Static Pressure & Duct Check

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 clo