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Calculators
Every tool on this page runs in the browser. Each one states the formula, the assumption, and what it refuses to do.
File-name checker
Project–originator–volume–level–type–role–number.
Beam reactions
Simply supported UDL or point load.
Concrete volume
Slab, pad or cylinder, plus allowance.
Slope and gradient
Percent, angle and 1-in-N.
Unit converter
Length, force, pressure, power, torque.
Shaft power
Torque and rotational speed to kilowatts.
Ohm's law
Two knowns, one unknown, plus power.
Voltage-drop estimate
Copper go-and-return. Not a wiring design.
Pump power
Hydraulic and shaft power from flow and head.
Pipe velocity and head loss
Darcy–Weisbach with your friction factor.
Pipe volume
Straight-pipe fill volume.
Pad bearing pressure
Average pressure only. Not Eurocode 7.
Earthworks volume
Rectangular cut or fill, plus bulking.
Three-phase power
Balanced kW and kVA. Not BS 7671.
Formwork pressure bound
Hydrostatic upper bound. Not CIRIA C766.
Rational runoff
Peak flow screen. Not a drainage design.
Direct stress
Force over area.
Young's modulus
Stress over strain.
Rectangle I and Z
Second moment and section modulus.
Beam deflection
Simply supported UDL or cantilever tip.
Reynolds number
Pipe regime screen.
Pressure from head
Static ρgh.
Steel plate weight
Rectangle at 7,850 kg/m³.
Rebar weight
Round bar, kg/m and total.
Thermal expansion
Free αLΔT.
Sensible heat
mcΔT, no phase change.
Stair rise and going
Pitch and 2R+G. Not a regulations approval.
Series and parallel resistors
Two resistors.
Power-factor correction
kVAr between two power factors.
Percentage error
Absolute difference over the true value.
Circle section
Area, I and Z of a solid circle.
Resultant force
Two perpendicular components.
Mass from density
Volume times density.
Fabric heat loss
UAΔT. Not a compliance calc.
Voltage divider
Unloaded two-resistor output.
Single-phase power
VI times power factor.
Torque from force
Force times radius.
Gear ratio
Tooth counts to output speed.
Horizontal curve
Tangent and arc of a circular curve.
Euler buckling
Pinned-pinned load. Not Eurocode 3.