How to use the Cutting Length of Stirrups Calculator
- 1. Enter the sectionWidth, depth or diameter, clear cover and stirrup bar size.
- 2. Set hooks and bendsHook length (10d or 75 mm), 90° and 135° bend deductions.
- 3. Get the lengthCutting length of one stirrup, number of stirrups, total length and weight.
Stirrup cutting length formula
For a closed rectangular stirrup with two 135° hooks:
Cutting length = 2(a + b) + 2 × hook − 3 × 2d − 2 × 3d
Here a and b are the stirrup sides. Measured along the centre line of the bar, a = B − 2 × cover − d and b = D − 2 × cover − d. There are three 90° corners (2d each) and two 135° hook bends (3d each). The hook is commonly 10d or 75 mm, whichever is more.
A circular tie is π × Dc + 2 hooks, and a helix is the number of turns × √((πDc)² + pitch²).
Worked example and site tips
Beam 230 × 450 mm, clear cover 25 mm, 8 mm stirrups: a = 230 − 50 − 8 = 172 mm, b = 450 − 50 − 8 = 392 mm. Cutting length = 2(172 + 392) + 2 × 80 − 48 − 48 = 1192 mm. For a 4 m beam at 150 mm spacing you need 4000/150 + 1 = 27 stirrups = 32.2 m = 12.7 kg.
- Some books measure a and b to the outer face (B − 2c). The tool lets you choose, so match your textbook.
- Near supports stirrups are often closer. Work out each spacing zone separately.
- IS 13920 (seismic detailing) asks for 135° hooks of at least 6d and 65 mm; many sites still use 10d.
Frequently asked questions
What is the cutting length of a stirrup?
It is the straight length of bar cut before bending, so that after bending the stirrup fits the beam or column with the required cover.
Why are there three 90° bends and two 135° bends?
A closed rectangular stirrup has four corners. One corner is where the two 135° hooks are, so three corners are plain 90° bends and the hooks add two 135° bends.
How many stirrups do I need?
Number = member length / spacing + 1, rounded down before adding one. Work out each spacing zone separately.
Is this calculator free?
Yes. You fill a short form once to see your result, and other Uncodemy tools then open without the form. Everything is calculated in your browser and nothing you type is uploaded.