Metric Republic / Mechanical & HVAC engineering / Heating / Chilled Water Flow Calculator

Heating / Chilled Water Flow Calculator

Calculate water mass and volume flow from thermal duty and supply-return ΔT.

Updated September 2026

How it works

Calculate water mass and volume flow from thermal duty and supply-return ΔT.

Formula:
ṁ = Q/(cp·ΔT); V̇ = ṁ/ρ.

Before you use the result: For glycol or other fluids, use temperature- and concentration-appropriate properties.

Practical use

Use verified material data and project geometry. Treat results as planning estimates and compare them with the energy/thermal requirements that apply to the project.

Keep units consistent with the source information.
Use project-specific densities, pack sizes and coverage rates where provided.
Round purchasing quantities to supplier packaging and delivery rules.

How to use this calculator: Heating / Chilled Water Flow Calculator

Calculate water mass and volume flow from thermal duty and supply-return ΔT.

Quick workflow

Enter the project values from the latest drawing, specification or verified site measurement.
Check units, material properties, allowances and any code- or supplier-specific parameters before calculating.
Review the result together with the formula, assumptions and the related checks shown on this page.

Worked example

Example inputs: Thermal duty [kW]: 100; Supply-return ΔT [K]: 10; Specific heat cp [kJ/kgK]: 4.186; Fluid density [kg/m³]: 998.

Using the sample values built into the calculator, the calculation gives approximately: Mass flow: 2.389 kg/s; Volume flow: 8.617 m³/h.

What the result means

Calculation method: ṁ = Q/(cp·ΔT); V̇ = ṁ/ρ.

Before using the result: For glycol or other fluids, use temperature- and concentration-appropriate properties.

Common questions

What does this calculator do?

Calculate water mass and volume flow from thermal duty and supply-return ΔT.

Which inputs should I verify?

Key inputs to verify include: Thermal duty [kW], Supply-return ΔT [K], Specific heat cp [kJ/kgK], Fluid density [kg/m³].

Can I use this result for final design or ordering?

Use the result as a transparent planning or checking aid. Final design, code compliance, supplier selection and project-specific decisions still need to be verified where applicable. For glycol or other fluids, use temperature- and concentration-appropriate properties.

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