What is a weber in simple terms?

A weber is the SI unit of magnetic flux, which is the total amount of magnetic field passing through a given area. One weber equals one volt-second, meaning that if the flux linking a single-turn coil changes by one weber in one second, it induces one volt across that coil.

What is the difference between a weber and a tesla?

A weber measures total magnetic flux through an area, while a tesla measures magnetic flux density, the flux per unit area. They are related by 1 tesla = 1 weber per square metre, so one weber spread evenly over one square metre gives a flux density of one tesla.

How many maxwells are in a weber?

One weber equals 100 million maxwells (1 Wb = 10^8 Mx). The maxwell is the older CGS unit of magnetic flux, so the weber is the far larger SI replacement used in modern engineering and physics.

What is the formula for a weber?

One weber equals one volt multiplied by one second (1 Wb = 1 V s), which is also equal to one tesla multiplied by one square metre (1 Wb = 1 T m squared). It expresses magnetic field strength integrated over the area it passes through.

Who is the weber named after?

The weber is named after Wilhelm Eduard Weber (1804 to 1891), a German physicist who made major contributions to electromagnetism and, with Carl Friedrich Gauss, built one of the first electromagnetic telegraphs.

What Is a Weber? Magnetic Flux Explained

Definition

A weber (symbol: Wb) is the SI unit of magnetic flux — the total amount of magnetic field passing through a given surface. Where magnetic field strength describes how concentrated a field is at a point, flux describes how much of that field threads through an entire area.

The weber is defined as one volt-second, which is also equal to one tesla multiplied by one square metre:

1 Wb = 1 V·s = 1 T·m²

Expressed in SI base units, the weber is kilogram metre squared per ampere second squared:

1 Wb = 1 kg·m²·A−¹·s−²

You can picture magnetic flux as the number of field lines crossing a loop. Hold a wire loop in a magnetic field and the flux through it depends on three things: the strength of the field, the area of the loop, and the angle between the field and the loop. Tilt the loop edge-on to the field and the flux falls to zero, even though the field itself has not changed.

Weber, Tesla & Faraday's Law

The weber and the tesla describe the same magnetism from two angles. The tesla is flux density — flux spread across area — so the two units are linked by a simple relationship:

Φ = B × A, or equivalently 1 Wb = 1 T × 1 m²

Here Φ is the flux in webers, B is the flux density in teslas, and A is the area in square metres. A field of 0.5 T passing straight through a coil of area 0.2 m² produces a flux of 0.5 × 0.2 = 0.1 Wb.

The weber matters most because of Faraday's law of induction, the principle behind every electric generator, transformer, and induction motor. A changing magnetic flux induces a voltage:

EMF = −dΦ/dt

In words, the voltage induced in a loop equals the rate at which the flux through it changes. Because flux is measured in webers and time in seconds, the induced electromotive force comes out in volts — which is exactly why one weber equals one volt-second. The minus sign reflects Lenz's law: the induced voltage opposes the change that produced it.

Everyday Examples

Magnetic flux values span an enormous range, from the faint signal picked up by a sensor to the powerful fields inside heavy electrical machinery. The table below lists familiar reference points.

Situation	Approximate Flux
Earth's field through a small 1 cm² coil	~5 × 10⁻⁹ Wb (5 nWb)
Signal in a sensitive pickup or sensor coil	~10⁻⁷ Wb (0.1 µWb)
Fridge magnet through a coin-sized loop	~10⁻⁵ Wb (10 µWb)
Small transformer or relay core	~10⁻⁴ Wb (0.1 mWb)
Mains power transformer core	~0.001–0.01 Wb
Large industrial motor or generator core	~0.01–0.1 Wb

Related Units

Because flux ranges across many orders of magnitude, SI prefixes and the older CGS unit are both still seen. The maxwell is the legacy CGS unit, where one weber equals 100 million maxwells.

Name	Symbol	Value in Webers	Notes
Microweber	µWb	0.000001 Wb (10⁻⁶ Wb)	Small coils and sensors
Milliweber	mWb	0.001 Wb (10⁻³ Wb)	Transformer and motor cores
Weber	Wb	1 Wb	SI base unit of magnetic flux
Maxwell	Mx	10⁻⁸ Wb	CGS unit; 1 Wb = 10⁸ Mx

History

The weber is named after Wilhelm Eduard Weber (1804–1891), a German physicist who made fundamental contributions to the study of electricity and magnetism. Working closely with the mathematician Carl Friedrich Gauss at the University of Göttingen, Weber helped develop a consistent system of electrical units and, in 1833, the pair built one of the first practical electromagnetic telegraphs, sending signals across the town between their laboratories.

The unit was adopted to honour Weber and was formally defined as part of the International System of Units (SI), replacing the older CGS maxwell for most scientific and engineering work. Today the weber underpins the design of every transformer, generator, and motor, since each relies on Faraday's law to convert changing magnetic flux into useful voltage.

Need to switch between webers, milliwebers, and maxwells? Use our magnetic flux converter for fast, precise results.