Resistivity Calculator

Resistivity is the property that decides how good a material is at carrying electric current, and this calculator uses it to find the resistance of a length of wire, or to work back to the resistivity itself from a measured resistance. Choose whether to solve for resistance or resistivity, pick a material to load a standard resistivity value or type your own, enter the length and the cross-sectional area, and the answer appears as you type. The relationship at its heart is one of the most useful in electricity: resistance equals resistivity times length divided by cross-sectional area. It captures three intuitive truths at once. A material with a high resistivity, like nichrome, resists current strongly and is perfect for heating elements, while one with a low resistivity, like copper or silver, conducts beautifully and is used for wiring. A longer wire has more resistance, because the current has further to push through. And a thicker wire has less resistance, because there is more room for the current to flow, which is exactly why heavy-duty cables use thick conductors to avoid losses and overheating. Separating resistivity from resistance is an important idea in itself: resistivity belongs to the material no matter its shape, whereas resistance depends on the particular piece in front of you. The calculator includes built-in resistivity values for common conductors so you do not have to look them up. That makes it genuinely useful for physics and electronics students learning about conductors and Ohm's law and checking homework, and for electricians, engineers and hobbyists sizing cables, estimating wire resistance and choosing materials. Using ohm metres, metres and square millimetres gives a resistance in ohms. The formula and a worked example are explained clearly below.

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Area is entered in square millimetres and converted to square metres. Resistivity uses ohm metres.