TMT (thermo-mechanically treated) bars are the reinforcement in almost every concrete building in India. The grade printed on the bar tells you its minimum strength, and the right grade is set by your structural engineer, not by the dealer.
What the numbers mean
- Fe 415, Fe 500, Fe 550, Fe 600: the minimum yield strength in N/mm² as per IS 1786.
- D grades (Fe 500D, Fe 550D): tighter limits on carbon, sulphur and phosphorus and higher elongation, so the bar bends more before breaking. Preferred in seismic zones and for important structures.
- CRS / S grades: corrosion-resistant or special variants for specific conditions.
Check before you accept
- BIS licence number and grade rolled onto the bar at regular intervals.
- Mill test certificate (MTC) for the heat or lot, with chemical and mechanical results.
- Uniform ribs, no cracks or heavy rust scaling.
- Weight per metre within tolerance; weigh a few bars on large orders.
How steel is billed
TMT is usually sold by weight (per kg or per tonne), sometimes by bundle or piece for smaller sizes. Ask whether the quote is on actual weight or theoretical (sectional) weight, and whether cutting, bending, loading and freight are included.
Tip:Do not substitute a different grade or diameter from the drawings without your engineer's written approval. It changes the design.
Primary vs secondary producers
Both large integrated plants and smaller mills produce BIS-certified TMT. What matters is a valid BIS licence, consistent test results and traceable invoices.
Frequently asked questions
Is Fe 550D better than Fe 500D?
It is stronger, so designs can use less steel, but it must be designed for. Use the grade your structural engineer specified.
What is the weight of a 12 mm bar?
Approximately d²/162 kg per metre, so about 0.89 kg/m for 12 mm. A 12 m length weighs about 10.7 kg.
Why is there a rate difference between brands?
Raw material route, brand reach, testing and service differ. Compare BIS grade, MTC and delivered rate rather than brand alone.
This article is general information, written in November 2026, and is not legal, tax or financial advice. Rules, rates and limits change; please confirm the current position with the authority concerned or a qualified professional before you act.
