Use this free rebar TMT weight calculator to instantly find the weight of TMT bars, reinforcement bars, and round steel rods — from 6mm to 40mm diameter.
Simply select your bar diameter, enter the length and number of bars — the calculator instantly returns weight per meter, weight per bar, total weight, and bars per tonne.
Formula used: Weight = (π/4) × Diameter² × Length × Density
Rebar & TMT Bar Weight Calculator
Instantly calculate TMT / rebar weight per meter, per bar, and total weight — plus bars per tonne.
12mm TMT Bar — 12m length
Formula used: Weight = (π/4) × Diameter² × Length × Density (equivalent to the common D²/162.2 shortcut for standard steel density)
Table of Contents
How the Rebar & TMT Bar Weight Calculator Works
This rebar tmt weight calculator uses the same principle as any round steel bar calculation: cross-sectional area multiplied by length and material density. Since rebar is solid (not hollow like pipe), the formula is simpler than pipe or tube calculations.
The Formula
Weight (kg/m) = (π/4) × Diameter² × Density
Where Diameter is in meters and Density is in kg/m³.
Example: A 12mm TMT bar (Diameter = 0.012m, Density = 7850 kg/m³) weighs approximately 0.888 kg per meter — matching the standard industry reference value used across construction sites.
The D²/162.2 Shortcut
In practice, many site engineers and contractors use a simplified shortcut formula instead of the full density calculation:
Weight (kg/m) = Diameter² ÷ 162.2
Here, Diameter is in millimeters. This shortcut gives the same result as the full formula above — it's just a pre-combined constant for standard steel density (7850 kg/m³), rounded for quick manual use. This calculator uses the full precise formula internally, so results match or slightly improve on the 162.2 shortcut.
Standard TMT Bar Density
| Material | Density |
|---|---|
| Standard TMT / Mild Steel Rebar | 7850 kg/m³ |
(Note: Rebar grade — Fe415, Fe500, Fe500D, Fe550 — affects strength, not density, so all standard grades use the same 7850 kg/m³ value.)
Why Use This Rebar & TMT Bar Weight Calculator
Buying TMT bars usually works like this: you order by length (feet or meters), but the supplier bills you by weight (kg or tonnes). Without a quick way to verify weight, it's easy to get overcharged or under-ordered without realizing it.
- 12 standard diameters built-in — from 6mm to 40mm, covering every common TMT size used in residential and commercial construction
- Custom diameter option — for non-standard bars or imported steel sizes
- Bars per tonne calculation — instantly see how many bars make up one tonne, useful for bulk ordering and billing verification
- Bulk quantity support — calculate total weight for multiple bars in one go, not just a single piece
- Metric and Imperial support — switch between mm/m/kg and inch/ft/lb
- No login, no ads, no signup — just select your size and get your answer
- Export options — copy, save as image or PDF, or print for site records and quotations
Rebar Grades & Density Guide
Unlike other metals where density varies significantly by alloy, TMT rebar grades primarily differ in strength and ductility, not density. All standard grades use the same density for weight calculation purposes:
Fe 415 — The most basic grade, used in low-rise residential construction where load requirements are moderate.
Fe 500 — The most widely used grade today, offering a good balance of strength and ductility for general residential and commercial construction.
Fe 500D — Same strength as Fe 500 but with higher ductility (D = Ductile), preferred in earthquake-prone regions for better seismic performance.
Fe 550 / Fe 550D — Higher strength grades used in heavy-load structures like high-rises, bridges, and industrial buildings.
All these grades share the same density (7850 kg/m³) — so weight calculations remain identical regardless of grade. What changes between grades is the yield strength (measured in N/mm² or MPa), which determines how much load the bar can safely carry, not how much it weighs.
For official reinforcement standards and tolerances, refer to IS 1786:2008 on the Bureau of Indian Standards, which governs TMT bar manufacturing specifications across the region.
Who This Calculator Is Built For
This calculator is built for anyone who needs to verify or estimate rebar weight quickly, without manual math or guesswork:
- Site engineers & supervisors — verifying delivered steel weight against Bar Bending Schedule (BBS) requirements
- Contractors & builders — converting linear bar requirements into weight for supplier billing verification
- Homeowners building a house — checking that TMT bar weight matches what's being billed, to avoid being overcharged
- Steel suppliers & traders — providing quick weight estimates and bars-per-tonne figures to customers
- Civil engineering students — learning and verifying the D²/162.2 formula with real, instant calculations
- Procurement teams — planning bulk steel orders and calculating total tonnage requirements
Tips for Getting Accurate Results
Always use standard nominal sizes with this rebar tmt weight calculator for billing verification…
- Use nominal diameter, not measured diameter — TMT bars are billed by their nominal (catalog) size, even though actual measured diameter can vary slightly within IS tolerance limits. Use the standard size for billing verification.
