The calculations people actually rerun
These are the everyday relationships: stress, deflection, flow, power, weight, stairs. Each page keeps the formula visible. None of them is a code check.
| Calculation | On this site | It will not do |
|---|---|---|
| Ohm's law and resistors | Ohm, series and parallel | Cable sizing |
| Voltage drop | Copper estimate | BS 7671 |
| Three-phase power and power factor | Power, kVAr | Harmonic study |
| Concrete volume | Volume | Mix design |
| Beam moment and deflection | Reactions, Deflection | Section check |
| Direct stress and modulus | Stress, E | Buckling |
| Rectangle I and Z | Section | Steel tables |
| Slope and stairs | Slope, Stairs | Approved Document approval |
| Pipe velocity, Reynolds, head | Flow, Reynolds, Head | Network design |
| Pump and shaft power | Pump, Shaft | Machine selection |
| Steel and rebar weight | Plate, Rebar | A bar schedule |
| Thermal expansion and sensible heat | Expansion, Heat | Restrained stress, phase change |
| Earthworks and runoff | Volume, Runoff | Mass haul, FEH |
| Percentage error | Error | An uncertainty budget |
| Circle section, resultant, mass | Circle, Resultant, Mass | Hollow sections, moisture |
| Heat loss, divider, single-phase power | Heat loss, Divider, Single phase | Compliance calc, loaded divider, cable size |
| Torque, gears, curve, Euler | Torque, Gears, Curve, Euler | Eurocode buckling, transition curves |
Why these sit together
The common set is the arithmetic that turns up beside almost every model: a stress, a section, a deflection, a unit change, a percentage gap. They are here so a federation review can check the order of a number without opening a design workbook.
Each page states the formula and one worked case. The worked case is the regression check. A 100 kN force on 2,000 mm² is 50 N/mm². A 100 mm circle is 7,854 mm². If the page disagrees with that, the page has changed and the method note is wrong.
Do not stack them into a utilisation. Stress, modulus and deflection answer different questions. The stop is written on each page.
Last checked 3 October 2026. Official design methods stay in the named standard. See standards these tools do not replace.