Civil Engineering Calculators
Last updated: October 2026
Pipe Flow Velocity Calculator
Calculates the average flow velocity of fluid in a circular pipe given a volumetric flow rate and pipe diameter.
Excavation Volume Calculator
Calculate the volume of earth to be removed for a rectangular excavation — foundation pit, trench, or basement cut.
Culvert Flow Capacity Calculator
Estimate the full-flow discharge capacity of a circular culvert using Manning's equation.
Pipe Flow Capacity Calculator
Determine water flow rate (in GPM) through circular pipes using Manning's equation.
Pipe Flow Rate Calculator
Determine the flow rate of water through a pipe using the Hazen-Williams equation.
Water Supply Pipe Sizing Calculator
Determine the minimum pipe diameter needed to deliver a required flow rate under specified pressure and elevation conditions.
Pipe Flow Calculator (Hazen-Williams)
Determine water flow rate and velocity in pressurized pipes using the Hazen-Williams empirical equation.
Soil Bearing Capacity Calculator
Estimate the ultimate bearing capacity of soil beneath a square footing with the general bearing-capacity equation in Terzaghi's square-footing form, using Prandtl–Reissner and Brinch Hansen bearing-capacity factors.
Structural Beam Load Calculator
Estimate the load-bearing stiffness of a simply supported structural beam based on its span, cross-section, and material.
Retaining Wall Design Calculator
Calculate active, passive, or at-rest lateral earth pressure on a retaining wall given soil properties, wall height, and surcharge loading.
Slope Stability Calculator
Compute the factor of safety against sliding failure on an infinite slope using soil strength and groundwater parameters.
Culvert Flow Calculator
Calculate the full-flow discharge capacity of a circular culvert using Manning's equation.
Flexible Pavement Thickness Calculator
Compute the required flexible pavement structural number using the AASHTO 1993 empirical design method.
Culvert Design Calculator
Size a circular or box culvert to pass a design stormwater discharge using Manning's equation.
Earthwork Excavation Calculator
Estimate the cost of a rectangular excavation from its length, width, depth and a price per cubic metre, plus the loose (swelled) volume and the number of truck loads to haul it away.
Manhole Volume Calculator
Calculates the volume of concrete required to construct a circular manhole wall given the outer diameter, inner diameter, and height.
Embankment Slope Stability Calculator (Infinite Slope, US Units)
Check whether a soil slope is safe against a shallow, planar slide by computing its factor of safety with the infinite-slope method, in US units (psf, pcf, feet).
Steel Reinforcement Calculator
Calculate the required tension steel reinforcement area (mm²) for singly reinforced concrete beams under a given design moment.
Flexible Pavement Design Calculator
Calculate the required asphalt pavement layer thickness based on traffic loading (ESALs), subgrade strength (CBR), design reliability, and climate zone using the AASHTO flexible pavement method.
Road Gradient Calculator
Calculates the gradient of a road or ramp as a percentage from the vertical rise and horizontal distance.
Culvert Sizing Calculator
Calculate the required culvert diameter to safely pass design stormwater flows under roads, driveways, or embankments.
Construction Cost Estimator
Make a quick order-of-magnitude budget for a slab, paving, foundation or other work priced per square foot: area × unit cost × a location factor, plus a contingency allowance.
Traffic Signal Timing Calculator
Determine the optimal signal cycle length and green time splits for a two-phase intersection.