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Rebar Weight and Procurement Calculator

Estimate reinforcing-bar unit mass, procurement length, whole stock bars, purchased mass, tie wire, material cost, and handling bundles.

Nominal bar diameter (mm)Installed bar length (m)Waste and lap allowance (%)Stock bar length (m)Steel price per kgTie-wire allowance as steel weight (%)Bundle handling capacity (kg)

Nominal mass per metre (kg/m)-

Length including waste and laps (m)-

Whole stock bars-

Purchased stock length (m)-

Purchased rebar mass (kg)-

Tie-wire planning allowance (kg)-

Modeled rebar cost-

Whole handling bundles-

Decision view

Rebar cross-section, mass curve, and stock plan

Rebar cross-section, mass curve, and stock planDiameter drives a quadratic kg/m curve while allowance and whole-stock rounding build purchased length, mass, and bundles.

Exact scenario comparisonNominal bar diameter (mm) changes while all other entered assumptions remain constant.

Nominal bar diameter (mm)	Nominal mass per metre (kg/m)	Length including waste and laps (m)	Whole stock bars	Purchased stock length (m)	Purchased rebar mass (kg)	Tie-wire planning allowance (kg)	Modeled rebar cost	Whole handling bundles

How to use Rebar Weight and Procurement Calculator

Enter nominal bar diameter and installed length.
Enter lap/waste allowance and stock-bar length.
Enter mass price, tie-wire percentage, and bundle capacity.
Review the diameter curve and stock-cut plan before ordering.

Calculator guide

Understanding Rebar Weight and Procurement Calculator

Rebar procurement starts with a diameter-dependent mass per metre, then adds lap and waste, rounds to whole stock bars, and converts purchased length to mass. This calculator shows each rounding and material state explicitly.

Diameter is quadratic Mass per metre follows d².

Allowance precedes rounding Required length is increased first.

Bars are whole Stock count uses a ceiling.

Purchased mass drives cost Rounding is retained in the bill.

Calculation method

How the calculation works

Use the common metric nominal mass relationship d²/162, gross installed length for laps and waste, and round procurement to whole stock bars. Use the standard d²/162 metric mass approximation, apply the allowance to installed length, round up to whole stock bars, and price the purchased mass.

Detailed calculation process

Convert bar diameter and installed length into a whole-stock procurement plan

The defaults use 16 mm bar, 850 m installed length, 12% lap and waste, and 12 m stock bars.

General formula: w = d²/162; L_req = L_inst(1+a); N = ceil(L_req/L_stock); L_buy = NL_stock; M = wL_buy; M_tie = f_t M; Cost = pM Bar mass grows with diameter squared. The length allowance is applied before stock rounding, and mass and cost use purchased—not merely installed—length.

What each symbol means

d / w Nominal diameter in mm and approximate unit mass in kg/m.

L_inst / a Installed length in m and lap/waste fraction.

L_stock / N Stock-bar length in m and whole number of bars.

L_buy Purchased bar length after stock rounding, in m.

M / M_tie Purchased rebar and tie-wire masses, in kg.

p / Cost Price per kg and resulting material cost.

Worked substitution with the default inputs

1. Calculate unit mass: w = 16²/162 = 1.580247 kg/m Doubling diameter would quadruple this approximate mass per metre.

2. Add lap and waste length: a = 12/100 = 0.12; L_req = 850×1.12 = 952.000 m The allowance is applied to installed length before stock rounding.

3. Round to whole stock bars: N = ceil(952/12) = 80 bars; L_buy = 80×12 = 960 m Eight metres remain above the allowance-adjusted requirement.

4. Convert purchased length to mass: M = 960×1.580247 = 1,517.037 kg; M_tie = 0.015×1,517.037 = 22.756 kg The entered tie-wire factor is 1.5% of purchased rebar mass.

5. Check cost and handling: Cost = 1,517.037×1.25 = 1,896.30; bundles = ceil(1,517.037/1,500) = 2 Both procurement cost and handling use the rounded purchase mass.

The default plan buys 80 twelve-metre bars, or 960 m and 1,517.037 kg of rebar, plus 22.756 kg of tie wire, across two modeled handling bundles.

Steel procurement

Connect bar diameter to stock and bundle consequences

The visual combines a scaled cross-section, d² mass curve, and whole-bar purchase strip.

Cross-section Nominal diameter controls area and mass.

Mass curve Unit mass rises quadratically.

Stock strip Required length rounds to whole bars.

Handling Purchased mass determines bundle count.

Worked situations

Practical examples

A 16 mm bar is approximated at 1.580247 kg/m.
The 12% allowance raises 850 m to 952 m.
Whole-stock rounding produces 80 bars and 1,517.037 kg.

Better inputs

Useful tips

Use bar schedules by diameter rather than averaging mixed sizes.
Check supplier nominal mass and available stock lengths.
Separate couplers, hooks, chairs, fabrication, and freight if required.

Before relying on the result

Limitations and common mistakes

The d²/162 expression is a common metric approximation.
Bend deductions, shape codes, offcut reuse, bar marks, corrosion, coatings, and fabrication tolerances are excluded.
Structural detailing and code compliance require an approved reinforcement schedule.

Reference

Key terms

Unit mass: Mass of one metre of a selected bar diameter.
Lap allowance: Extra length for overlaps and procurement waste.
Stock bar: Standard supplied straight length.

Important note

Calculated from the entered measurements and stated coverage or quantity rules. Confirm field dimensions, waste, product requirements, structural conditions, and local codes before purchasing or building.

Frequently asked questions

Why use d squared?

Steel area and therefore mass per metre scale with circular cross-sectional area.

Why calculate mass from purchased length?

The supplier charges for whole purchased stock, including rounding surplus.

Does tie wire count affect bar mass?

No. It is reported as a separate percentage-based mass.

Can this replace a bar bending schedule?

No. It is a bulk procurement estimate.