Pressure Drop Calculators
Analyze how pressure changes along pipelines for liquids, gases, or air flow. These calculators apply Darcy–Weisbach and Colebrook–White formulas, letting you compute pressure loss, flow velocity, and pipe diameter for any circular or rectangular duct. Useful for HVAC, gas transmission, and hydraulic design.
Calculator's features:
- Calculate pressure drop for known flow rate
- Calculate flow rate for known pressure drop
- Darcy formula for friction coefficient calculation
- Colebrook-White formula for turbulent flow calculation
- Flow in valves and fittings
- Laminar and turbulent flow
- Flow velocity/diameter calculation
Pressure Drop
For incompressible fluids
- Liquids and low-pressure gases
- Circular or rectangular pipes
- Incompressible flow (ρ = const)
- Colebrook-White equation
Gas Pressure Drop Calculator
For any perfect gas flow
- Applicable for any perfect gas in a long and closed round pipe
- Compressible ρ ≠ const.
- Isothermal T=const.
Compressible air flow
Flow rate of air flow calculations
- Flow of air in a closed round pipe
- Compressible flow ρ ≠ const.
- Isothermal flow T=const.
High pressure natural gas
Flow rate calculations of natural gas
- Applicable for natural gas lines over 1 bar, longer than 1 m
- Calculations available based on the Van der Waals method and
- Redlich-Kwong method
Calculators for Pressure Differential Flow Devices
Measure and calculate flow rate from a pressure difference across orifices, Venturi tubes, or nozzles. This group covers differential pressure flow meters including Venturi effect, orifice plates, nozzles, and Pitot tubes — essential for accurate liquid and gas flow measurement according to ISO 5167 standards.
Calculator's features:
- Calculate flow rate in pipe based on the created pressure drop,
- For liquids and perfect gases,
- Flow velocity calculation,
- Convert between volume and mass flow rate,
- Reynolds number calculation,
- Discharge coefficient calculation.
Venturi tube
Venturi effect calculation
- Quickly calculate the actual flow rate through the Venturi tube
- Flow rate calculation from the measured pressure difference caused by the flow contraction
Orifice plate calculator
Calculate orifice diameters
- Quickly calculate the actual flow rate through the orifice
- Flow rate calculation from the measured pressure drop caused by the orifice plate inserted in the pipeline
Nozzle and Venturi nozzle
Nozzle calculation
- Calculate flow rate using the static pressure difference between inlet pressure and pressure in the nozzle throat
- The calculation is according to ISO 5167-3
Prandtl probe - Pitot tube
Calculate flow velocity
- Calculate flow velocity by measuring a difference between stagnation pressure and static pressure in a single point of a flow streamline
- Applicable for airflow in rectangular and round ducts
Quick Engineering Calculators
Access fast and simple tools for everyday fluid mechanics and thermal calculations. Estimate pipe size, flow velocity, heat power, valve sizing, gas leakage, or pump performance in seconds. Ideal for quick checks and preliminary engineering design.
Pipe diameter calculator
Calculate flow velocity
- Quick pipe diameter calculation in closed, round, rectangular pipes and ducts
- Enter flow rate and velocity in text fields in the calculator and click calculate button to get results
Resistance coefficient K
Flow in valves and fittings
- Resistance coefficient (or resistance factor) K calculation for flow through valves and fittings
- Should be used with pressure drop calculator or with gas compressible flow calculator
Reynolds number
Laminar or turbulent flow
- Analyze what makes fluid flow regime laminar and what is needed to force the fluid to flow in the turbulent regime
- Calculator for all fluids and flow rates without any restriction
Thermal energy
Calculate heat energy, thermal power and flow rate
- Calculator for heat power calculation, and the flow rate calculation
- Suitable for hot water boilers, water and air heat exchangers, chillers, heaters, and other equipment
Gas offtake
Calculate offtake of gas
- Calculation of gas outflow from the pipe or through the valve to the atmosphere or to a reservoir
- Calculate the maximum flow rate when you know pressure difference and pipe diameter
LPG flow
Calculate heat power and flow rate of LPG
- Calculate flow rate, pipe diameter and heat power of liquefied petroleum gas – LPG
- Determine flow rate of an LPG in a gas furnace, for burner heat power
Control valve sizing calculator
Calculate flow coefficient
- Calculate maximum flow rate through valve for pressure drop and flow coefficient Cv
- Compare control valves from different manufacturers
Gas control valve sizing calculator
Calculate flow coefficient
- Calculate valve capacity for given upstream and downstream pressure and known Cg or Kg
- The calculator is in line with the standard EN334
Pump performance calculator
Calculate pipe flow rate and head
- Calculate the actual flow and required head of the pump (or ventilator)
- Calculate variable pump speed for known flow rate and head
Pipe wall thickness calculator
Calculation of pipe wall size
- Calculate the thickness of the pipe wall based on the known value of the internal pressure and the permitted specified minimum yield stress in the pipe
- Based on the ASME B31.8 standard
- Calculation of actual stress in the pipe
- Checking the thickness of the pipe wall for the known value of the permissible stress
- Carbon steel, stainless steel, copper and PVC pipes.