- Confirm actual bar length before calculating — standard TMT bars are typically 12 meters (40 feet), but always confirm with your supplier, as lengths can vary.
- Grade doesn't affect weight — don't switch density values when comparing Fe 415 vs Fe 500 vs Fe 550; they all use the same 7850 kg/m³ density.
- Use "Bars per Tonne" to cross-check supplier bills — if a supplier's tonnage-to-bar-count doesn't match this calculator's figure, it's worth double-checking the actual bar count or length delivered.
- Add wastage allowance separately — this calculator gives theoretical weight only. Site wastage from cutting, bending, and laps (typically 5-10%) should be added separately in your budgeting.
- For non-standard sizes, use Custom Diameter — imported or older stock sometimes comes in sizes like 14mm or 18mm; use the custom diameter field for these.
Bookmark this rebar tmt weight calculator for repeated use on-site — no need to carry a printed chart or redo manual calculations for every delivery.
FAQs
How do I use a rebar tmt weight calculator to find TMT bar weight?
Multiply the cross-sectional area of the bar by its length and the density of steel. The formula is: Weight = (π/4) × Diameter² × Length × Density. For quick manual estimates, most site engineers use the shortcut formula Diameter² ÷ 162.2, where diameter is in millimeters.
What is the weight of a 12mm TMT bar per meter?
A standard 12mm TMT bar weighs approximately 0.888 kg per meter, based on standard steel density of 7850 kg/m³. A full 12-meter bar weighs approximately 10.66 kg.
Does rebar grade (Fe 415, Fe 500, Fe 550) affect its weight?
No. TMT bar grades differ in strength and ductility, not density. All standard grades use the same density (7850 kg/m³), so a 12mm Fe 415 bar and a 12mm Fe 500 bar weigh the same.
How many TMT bars make up one tonne?
This depends on the bar diameter and length. For example, a standard 12mm bar (12m length) weighs about 10.66 kg, meaning approximately 93 bars make up one tonne. This calculator shows the exact bars-per-tonne figure for any diameter and length you enter.
What is the standard length of a TMT bar?
TMT bars are typically manufactured and sold in 12-meter (approximately 40-foot) standard lengths, though this can vary slightly by manufacturer and region.
Can I calculate weight for non-standard rebar diameters?
Yes. While this calculator includes all standard diameters from 6mm to 40mm, you can also select "Custom diameter" to enter any non-standard size, such as imported steel or older stock.
Is this rebar weight calculator accurate for billing verification?
Yes, it uses the standard engineering formula and density used industry-wide. However, actual bar weight can vary slightly within manufacturing tolerances (per IS 1786:2008), so small variations between calculated and actual weight are normal and expected.
Is this rebar tmt bar weight calculator free to use?
Yes, this calculator is completely free, requires no login or signup, and has no usage limits.
What makes this rebar tmt weight calculator different from a manual chart?
Unlike a static chart, this rebar tmt weight calculator adjusts instantly for custom diameters, custom density, bulk quantities, and unit conversion — giving you exact figures instead of rounded chart values.
Quick Summary
This free rebar tmt weight calculator instantly calculates weight per meter, weight per bar, total weight, and bars per tonne for standard TMT bars from 6mm to 40mm diameter. Simply select your bar size, enter the length and quantity, and get accurate results in metric or imperial units — no login, no ads, no signup required. Whether you're a site engineer verifying delivered steel, a homeowner checking a supplier's bill, or a contractor planning a bulk order, this rebar weight calculator gives you instant, reliable results based on the standard D²/162.2 formula.
Disclaimer
The rebar tmt weight calculator and all information on this page are provided by BytePriva for general estimation and informational purposes only. While we strive for accuracy using standard engineering formulas and commonly accepted steel densities, actual weights may vary due to manufacturing tolerances (as permitted under IS 1786:2008 and equivalent standards), bar grade, surface ribbing, and supplier-specific specifications.
This tool is not a substitute for certified engineering calculations, official material test certificates (MTC), or professional structural design. Users are solely responsible for independently verifying all measurements, bar counts, and calculations before using them for purchasing, billing disputes, structural design, load-bearing applications, or any decision involving financial or safety-critical risk.
BytePriva, its owners, and contributors make no warranties, express or implied, regarding the accuracy, completeness, or reliability of this calculator or its results. To the fullest extent permitted by law, BytePriva shall not be held liable for any direct, indirect, incidental, or consequential loss, damage, injury, or cost arising from the use of, or reliance on, this calculator or the information provided on this page.
By using this calculator, you acknowledge and agree to these terms. For structural design, load calculations, or billing disputes involving significant value, please consult a licensed structural engineer or refer to your supplier's certified material test report.