Calculate the curved portion and total extension of a reinforcing-bar hook using your selected angle, diameter, radius and straight tail. The model keeps project assumptions visible instead of hiding them.
Enter the hook dimensions.
The tool separates the hook into two understandable components: the centerline arc created by the bend and the straight tail after the bend. Arc length is calculated as θ × R, with the angle converted to radians. The displayed hook-path length is arc plus tail.
There is no single tail length that applies to every structural situation. Hook requirements can depend on bar diameter, concrete strength, confinement, seismic detailing, member geometry and the governing code. A user-entered tail makes the assumption explicit.
A 16 mm bar with an 80 mm centerline radius and a 90° bend has an arc of about 125.66 mm. With a 150 mm straight tail, the modeled hook path is about 275.66 mm.
The bend angle changes the curved path directly. A 180° hook contains twice the 90° arc length for the same centerline radius, while a 135° hook lies between them. This is why using a generic “hook allowance” can produce avoidable length errors.
No. It calculates the geometry you specify. Code-required extension and minimum bend diameter must be checked separately.
This tool requests centerline radius so the arc calculation has an unambiguous reference.
Yes for pure geometry, although a structural hook normally has a specified extension or detailing requirement.