Magnetic Flux Calculator. Magnetic flux measures how much of a magnetic field passes through a surface — a core concept in electrical engineering, motor design, and electromagnetic induction. Enter your Magnetic Field (B), Area (A), Angle (θ), and Number of Turns (N) into the Magnetic Flux Calculator to get the Magnetic Flux (Φ) in Webers. Secondary outputs include Flux Density and Total Flux accounting for all coil turns. Also try the Coulomb's Law Calculator.
Magnetic flux (Φ) is the total magnetic field passing through a surface. It's calculated using the formula Φ = B × A × cos(θ), where B is magnetic field strength in Tesla, A is the area in square meters, and θ is the angle between the field and surface normal. See also our Volt to Electron Volt Calculator.
When the magnetic field is perpendicular to the surface (θ = 0°), cos(0°) = 1, so the flux is maximum: Φ = B × A. This gives the highest possible flux value for the given field strength and area.
Magnetic flux is measured in webers (Wb). One weber equals one Tesla-meter squared (T⋅m²). The magnetic field is measured in Tesla (T) and area in square meters (m²).
The angle θ is measured between the magnetic field direction and the normal (perpendicular) to the surface. As the angle increases from 0° to 90°, the flux decreases according to cos(θ). At 90°, the flux becomes zero.
Magnetic flux density (B) is the magnetic field strength per unit area, measured in Tesla. Magnetic flux (Φ) is the total field passing through a surface, measured in webers. Flux = flux density × area × cos(angle).
For a coil with N turns, the total flux linkage is N × Φ, where Φ is the flux through one turn. This is important in electromagnetic induction calculations where each turn contributes to the total induced EMF.
Earth's magnetic field is about 25-65 μT (0.000025-0.000065 T), refrigerator magnets are around 0.001-0.01 T, MRI machines use 1.5-3 T, and superconducting magnets can reach 10+ T. Laboratory electromagnets typically range from 0.1-2 T. You might also find our Dipole Moment Calculator useful.