Category
Civil Engineering
Civil engineering formulas and calculators for structural, geotechnical, and hydraulic design used in buildings, foundations, and infrastructure. Includes load analysis, soil mechanics, and fluid flow equations.
32Formulas
3Subcategories
Updated Jul 2026
General
Construction Cost Estimate per Area
Cost = Built-up Area * Rate per Area
General
Building Floor Area Ratio (FAR)
FAR = Total Floor Area / Plot Area
General
Plot Area from Length and Width
A = L * W
General
Land Area Unit Conversion (Acres to Square Feet)
Area (sq ft) = Area (acres) * 43,560
General
Fence/Perimeter Length Calculation
P = 2*(L + W)
General
Drainage Pipe Slope
Slope (%) = (Elevation Drop / Pipe Length) * 100
General
Manning's Equation (Open Channel/Pipe Flow)
V = (1/n) * R^(2/3) * S^(1/2)
Geotechnical
Retaining Wall Factor of Safety Against Overturning
FS = Resisting Moment / Overturning Moment
Structural
Beam Deflection (Simply Supported, Center Point Load)
δ = P*L³ / (48*E*I)
Structural
Simple Column Axial Load Capacity
P = 0.4*fck*Ac + 0.67*fy*Asc
Structural
Steel Reinforcement (Rebar) Weight
W = (D² / 162) * L
Geotechnical
Trench/Excavation Volume
V = L * W * D
General
Rainwater Harvesting Potential
V = A * R * C
General
Water Tank Storage Capacity
V = L * W * H
General
Percent Slope to Degrees Conversion
θ = arctan(Slope % / 100)
General
Road/Ramp Gradient Percentage
Gradient (%) = (Rise / Run) * 100
Structural
Roof Pitch (Rise over Run)
Pitch = Rise / Run
Structural
Staircase Rise-to-Run Ratio
2R + T = 600 to 640 mm (comfort rule)
General
Plaster Quantity for a Wall
V = Wall Area * Plaster Thickness
General
Flooring Tile Quantity
N = (Floor Area * (1 + Wastage %)) / Tile Area
General
Paint Quantity Required
Paint (L) = (Wall Area * Number of Coats) / Coverage Rate
General
Number of Bricks for a Wall
N = Wall Volume / (Brick Volume + Mortar Allowance)
General
Cement Bags Required for Concrete
Bags = (Cement Volume * Cement Density) / Bag Weight
General
Concrete Mix Quantity (Cement-Sand-Aggregate)
Material Volume = (Ratio Part / Sum of Ratio Parts) * Total Dry Volume
General
Concrete Volume for a Slab
V = L * W * T
General
Gyroscopic Precession Rate
Ω_p = M / (I * ω_s)
General
Glide Ratio
Glide Ratio = L/D = Horizontal Distance / Altitude Lost
Hydraulics
Manning's Equation
V = (1/n)R^(2/3)S^(1/2)
Geotechnical
Bearing Capacity of Soil
q_u = cN_c + qN_q + 0.5γBN_γ
Structural
Shear Stress in a Beam
τ = VQ / Ib
Structural
Euler's Buckling Load
P_cr = π²EI / (KL)²
Structural
Bending Stress in a Beam
σ = M·y / I