Stirrup Length and Quantity Calculator

How is stirrup length calculated?

The cutting length of a closed rectangular stirrup is the sum of its four sides plus two hooks. The outer dimensions of the stirrup are the section dimensions less the cover on both sides:

L = 2 × (b − 2c) + 2 × (h − 2c) + 2 × hook − bend deduction

A bar stretches slightly when it is bent, so fabricators deduct a small amount from the cutting length. That deduction depends on the rule in use, which is why it is your input here.

How many stirrups?

At uniform spacing the count is the member length divided by the spacing, plus one. Where stirrups are closer at the ends of columns and beams, each end zone and the middle zone are counted separately. The calculator places the first stirrup at a set distance from the end, steps through the end zone at the close spacing and divides the rest by the middle spacing.

Example

A 30 × 50 cm section with 3 cm cover and 10 cm hooks: outer dimensions 24 × 44 cm, cutting length 2 × 24 + 2 × 44 + 20 = 156 cm.

A 3 m member with 10 cm spacing over 60 cm at each end, 20 cm in the middle and the first stirrup 5 cm from the end: 7 at each end, 8 in the middle, 22 in total. For 8 mm bars that is 34.32 m and 13.5 kg.

Limits

This is a quantity tool, not a design tool. End zone lengths, spacings, minimum stirrup size and hook shape follow the seismic code and the structural design. Calculate cross ties and multi leg links separately.