Grade Reference
TMT Grade Comparison: Fe415 vs Fe500 vs Fe500D vs Fe550
All four standard IS 1786 grades compared side by side — mechanical properties, use cases, and which grade to specify for different building types and seismic zones.
IS 1786 mechanical properties
| Grade | Min yield (N/mm²) | Min UTS (N/mm²) | Min elongation | ||
|---|---|---|---|---|---|
Fe415 | 415 | 485 | 14.5% | ||
Fe500Most common | 500 | 545 | 12% | ||
Fe500DRecommended | 500 | 565 | 16% | ||
Fe550 | 550 | 585 | 10% | ||
| Source: IS 1786:2008 (High Strength Deformed Steel Bars and Wires for Concrete Reinforcement). UTS/YS ratio is theoretical minimum. | |||||
When to use each grade
Fe415
415 N/mm² yield · 14.5% elongation
Non-seismic zones only. Largely superseded by Fe500 for most uses.
Advantages
- ✓Slightly cheaper
- ✓Adequate for light non-structural use
Limitations
- –Lower strength means more steel required
- –Not permitted for seismic structures (IS 13920)
- –Phasing out in urban construction
Fe500
500 N/mm² yield · 12% elongation
Standard residential construction in seismic zones II and III.
Advantages
- ✓Industry standard — widest availability
- ✓Best price-to-strength ratio
- ✓Suitable for most G+0 to G+3 residential buildings
Limitations
- –UTS/YS ratio (1.09) may not meet IS 13920 ductile frame requirements in all batches
- –Not suitable for seismic zones IV/V structural use
Fe500D
500 N/mm² yield · 16% elongation
Mandatory for seismic zones III, IV, V (IS 13920). Recommended for all structural use.
Advantages
- ✓Higher ductility (16% elongation vs 12% for Fe500)
- ✓Meets IS 13920 UTS/YS ≥ 1.15 requirement reliably
- ✓Lower carbon = better weldability
- ✓Marginal price premium over Fe500
Limitations
- –Slightly higher cost than Fe500
- –May not be stocked at all dealers in Tier 2/3 cities
Fe550
550 N/mm² yield · 10% elongation
High-rise buildings, bridges, flyovers, pre-stressed structures.
Advantages
- ✓Highest yield strength in common grades
- ✓Reduces steel quantity for high-load structures
Limitations
- –Lower ductility (10% elongation)
- –Higher cost, limited availability
- –Requires careful detailing in seismic zones
Grade requirement by seismic zone
| Seismic zone | Risk level | Minimum grade (IS 13920) |
|---|---|---|
| Zone II | Low | Fe500 acceptable |
| Zone III | Moderate | Fe500D recommended |
| Zone IV | High | Fe500D mandatory |
| Zone V | Very high | Fe500D mandatory |
Per IS 13920:2016 (Ductile Design and Detailing). Always confirm your city's zone with your structural engineer. Full grade selection guide →
Frequently asked questions
What is the difference between Fe500 and Fe500D?
Both Fe500 and Fe500D have the same minimum yield strength (500 N/mm²), but Fe500D has higher ductility: 16% minimum elongation vs 12% for Fe500, and a higher UTS of 565 vs 545 N/mm². The 'D' suffix means enhanced ductility. Fe500D also has a lower maximum carbon content (0.25% vs 0.30%), making it more weldable and less brittle. IS 13920 (seismic design) recommends Fe500D for ductile reinforced concrete frames.
Which TMT grade is best for house construction in India?
For most residential construction in India, Fe500D is the recommended choice. It provides the same yield strength as Fe500 with significantly better ductility and weldability, at a small price premium. If your building is in seismic zone III, IV, or V — which covers most of peninsular India, the Himalayas, and the northeast — Fe500D is mandated by IS 13920.
Is Fe500D stronger than Fe500?
They have the same minimum yield strength (500 N/mm²). Fe500D has a higher minimum UTS (565 vs 545 N/mm²) and higher elongation (16% vs 12%), meaning it can absorb more energy before fracturing. In engineering terms, Fe500D is 'tougher' and more ductile; Fe500 has marginally the same elastic strength but less plastic deformation capacity.
When should I use Fe550 instead of Fe500D?
Fe550 is typically specified for structures where minimising steel weight is important (high-rise buildings, long-span bridges, pre-stressed members). Its higher yield strength allows engineers to use smaller bar diameters or fewer bars for the same load. However, its lower elongation (10%) makes it less suitable for seismic-critical connections without careful detailing.
Is Fe415 still used in India?
Fe415 is rarely specified for new construction in urban India. Most structural engineers now specify Fe500 or Fe500D, which provide better strength at a negligible cost difference. Fe415 may still appear in rural or informal construction, but it is not permitted for ductile frame design under IS 13920.
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