Method for measuring the intensity of a current in an electrical conductor based on measurements of values of components (b l) of a magnetic field received from a set of detectors positioned relative to the electrical conductor, the position of each detector being known relative to a reference point (Pr) so that the distances (r i) between the latter and the measuring points (Pm i) made up of the detectors are determined, the method comprising the steps of: - obtaining a calculation matrix M comprising a set of terms divided into a finite number of lines and a finite number of columns, said calculation matrix M being obtained as a function of the coordinates of measuring points (Pm i) with respect to the reference point (Pr), the positioning of the set of detectors relative to the electrical conductor being such that, with a first distance defined between the reference point (Pr) and the point of the conductor closest to the reference point (Pr), the maximum of the distances (r i) of the measuring points (Pm i) relative to the reference point (Pr) is strictly less than the first distance, and the measuring points (Pm i) being arranged along a circle with the reference point (Pr) as its centre or a sphere with the reference point (Pr) as its centre, each term of a same row of the calculation matrix being proportional to the same distance (r i) between a measurement point (Pm i) and the reference point (Pr), raised to a power greater than or equal to zero, each column of the calculation matrix being raised to a power different from the other columns, - forming a measurement vector B including the measurements of component values (b l) received from said set of detectors, each component (b l) being taken according to a direction (Dmr, Dmθ, Dθ, Dφ, Dr) at a measuring point (Pm i), each measuring point (Pm i) associated with a direction (Dmr, Dmθ, Dθ, Dq>, Dr) being distinct from the other measuring points (Pm i) associated with the same direction (Dmr, Dmθ, Dθ, Dq>, Dr), - calculating components (α) of a vector of coefficients A, the vector A comprising as many components (α) as the matrix M comprises columns and satisfying the matrix relationship B = M x A, x denoting the matrix multiplication operation, so that each calculated component (α) corresponds to a coefficient of a breakdown of the magnetic field into spatial harmonics and is proportional to the intensity of the current in the electrical conductor, and - determining the intensity of the current in the electric conductor from at least the calculated components (α). - obtaining a calculation matrix M comprising a set of terms divided into a finite number of lines and a finite number of columns, said calculation matrix M being obtained as a function of the coordinates of measuring points (Pm i) with respect to the reference point (Pr), the positioning of the set of detectors relative to the electrical conductor being such that, with a first distance defined between the reference point (Pr) and the point of the conductor closest to the reference point (Pr), the maximum of the distances (r i) of the measuring points (Pm i) relative to the reference point (Pr) is strictly less than the first distance, and the measuring points (Pm i) being arranged along a circle with the reference point (Pr) as its centre or a sphere with the reference point (Pr) as its centre, each term of a same row of the calculation matrix being proportional to the same distance (r i) between a measurement point (Pm i) and the reference point (Pr), raised to a power greater than or equal to zero, each column of the calculation matrix being raised to a power different from the other columns, - forming a measurement vector B including the measurements of component values (b l) received from said set of detectors, each component (b l) being taken according to a direction (Dmr, Dmθ, Dθ, Dφ, Dr) at a measuring point (Pm i), each measuring point (Pm i) associated with a direction (Dmr, Dmθ, Dθ, Dq>, Dr) being distinct from the other measuring points (Pm i) associated with the same direction (Dmr, Dmθ, Dθ, Dq>, Dr), - calculating components (α) of a vector of coefficients A, the vector A comprising as many components (α) as the matrix M comprises columns and satisfying the matrix relationship B = M x A, x denoting the matrix multiplication operation, so that each calculated component (α) corresponds to a coefficient of a breakdown of the magnetic field into spatial harmonics and is proportional to the intensity of the current in the electrical conductor, and - determining the intensity of the current in the electric conductor from at least the calculated components (α). - forming a measurement vector B including the measurements of component values (b l) received from said set of detectors, each component (b l) being taken according to a direction (Dmr, Dmθ, Dθ, Dφ, Dr) at a measuring point (Pm i), each measuring point (Pm i) associated with a direction (Dmr, Dmθ, Dθ, Dq>, Dr) being distinct from the other measuring points (Pm i) associated with the same direction (Dmr, Dmθ, Dθ, Dq>, Dr), - calculating components (α) of a vector of coefficients A, the vector A comprising as many components (α) as the matrix M comprises columns and satisfying the matrix relationship B = M x A, x denoting the matrix multiplication operation, so that each calculated component (α) corresponds to a coefficient of a breakdown of the magnetic field into spatial harmonics and is proportional to the intensity of the current in the electrical conductor, and - determining the intensity of the current in the electric conductor from at least the calculated components (α).