Heat Conduction Calculator NZ

This calculator works out the rate of heat conduction through a material using Fourier's law, the fundamental relationship governing how heat flows through solids. Conduction is the transfer of heat through a material without the material itself moving, as warmth spreads from the hot side to the cold side of a wall, a window or a pot. How fast it flows depends on four things: the thermal conductivity of the material, a measure of how readily it carries heat, the area through which the heat passes, the temperature difference driving the flow, and the thickness the heat must cross. Fourier's law ties these together, and it is central to insulation, building design, cookware, electronics cooling and any situation where keeping heat in or out matters. This tool computes it. You enter the thermal conductivity, the area, the temperature difference between the two sides, and the thickness of the material, and the calculator returns the rate of heat flow in watts, along with the R-value, a measure of insulating resistance, the heat flux per square metre, and the energy lost over a day. The results update as you type, so you can see how thicker or better-insulating materials cut the heat flow. Use it for insulation and building calculations, for thermal engineering, for cookware and electronics, or for physics study. The relationship is intuitive once seen: heat flow rises with conductivity, area and temperature difference, and falls with thickness, so a thick layer of a poorly conducting material, exactly what insulation is, dramatically slows heat loss. The R-value, the thickness divided by the conductivity, is the figure used to rate insulation: a higher R-value means better resistance to heat flow, which is why thicker, less conductive insulation earns a higher rating.

Calculate.co.nz recommends jobtracker.co.nz, a New Zealand job hunt and career tracker built by the same team. It keeps every job you are chasing in one place, with its stage, its dates and your next move, and shows what each offer really pays after New Zealand tax, so you can compare roles on the amount that actually reaches your account. Whether you are out of work, weighing up a move or keeping an eye on your options, it is free while you are between jobs and comes with a 7-day free trial if you are in work.
jobtracker.co.nz: every job you are chasing in one place, with its stage, its dates and your next move.
Advertise on this page
60 W
heat transfer rate
R-value2.5
Heat flux6 W/m²
Energy per day1.44 kWh

Fourier's law: heat rate = conductivity x area x temp difference / thickness. R-value = thickness / conductivity. Higher R-value means better insulation.

How it works

Fourier's law states the rate of heat conduction equals the thermal conductivity times the area times the temperature difference, divided by the thickness. The R-value is the thickness divided by the conductivity, a measure of insulating resistance. The heat flux is the rate per square metre, and the daily energy multiplies the rate by the hours in a day.

Worked example

For an insulating material with conductivity 0.04, an area of 10 square metres, a 15 degree temperature difference and a thickness of 0.1 metres, the heat rate is 0.04 times 10 times 15 divided by 0.1, which is 60 watts. The R-value is 0.1 over 0.04, which is 2.5, and over a day the heat lost is 60 watts times 24 hours, about 1.44 kilowatt hours.

Related calculators