Effectiveness-NTU Calculator

Written by Great Medico

Updated September 26, 2026 1 min read

Type of calculation

Heat exchanger

Cold fluid mass flow

kg/s

Cold fluid specific heat

J/(kg·K)

Cold fluid heat capacity rate

W/K

Cold inlet temperature

Cold outlet temperature

Hot fluid mass flow

kg/s

Hot fluid specific heat

J/(kg·K)

Hot fluid heat capacity rate

W/K

Hot inlet temperature

Hot outlet temperature

Actual heat-transfer rate

Overall heat-transfer coefficient

W/(m²·K)

Heat-transfer area

m²

Number of transfer units (NTU)

Effectiveness (ε)

Your Result

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Ready to calculate

Enter values and click Calculate.

Effectiveness-NTU Calculator evaluates heat-exchanger effectiveness using the visible hot- and cold-side capacity inputs.

How the calculation works

Each heat-capacity rate can be entered directly or calculated as C = ṁc_p. The calculator uses C_min, C_max, C_r = C_min/C_max, and NTU = UA/C_min. Counter-flow and parallel-flow use their standard ε–NTU relationships; cross-flow uses an engineering approximation. With inlet temperatures, heat transfer is estimated as Q = εC_min(T_h,in − T_c,in).

Limitations and notes

Real exchanger performance can differ because of phase change, fouling, heat loss, maldistribution, variable properties, or a flow arrangement not represented by the selected model.

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