Process engineering calculations
Free online calculators, browser tools and Excel workbooks for the calculations plant, process and utilities engineers do every week — each one checked against a published worked example.
PlantCalcKit is a set of engineering calculators built around real plant work: checking a pump against its curve, finding out how badly an exchanger is fouled, sizing a line or an orifice plate, getting the density and viscosity of a process stream, or working out what a cooling tower is really doing. Every calculator shows its method and its limits, works in SI, US and British units, and has been checked against a published worked example before release (see how we check our tools).
Three ways to calculate
- Free online calculators — quick answers in your browser, no sign-up: 48 free calculators.
- Online tools — the full Excel tools running in your browser. Enter and check your data free; unlock the results for USD 9 (3 runs) or USD 15 a month: all online tools.
- Excel tools — the same calculations as protected, documented workbooks you keep, with a printable report for the calculation file: the shop.
Calculation guides by subject
Pump calculations
Total head, hydraulic and shaft power, efficiency, NPSH available and margin, system curve and operating point, affinity laws, metering pumps.
Heat exchanger calculations
Heat duty, LMTD and the F factor, U and area, fouling resistance, condensers and reboilers, plate exchangers, waste heat recovery.
Pipe pressure drop and orifice sizing
Darcy–Weisbach pressure drop, line sizing, fittings, gas choking, ISO 5167 orifice plates, control valve Cv and gas flow compensation.
Fluid properties
Density, viscosity, heat capacity, thermal conductivity, vapour pressure and compressibility of liquids, gases and mixtures from a 543-chemical library.
Cooling tower calculations
Evaporation, blowdown and makeup, cycles of concentration, LSI and RSI, performance testing and Merkel thermal rating.
Energy and utilities
Boiler efficiency, combustion excess air, insulation heat loss, compressed air leaks, compressor power and utilities cost.
What makes an engineering calculator worth trusting
A calculator is only as good as its method and its checks. Every PlantCalcKit tool states the equations it uses and where they come from — for example Darcy–Weisbach with the Colebrook equation for pipe friction, ISO 5167-2 (Reader-Harris/Gallagher) for orifice plates, IEC 60534 for control valve sizing, and the Merkel method for cooling towers. Inputs are checked against hard limits and typical ranges, and the status line tells you when a value looks wrong before you rely on the answer.
Questions
Are the calculators free?
The 48 calculators under Free calculators are free with no sign-up. The online tools let you enter and check your data free; the full results are unlocked with a 3-run pack (USD 9) or a subscription (USD 15 a month or USD 99 a year).
Which units can I use?
SI, US customary and British units, mixed freely; the tools convert internally.
Are the online tools the same as the Excel tools?
Yes. The online tool runs the workbook's own formulas, checked cell by cell against the Excel file.
Can I use the results for design?
The tools give engineering estimates for screening, troubleshooting and training. Check important decisions against site data, the equipment maker and your plant's approved procedures.
More calculation guides
- Pump calculations
- Heat exchanger calculations
- Pipe pressure drop and orifice sizing
- Fluid properties for process calculations
- Cooling tower calculations
These guides and calculators give engineering estimates for screening, troubleshooting and training. Check important decisions against site data, your equipment maker and your plant's approved procedures.