“Easy Binding Wire Calculation Formula for Bar Bending Work”

 

1: Binding Wire in Construction: Size, Weight & Easy Calculation Guide

Binding wire is a small but very important material in construction. It is mainly used for tying reinforcement bars (rebars) so that they hold their position before and during concreting. Although it looks simple, engineers and contractors must know the correct size, weight, and calculation method to avoid wastage and ensure strong reinforcement cages.

---

2: What is Binding Wire?

Binding wire is annealed mild steel wire used to tie reinforcement bars in reinforced cement concrete (RCC) work. It is soft, flexible, and does not break during twisting.

👉 Binding wire is also called “Annealed Binding Wire” or “MS Binding Wire”.

---

3: Standards for Binding Wire

• IS 2502: Code of Practice for Bending and Fixing of Bars for Concrete Reinforcement

  • Specifies binding wire use for tying rebars.

• IS 280: Mild Steel Wire for General Engineering Purposes

  • Specifies manufacturing, sizes, and properties of annealed mild steel wire.

👉 As per IS 2502, binding wire should be annealed mild steel wire of 16 to 22 gauge depending on bar size.

---

4: Common Sizes and Weight of Binding Wire

SWG (Wire Gauge)	Diameter (mm)	Weight (kg/m)	Length per kg (m)	Typical Use
22	0.7	0.0030	~333 m/kg	Slabs, light bars
20	0.9	0.00499	~200 m/kg	Slabs, beams
18	1.2	0.00888	~113 m/kg	Beams, columns
16	1.6	0.01578	~63 m/kg	Heavy bars, pile caps

---

5: How to Calculate Binding Wire

H3: Method 1 – Quick Rule (Per Tonne of Steel)

A simple rule used on construction sites:

Wire (kg) = Steel weight (tonnes) × 9 – 13

• Take 12 kg/tonne as safe average.
• Add 5–8% wastage.

Example:
Steel = 2.5 tonnes

Wire = 2.5 × 12 = 30 kg
Add 6% wastage → Final = 32 kg binding wire

---

6: Method 2 – Tie Count (More Accurate)

Step 1: Count number of ties
Nties = Total number of tie points

Step 2: Average tie length
Ltie = 0.12 – 0.30 m (depending on bar size)

Step 3: Total wire length
Ltotal = Nties × Ltie

Step 4: Wire mass per metre
m per m = (π ÷ 4) × (dmm ÷ 1000)² × 7850

Step 5: Total wire mass
M = Ltotal × m per m

Step 6: Add wastage (5–8%)

Example:

• Ties = 5000
• Tie length = 0.18 m
• Wire dia = 1.2 mm

Ltotal = 5000 × 0.18 = 900 m
m per m = 0.008878 kg/m
M = 900 × 0.008878 = 7.99 kg
Add 6% wastage → Final = ~9 kg (nearest coil 10 kg)

---

7: Tests for Binding Wire (IS 280)

• Tensile test – check minimum tensile strength.
• Wrap test (bend test) – wire should bend without breaking.
• Diameter check – confirm with micrometer/vernier.
• Visual inspection – no rust, cracks, or uneven thickness.

---

8: Quick Tips for Site Engineers

• For 1 tonne of steel → keep 12 kg binding wire ready.
• Always choose annealed (soft) wire for easy twisting.
• Store in dry place to avoid rust.
• Order in coils of 5, 10, or 20 kg depending on site need.

---

H2: Conclusion

Binding wire is small but plays a big role in reinforcement work. By knowing the correct size, weight, IS standards, and calculation methods, engineers and supervisors can save cost, reduce wastage, and ensure strong RCC construction.