Convective Heat Transfer Rate Calculator

About this calculator

Newton's law of cooling describes how heat transfers between a solid surface and a moving fluid (air, water, or another fluid) flowing past it — the process known as convective heat transfer. The rate of heat transfer, Q, is proportional to the convective heat transfer coefficient (h), which depends on the fluid's properties and flow conditions, the surface area (A) in contact with the fluid, and the temperature difference (ΔT) between the surface and the fluid: Q = h·A·ΔT.

This calculator computes Q directly from those three inputs. It's a foundational formula in thermal and mechanical engineering, used to size heat sinks and radiators, estimate heat loss from pipes and building surfaces, and analyze cooling systems for electronics — anywhere a designer needs to know how quickly heat will move off a surface into a surrounding fluid.