See the duct before you cut it.
Round, rectangular, flat-oval and flex duct, sized by friction rate or velocity. Turn the airflow and watch the size and the noise change together.
// friction rate from the fan
Start from what the blower can push.
Take the fan's external static pressure, subtract the filter, the coil and the registers, and spread what is left over the longest run, supply plus return. That is the friction rate the ducts can afford.
Example from the screenshots. The same in pascals per metre with one switch.
// noise
Every size gets a colour.
Ductlane compares the air velocity in each size with residential limits, recommended and maximum, separately for rigid and flex duct, or with light-commercial limits. The size next to yours shows its colour too, so the trade-off is on screen.
Within the recommended velocity.
Above recommended, still within the maximum.
Above the maximum velocity for that duct.
// features
From one duct to the whole house.
Four shapes
Round, rectangular, flat-oval and flex. Rectangular and oval duct show the equivalent diameter, so you can compare them with round directly.
Friction rate or velocity
Size by friction rate or by velocity. Drag the airflow and the friction rate and the size follows as you go.
Stock sizes
The exact size is rounded to a size you can buy: US round from 3″ to 60″, or metric EN 1506 from 63 to 1250 mm.
Friction rate from the fan
External static pressure minus filter, coil and registers, divided by the total equivalent length of supply and return.
Trunk and branch jobs
Lay out a whole house: rooms with their airflow, branch sizes and lengths, and the trunk. One job is free; Pro keeps as many as you need.
The standard method
Darcy–Weisbach with the Colebrook friction factor at standard air, the ASHRAE duct design method. IP or metric, in English, Spanish or Portuguese.
Reference values, not a stamped design. Ductlane's results are calculations for reference. They are not an engineered or stamped duct design and not your local code. Check the final sizes with a qualified professional where it matters.
// a look inside
Six screens, one duct system.
// free and pro
Sizing is free. Pro is for whole jobs.
There is no paywall in front of a duct size.
Free
$0
- Sizing any duct: round, rectangular, flat-oval, flex
- Friction rate or velocity, equivalent diameter, stock sizes
- Friction rate from the fan
- Noise colour for every size
- 1 job: trunk and branch for a whole house
Ductlane Pro
$29.99 lifetime · $19.99 / year · $3.99 / month
- Unlimited jobs
- Pressure profile from the fan to the last register
- PDF export
- Air density for altitude and temperature
- Pay once with Lifetime, no subscription needed
Prices in US dollars; the store shows the price for your country. The yearly and monthly plans renew automatically unless cancelled at least 24 hours before the end of the current period, and the account is charged within 24 hours before that date. Cancel in Google Play › Payments & subscriptions › Subscriptions. The lifetime purchase is charged once and never renews. See the Terms of Use and Privacy Policy.
// questions
The short version.
When can I get it?
Ductlane is coming to Google Play first.
How does it calculate?
Darcy–Weisbach with the Colebrook friction factor at standard air, the ASHRAE duct design method. Pro adds air density for altitude and temperature. The results are reference values, not a stamped design or your local code.
Do I need an account?
No. There is no account and nothing to log into. Your jobs and history are stored on your phone and are not uploaded anywhere. Details in the Privacy Policy.
What do I get without Pro?
Sizing any duct, in every shape, with the noise colour, plus one job for a whole house. Pro adds unlimited jobs, the pressure profile, PDF export and air density.
Size it once. Hang it once.
Round, rectangular, flat-oval and flex duct, the friction rate from the fan and the noise for every size. No account, no ads.