Civil and Structural Engineering Calculators
These calculators handle the structural checks and quantity take-offs that come up on every civil and building project: how far a beam deflects, what the shear and bending moment diagrams look like, when a column buckles, the moment of inertia of a section, how much a steel member weighs, how many reinforcing bars a slab needs and how much cement, sand and aggregate a mix takes.
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All Civil & Structural (11)
Beam Deflection Calculator
Maximum deflection and slope of simply supported and cantilever beamsShear and Bending Moment Calculator
Shear force and bending moment diagrams for beams with point and distributed loadsColumn Buckling Calculator
Euler critical buckling load and slenderness for columns with different end conditionsSection Properties Calculator
Area, centroid, moment of inertia and section modulus of common cross-sectionsSteel Weight Calculator
Weight of steel plates, bars, tubes, angles and beams by size and lengthRebar Calculator
Number, length and weight of reinforcing bars for a slab or footingConcrete Mix Ratio Calculator
Cement, sand, aggregate and water quantities for a nominal concrete mixBrick and Mortar Calculator
Bricks or blocks and mortar needed for a wall, with openings and wasteAsphalt Calculator
Tons of asphalt for a driveway or paving area from size and thicknessCut and Fill Calculator
Earthwork volumes from a grid of existing and proposed levelsCoordinate Distance Calculator
Distance and bearing between two latitude/longitude points
Which tool do I need?
Draw shear and bending moment diagrams for a beam
Add the supports and loads to get reactions, maximum shear and moment, and the diagrams.
Find the moment of inertia of an I-beam
Enter the flange and web dimensions to get Ix, Iy, section modulus and radius of gyration.
Work out how much rebar a slab needs
Enter the slab size, bar size and spacing each way to get the bar count, total length and weight.
Estimate cement bags for a 1:2:4 mix
Pick the mix ratio and volume to get cement bags, sand and aggregate, and the water for a chosen water-cement ratio.
About Civil & Structural
Site quantities are covered too. Estimate bricks or blocks and mortar for a wall, tons of asphalt for a driveway, cut and fill volumes from a level grid, and the distance and bearing between two GPS coordinates. Results come with the formula, the assumptions and the units used.
Results are for checking, learning and preliminary design. Anything that carries load, current, pressure or people must be confirmed by a qualified engineer or licensed tradesperson against the code that governs your project.
Guides
- Beam Deflection Formulas: Where 5wL⁴/384EI Comes From and When L/360 AppliesHow the standard beam deflection formulas are derived, what E and I really control, which deflection limits the codes set, and the mistakes that make a beam bounce.
- How to Draw Shear Force and Bending Moment Diagrams, Step by StepReactions from equilibrium, the cut-and-sum method, the dV/dx and dM/dx rules, sign conventions, overhangs and cantilevers, with fully worked numbers.
- Column Buckling Explained: Euler, K Factors, Slenderness and the Johnson ParabolaWhy slender columns fail below yield, how effective length factors work, where Euler stops being valid, and how the AISC column curve compares.
- Moment of Inertia, Section Modulus and Radius of Gyration for EngineersWhat each section property means, how to calculate centroids and the parallel axis theorem by hand, elastic versus plastic modulus, and the unit traps.
Frequently asked questions
What deflection limit should a floor beam meet?
L/360 under live load is the common limit for floors with brittle finishes, with L/240 for total load. Roofs and other members often use L/180 or L/240. Your building code sets the actual limits.
Why is the dry volume of concrete about 1.54 times the wet volume?
Dry cement, sand and aggregate contain voids that the paste fills when mixed, and some material is lost. Multiplying the wet volume by about 1.54 gives the dry ingredient volume to order.
When does the Euler buckling formula stop being valid?
When the critical stress it predicts is above the material's proportional limit, which happens for short, stocky columns. The column buckling calculator switches to the Johnson parabola in that range.
How accurate is the haversine distance between coordinates?
It treats the Earth as a sphere, so it can be off by up to about 0.5%. The Vincenty method on the WGS-84 ellipsoid is accurate to millimetres and is shown alongside.