TryBuildCalcStirrup Cutting Length CalculatorRectangular stirrup and link estimator
Build a bar bending schedule with cutting length, bend/hook deductions, and total weight.
🕒 Last updated: August 11, 2026
Global Settings
ℹ️Applied at both ends of every stirrup/ring hook — commonly 9× diameter, confirm against your applicable code.
Cost
Bar Marks
This schedule needs approximately 11.6 kg (0.012 tonnes) of reinforcement steel across 1 bar mark.
| Bar Mark | Member | Shape | Dia (mm) | Bars/Member | Members | Cutting Length (m) | Total Length (m) | Unit Wt (kg/m) | Total Wt (kg) |
|---|---|---|---|---|---|---|---|---|---|
| S1 | Beam | Rect. Stirrup | 8 | 20 | 1 | 1.472 | 29.44 | 0.395 | 11.63 |
Summary by Diameter
8mm — 20 bars, 29.4 m total: 11.6 kg
Grand Total
Total Bars: 20
Total Length: 29.4 m (97 ft)
Total Weight: 11.6 kg (0.012 tonnes)
Assumptions Used
Unit weight: d² ÷ 162 (kg/m) | Bend deduction: 1d/2d/3d at 45°/90°/135° | Hook length factor: 9d
Not sure why cutting length is shorter than the outer dimensions? Bar Bending Schedule (BBS) Guide →
Bar Shape Reference
Diagram simplified for clarity (not to scale). Illustrative only.
See the complete Bar Bending Schedule Calculator guide for the full formula walkthrough, verification checklist, and FAQ.
Rectangular stirrup cutting length estimate
This page pre-fills a rectangular stirrup row: cutting length = 2 × (inside width + inside depth) + 4 × diameter (converting inside dimensions to a centerline perimeter), minus four 90° corner bend deductions, plus a hook allowance at both ends.
Measure width and depth as the inside dimension against the main bars, not the outside dimension of the concrete section — this is the single most common stirrup measurement mistake.
- Centerline perimeter = 2 × (Inside Width + Inside Depth) + 4 × Diameter.
- Four 90° corner bends are deducted (2 × diameter each) from the centerline perimeter.
- Hook allowance (2 × hook length factor × diameter) is added when "Include Hook" is enabled.
How Is Cutting Length Calculated?
Every bar mark follows the same overall sequence — calculate the shape's raw geometric length, subtract bend deductions, add any hook allowance, then add one lap length if a splice is included — but the raw-length formula itself differs by shape.
Step 1 — Raw Length by Shape
Straight = Length (A)
L-Bend = Leg A + Leg B
Rect. Stirrup = 2 × (Inside Width + Inside Depth) + 4 × Diameter
Circular Ring = π × Ring Diameter
Cranked = Straight A + (Rise ÷ sin(Bend Angle)) + Straight C
The rectangular stirrup and circular ring shapes are closed loops measured around their perimeter or circumference; the stirrup's inside width and depth are converted to a centerline perimeter by adding 4 × diameter (the bar sits half a diameter outward from the inside face on each of the four sides) before any bend deduction is applied. The cranked shape's inclined segment length is derived from the vertical rise and the bend angle using basic trigonometry.
Step 2 — Bend Deduction
Deduction per bend = 1 × diameter (45°), 2 × diameter (90°), 3 × diameter (135°)
L-Bend / Cranked: 1 bend (or 2 for cranked) deducted once each
Rect. Stirrup: 4 × 90° corner deductions
Steel compresses slightly on the inside of a bend, so the finished bar is shorter than the sum of its straight-line legs — this deduction corrects for that per bend in the bar.
Step 3 — Hook Allowance (Stirrups & Rings Only)
Hook Allowance = 2 × (Hook Length Factor × Diameter)
Applied once at each end of a stirrup or ring's open loop before it's closed — not applicable to straight, L-bend, or cranked shapes.
Step 4 — Lap Length (Optional)
Cutting Length = Raw Length − Bend Deduction + Hook Allowance + (Lap Multiplier × Diameter, if included)
Include a lap length only for a bar mark that splices onto another bar of the same mark to exceed one stock length.
Step 5 — Total Length and Weight
Total Bars = Bars per Member × Number of Members
Total Length = Cutting Length × Total Bars
Unit Weight (kg/m) = Diameter² ÷ 162
Total Weight (kg) = Total Length × Unit Weight
The diameter² ÷ 162 formula is the standard basis for reinforcement steel weight and is the same figure suppliers use for billing.
Worked Example (First Bar Mark)
This example walks through the first bar mark in your schedule above, using the same steps from the formula section — every other bar mark in the schedule follows the identical method.
Bar Mark Used: S1
| Input | Value |
|---|---|
| Shape | stirrupRect |
| Diameter | 8 mm |
| Bars per Member × Members | 20 × 1 = 20 bars |
Step 1-4 — Cutting Length
| Calculation | Substitution | Result |
|---|---|---|
| Shape length (after bend/hook deductions) | Per shape formula in Step 1-3 | 1.472 m |
| Final cutting length | Shape length − deductions + hooks/laps | 1.472 m (4.83 ft) |
Step 5 — Total Length and Weight
| Calculation | Substitution | Result |
|---|---|---|
| Total length | 1.472 × 20 | 29.44 m |
| Unit weight | 8² ÷ 162 | 0.395 kg/m |
| Total weight | 29.44 × 0.395 | 11.63 kg |
Therefore, bar mark S1 needs 20 bars cut to 1.472 m each, totalling 11.63 kg.
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Disclaimer: This calculator provides approximate results for planning and estimation purposes only. Actual requirements may vary based on site conditions, materials, workmanship, and local building regulations. Always consult a qualified engineer, architect, or construction professional before making final decisions.