Half Round Vents are just half of a circle.
And this is how it will be measured.
An empty hole in the gable wall is a good place to start.
Place the measuring tape inside the opening and measure right across the bottom.
This will be the width measure.
Again, inside the opening, measure up to the highest point of the arch.
This is the height of the opening.
On the order page, this is referred to as "opening size".
The actual vent will be reduced by 1/4" per side to better fit the opening.
Do not attempt to reduce these measures yourself.
They will not calculate and transfer to the new vent correctly.
And will hinder the install.
To get the "tip to tip" measure, measure the vent itself.
First across the base without any flange added.
Then up the middle of the half round vent.
This only leaves choosing the depth of the vent.
If anything was overlooked or left out, feel free to contact us via
text message 901.281.2887