overridden default never masquerades as an assumption. • Size every trunk and branch: supply and return, flex with compression, altitude-corrected airflow. • In a hurry? Start from an assumed friction rate and refine when you have real numbers. SAVE, SHARE, DELIVER • Saved projects with automatic save — walk away mid-job, pick it up tomorrow. • Share any result by text, or export the Summary as a clean PDF or CSV for the homeowner, the inspector, or the office. • Light and dark mode. BUILT HONEST • Every result shows what it assumes, so you can sharpen it. • Plausibility checks flag implausible inputs as "check your inputs," never a confident wrong answer. • Stocked round sizes and role-based velocity limits reflect real-world practice. • Anything you share or export carries the same caveats you see on screen. PRIVATE BY DESIGN • Works fully offline. No sign-in, no cloud, no ads, no tracking. Nothing you enter leaves your phone unless you choose to send feedback from Settings — and you see exactly what goes out before you tap send. NEED THE PERMIT PACKAGE? Inspectors ask for a Manual J load calculation alongside the duct design. Our sister app, HVAC Load Calculator Manual J, produces that report; this app points you to it when a job calls for one. Static Pressure & Duct Check is a field estimator based on ACCA Manual D methods. It is a professional aid, not a substitute for a stamped Manual D design or measured commissioning.