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Free online doubly reinforced beam design calculator by limit state method. This calculator will calculate main steel as well as deflection check of beam.


  1. This calculator is intended for educational purpose only.
  2. Any unwarranted use or commercial use on site should be checked by a qualified engineer.
  3. As much as we take utmost care to design our calculators to give accurate results, DCBA Online site does not take responsibility of the results.
  4. For singly reinforced beam design check out this calculator.


What is doubly reinforced beam

A doubly reinforced beam is a beam reinforced with steel in both compression and tension zones.

Design of doubly reinforced beam by limit state method are recommended when the depth of the beam is limited due to architectural reasons and enough compression zone cannot be achieved for the given beam.

In such cases it becomes essential that the compression zone of concrete is required to be strengthened, and hence the steel is provided in compression zone also.

Design of doubly reinforced beam by limit state method are recommended only when the given beam dimensions are not able to resist the given ultimate moment, hence the maximum moment of resistance of the beam is checked before designing it as doubly reinforced section.

How to use calculator:

Quantities with ‘*’  marks are essential and without these the calculations will not be performed.

The width ‘B’ and the limiting depth ‘D’ has to be entered as a required value. 

Type of beam will determine the deflection limits.

Concrete grade and steel grade are also required quantities, steel grade can be chosen from dropdown list and three grade options are available 250, 415 and 500.

Exposure conditions will determine the nominal cover requirements.

Loading has to be entered as maximum ultimate moment, as this calculator is programmed only for flexure design of doubly reinforced sections.

In the result section, all the values are automatically calculated by the program with some values being editable by the user.

Nominal cover, effective cover and effective depth all are auto calculated but user has the option to specify them manually as well.

Since this program does not design beams for shear design, the stirrup diameter has to be manually input by the user.

For main steel, the program will give the best possible diameter, however the user is free to choose from different diameter options available from drop down list.

Deflection check for doubly reinforced beam design will be performed only if the length is specified. Also if the modification factor for tension comes greater than 2 and for compression if it comes greater than 1.5 then the deflection check will not be performed.

Doubly reinforced beam design will only be performed if the limiting depth is not able to provide maximum moment of resistance, in case where singly reinforced beam is possible, the calculator will design the beam as singly reinforced beam.

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