Rebar — also called reinforcing bar or concrete steel — is the steel bar used to strengthen concrete structures in construction. Concrete resists compression well but is weak in tension; rebar covers that weakness, and the combination (reinforced concrete) forms the backbone of almost every modern structure: houses, high-rise buildings, bridges, and dams.

As a steel mill that has produced rebar for more than 50 years, Inter World Steel has put together this guide to help you understand, calculate, and choose the right rebar for your project.

Types of Rebar: Plain and Deformed

Plain Rebar (BjTP)

Smooth surface with an even, round cross-section. Because it bends easily, plain rebar is commonly used for stirrups and ties — the binding rings around columns and beams — as well as distribution reinforcement in floor slabs. The common grade is BjTP 280.

Deformed or Ribbed Rebar (BjTS)

Its surface carries transverse ribs that lock the bar into the concrete, giving it far stronger bonding than plain rebar. This is what serves as main reinforcement in columns, beams, foundations, and every load-bearing structural element. Available in grades BjTS 420, BjTS 520, and BjTS 550.

For a closer look at when to use each type, read our article on the difference between plain and deformed rebar.

Grades Under SNI 2052:2024

SNI 2052:2024 is the Indonesian national standard governing concrete reinforcing steel, covering dimensions, tolerances, mechanical properties, and marking. The number in each grade name indicates the minimum yield strength in megapascals (MPa):

  • BjTP 280 — plain bar, minimum yield strength 280 MPa
  • BjTS 420 — deformed bar, minimum yield strength 420 MPa, with ductility requirements for earthquake-resistant construction
  • BjTS 520 — high-strength deformed bar, minimum yield strength 520 MPa
  • BjTS 550 — highest-grade deformed bar, minimum yield strength 550 MPa, for long-span bridges and tall buildings

The higher the grade, the greater the load a bar of the same diameter can carry — which means the total volume of steel can be reduced in heavily loaded structures.

Rebar Size and Weight Table (SNI)

Rebar is sold per bar at a standard length of 12 metres. Nominal weight follows the standard formula:

Weight (kg/m) = 0.006165 × d²  (d = nominal diameter in mm)

Diameter Weight per metre Weight per bar (12 m) Available as
8 mm 0.395 kg 4.73 kg Plain & Deformed
10 mm 0.617 kg 7.40 kg Plain & Deformed
12 mm 0.888 kg 10.65 kg Plain
13 mm 1.042 kg 12.50 kg Deformed
16 mm 1.578 kg 18.94 kg Plain & Deformed
19 mm 2.226 kg 26.71 kg Deformed
22 mm 2.984 kg 35.81 kg Plain & Deformed
25 mm 3.853 kg 46.24 kg Plain & Deformed
29 mm 5.185 kg 62.22 kg Deformed
32 mm 6.313 kg 75.76 kg Plain & Deformed
36 mm 7.990 kg 95.88 kg Deformed
40 mm 9.864 kg 118.37 kg Deformed

The weights above are nominal values calculated to SNI. Actual weight may vary within the tolerances the standard allows — but a bar falling well below nominal is a sign it does not meet SNI. Per-diameter tolerances are listed on our Product Specification page.

How to Calculate Your Rebar Requirement

Using the table above, the steel needed for a structural element can be worked out in three steps:

  1. Total the bar length. Add up every bar length required by the drawings, including lap splices and bends.
  2. Multiply by weight per metre. Take the figure from the second column for the diameter you are using.
  3. Divide by weight per bar. The result is the number of 12-metre bars to order, rounded up.

Example: a column requires 8 main bars of D16 at 4 metres each, so 32 metres in total. Total weight is 32 × 1.578 = 50.5 kg. Since one D16 bar weighs 18.94 kg, you need 50.5 ÷ 18.94 = 2.7 bars — rounded up to 3 bars.

For a whole-building take-off, add roughly 5–10 per cent as an allowance for offcuts and bending.

Telling Genuine SNI Rebar from Undersized Bars

Undersized rebar — known locally as besi banci — is steel whose actual diameter is smaller than the label claims, for instance sold as D13 when it is really 12 mm. That small difference cuts structural capacity significantly, because cross-sectional area falls much faster than diameter. Signs of genuine SNI rebar:

  1. Raised mill marking on the bar showing the mill initials, diameter, and steel grade
  2. Actual diameter matches the label when measured with a caliper
  3. Weight per bar matches nominal — compare against the table above
  4. Supplied with SPPT-SNI and a mill certificate covering tensile test, bend test, and chemical composition

The most practical field check is simply to weigh it. Weight cannot be faked: if a D16 bar comes in well under 18.94 kg, something is wrong.

What Determines the Price of Rebar

Rebar pricing is driven by global raw material costs (scrap and billet), bar diameter and type, grade, and the length of the distribution chain. Buying direct from the mill is generally more competitive because it cuts out intermediaries — and it gives certainty of quality, since every bar can be traced through its mill certificate.

Tips for Choosing Rebar for Your Project

  1. Match the grade to the structural design; never substitute a grade lower than the engineer specified
  2. In earthquake-prone areas, use BjTS 420 or above, which meets the ductility requirements
  3. Always request the SNI certificate and mill certificate before delivery
  4. Check the marking and measure the diameter on arrival, not after installation
  5. Buy from a mill or an authorised distributor with a clear track record

Frequently Asked Questions

What is the standard length of a rebar?

12 metres. Other lengths are available by special order.

What does the number in BjTS 420 mean?

It indicates the minimum yield strength of the steel in megapascals. BjTS 420 means deformed reinforcing bar with a minimum yield strength of 420 MPa.

How much does one D16 rebar weigh?

18.94 kg for a 12-metre bar, based on a nominal weight of 1.578 kg per metre.

Can plain rebar be used as main reinforcement?

It is not recommended. Plain bar bonds to concrete far less effectively than deformed bar, so its use is limited to stirrups and distribution reinforcement.

How can I be sure rebar is genuinely SNI-certified?

Check the raised marking on the bar, measure its actual diameter, weigh it, and ask the seller for the SPPT-SNI and mill certificate.

Buy SNI-Certified Rebar Direct from the Mill

Inter World Steel Mills Indonesia is a steel mill in Tangerang producing plain and deformed rebar certified to SNI 2052:2024, with more than 50 years of manufacturing behind it, serving contractors, distributors, hardware retailers, and national infrastructure projects. Every bar is guaranteed for size, weight, and grade, and comes with full documentation. See our certifications or explore our Premium Rebar line.

Contact our sales team through the Order Now page for factory-direct rebar pricing.