How do you calculate a leakage test pass rate?

Divide the number of sections that passed by the total sections tested. With 237 of 250 sections passing, the pass rate is 94.8%, which is 0.2 points short of a 95% target.

What is a good duct leakage pass rate?

For a tightly specified system you want 95% or better, with the failed sections re-sealed to 100% before final signoff. A pass rate in the low 90s signals systemic sealing problems, not just a few bad joints.

What does the gap to target mean?

It is the percentage-point shortfall between your pass rate and your acceptance target. The 0.2-point gap in the example means roughly one more section needs to pass to hit a 95% target — re-seal and retest the closest failures first.

Why use pass rate instead of total leakage CFM?

Pass rate is fast to track during commissioning and maps directly to a yes/no acceptance decision. Total leakage CFM tells you the energy impact, so use both — pass rate for accountability and CFM for severity.

How many sections failed in the example?

Out of 250 tested, 237 passed, so 13 sections failed. Those 13 are your re-seal worklist; retesting even one or two of them moves the pass rate above the 95% target.

Does passing 94.8% mean the system is acceptable?

Not against a 95% target — it falls 0.2 points short, so the system is not yet acceptable. Re-seal the failed sections and retest until you meet or exceed the target before commissioning signoff.

HVAC Ductwork, Air Handling & Mechanical Products calculator

Duct Leakage Test Pass Rate Calculator

Leakage Test Rate measures the share of duct sections or zones that passed a pressurization leakage test, and how far that result sits from your acceptance target. Commissioning agents, QA managers, and TAB technicians use it to certify a duct system against a SMACNA leakage class or a project spec before signoff. A duct system that leaks wastes fan energy, starves terminal units, and fails commissioning — so tracking pass rate against a target tells you whether the install is acceptable or whether specific sections need re-sealing and retest. The gap-to-target output is the actionable number: it tells you exactly how short of acceptance you are.

What this calculator does

Calculate the duct leakage test pass rate for fabricated or installed ductwork sections. Compare the number of sections that pass pressurization testing to the total tested, and check the gap against your acceptance target.
Use this when tracking leakage test results on fabricated duct sections, installed ductwork systems, or air handling unit casings. Pressurization testing per SMACNA standards confirms that joints and seams meet the specified leak class. Tracking the pass rate over time helps identify trends in seam quality, sealant application, or joint assembly issues before they accumulate on the job site.
It computes the leakage-test pass rate as sections passed divided by sections tested, and the gap in percentage points between that rate and your acceptance target.

Formula used

Leakage test pass rate = sections passed ÷ total sections tested
Gap to target = target pass rate - calculated pass rate

Inputs explained

Sections or zones that passed leakage test:
Total sections or zones tested:
Pass rate acceptance target:

How to use the result

Use it during commissioning or QA signoff to certify duct leakage performance and to decide whether re-sealing and retesting are required.
It is a count-based pass/fail metric and says nothing about how badly the failed sections leak or their total CFM loss — a near-miss section and a wide-open seam count the same, so pair it with measured leakage rates for severity.

Current U.S. benchmarks

Industrial electricity averages 8.66 cents per kWh across the U.S. (EIA, Apr 2026), up 5.5% from a year earlier. Energy-intensive steps carry this directly into unit cost.
U.S. housing starts run at 1,177k per year (Census, May 2026), down 8.7% from a year earlier, the demand driver for building products.

Common questions

How do you calculate a leakage test pass rate? Divide the number of sections that passed by the total sections tested. With 237 of 250 sections passing, the pass rate is 94.8%, which is 0.2 points short of a 95% target.
What is a good duct leakage pass rate? For a tightly specified system you want 95% or better, with the failed sections re-sealed to 100% before final signoff. A pass rate in the low 90s signals systemic sealing problems, not just a few bad joints.
What does the gap to target mean? It is the percentage-point shortfall between your pass rate and your acceptance target. The 0.2-point gap in the example means roughly one more section needs to pass to hit a 95% target — re-seal and retest the closest failures first.
Why use pass rate instead of total leakage CFM? Pass rate is fast to track during commissioning and maps directly to a yes/no acceptance decision. Total leakage CFM tells you the energy impact, so use both — pass rate for accountability and CFM for severity.
How many sections failed in the example? Out of 250 tested, 237 passed, so 13 sections failed. Those 13 are your re-seal worklist; retesting even one or two of them moves the pass rate above the 95% target.

Last reviewed 2026-05-12.