Example Data Table
| Opening |
Width |
Trial Depth |
Bearing |
Masonry Height |
Typical Use |
| 1.20 m |
150 mm |
200 mm |
150 mm |
0.60 m |
Small internal door |
| 1.80 m |
200 mm |
250 mm |
150 mm |
0.90 m |
External door or window |
| 2.40 m |
230 mm |
350 mm |
200 mm |
1.20 m |
Wider opening |
Formula Used
Effective span: lesser of clear span plus effective depth, or center to center bearing span.
Self weight: lintel width × lintel depth × concrete density.
Masonry line load: masonry density × wall thickness × effective masonry height.
Ultimate line load: dead load factor × dead load plus variable load factor × variable load.
Beam moment: simply supported loads are checked using equilibrium reactions and maximum bending location.
Bending capacity: φMn = φAsfy(d − a/2), where a = Asfy ÷ (0.85fckb).
Shear capacity: φVc = φ × 0.17 × √fck × b × d.
Deflection: service deflection uses gross inertia, elastic concrete modulus, uniform load, and optional point load.
How To Use This Calculator
Enter the clear span first. Add bearing length, wall width, and a trial depth. Then enter concrete strength, steel strength, cover, bar size, and bar count. Add masonry height and load data. Choose whether arching should limit masonry height. Press the calculate button. Review ratios below one as preliminary passes. Download the CSV or PDF for records.
Concrete Lintel Sizing Guide
A concrete lintel carries masonry, finishes, and other loads across an opening. It works like a short beam. The top fibers compress. The bottom steel resists tension. Good sizing starts with a clear span, a realistic wall load, and enough bearing at each end.
Why Load Checks Matter
Openings change the load path in a wall. Brick, block, render, and supported framing may push down on the lintel. A narrow lintel can crack. A shallow lintel can deflect. Poor bearing can crush masonry near the jamb. This calculator helps compare these risks before drawings are finalized.
Service And Ultimate Values
Service load describes normal use. It is useful for deflection checks. Ultimate load includes safety factors. It is used for bending, shear, and bearing checks. The tool separates dead weight from added loads. That makes the result easier to review.
Important Input Choices
Wall thickness usually sets lintel width. Overall depth controls stiffness. Cover and bar size reduce effective depth. Bearing length affects support pressure. Masonry height affects the line load. When arching is allowed, the effective masonry height may be limited by the span.
Reading The Result
The result shows effective span, total load, reaction, moment, shear, deflection, reinforcement area, and capacity ratios. Ratios below one usually mean the trial section passes that simplified check. Ratios above one suggest a larger lintel, more steel, longer bearing, or a detailed design review.
Use Sensible Limits
Every project has its own code, material grade, restraint, exposure, and workmanship assumptions. The calculator uses simplified beam physics. It does not replace a licensed structural engineer. Use it for early sizing, comparison, education, and checking obvious mistakes. Final lintels should match local standards and approved construction documents.
Practical Design Notes
Increase depth before adding excessive steel. Depth improves stiffness and bending resistance. Keep bars well covered. Check that reinforcement can fit with spacing rules. Confirm that the lintel width matches the wall leaf. For cavity walls, separate leaves may need separate lintels. Always consider temporary support during installation. Record assumptions with each estimate. Small changes in density, span, or bearing can change the answer. Compare more than one section before ordering units. Keep notes with drawings for future reviews too.
FAQs
What is a concrete lintel?
A concrete lintel is a beam placed over an opening. It carries wall loads to the supports at both sides. It is often reinforced because concrete is weak in tension.
Can this calculator give final structural approval?
No. It gives simplified sizing checks for early review. Final approval should come from a qualified engineer who can apply local codes, detailing rules, and site conditions.
What span should I enter?
Enter the clear opening between supports. The calculator estimates effective span using clear span, effective depth, and bearing distance. This follows common beam sizing practice.
Why does bearing length matter?
Bearing length spreads reaction force into the wall. Short bearing can create high local stress. Longer bearing often improves support safety, if the masonry is sound.
What does masonry arching mean?
Masonry arching assumes only part of the wall above the opening loads the lintel. The calculator limits effective masonry height to half the span when this option is selected.
Which result is most important?
Review all ratios. Bending, shear, bearing, deflection, and span-depth checks can each control sizing. A safe-looking bending result does not guarantee a good lintel.
How can I reduce deflection?
Increase the lintel depth first. Depth greatly increases stiffness. You can also reduce span, reduce load, improve restraint, or use a stronger engineered section.
Why is reinforcement area shown?
Reinforcement area helps compare provided steel with estimated demand. It also shows whether the selected bar count and diameter are reasonable for the trial section.