A method for determining the respiratory rate R of at least one user comprising at least the following steps implemented by at least one data processing unit comprising: a. Acquisition of at least one photoplethysmogram S(t) of said user, the step of acquiring said photoplethysmogram S(t) comprising at least one of the following steps: ∘ Measurement, preferably at a frequency which is greater than or equal to 50Hz, of said at least one photoplethysmogram S(t) by a measuring device, preferably worn or intended to be worn by said at least one user, the device comprising at least one sensor capable of measuring at least one photoplethysmogram S(t); ∘ Reception of said at least one photoplethysmogram S(t) from at least one database; b. Estimate of the heart rate Fc from said at least one photoplethysmogram S(t) acquired from said at least one user; c. Obtaining of at least three signals (S1,...S7) which are distinct from each other, each obtained signal (S1,...S7) being a function of said at least one acquired photoplethysmogram S(t); d. Generation of a signal S8 from said at least three obtained signals (S1,..., S7); e. Algorithmic processing of each of the at least three obtained signals (S1,..., S7) and of the signal S8 by at least two algorithms Ai and Aj, so as to obtain at least two estimated respiratory rates, respectively Rx.Ai and Rx.Aj, for each signal Sx processed respectively by the algorithm Ai and by the algorithm Aj, each signal Sx being taken from said at least three obtained signals (S1,..., S7) and the signal S8; the at least two algorithms Ai and Aj being distinct from each other; f. Calculation of at least two intermediate respiratory rates rm and rn from the estimated respiratory rates (Rx.Ai, Rx.Aj); g. Determination of the respiratory rate R by calculating the median of said at least two intermediate respiratory rates rm and rn. a. Acquisition of at least one photoplethysmogram S(t) of said user, the step of acquiring said photoplethysmogram S(t) comprising at least one of the following steps: ∘ Measurement, preferably at a frequency which is greater than or equal to 50Hz, of said at least one photoplethysmogram S(t) by a measuring device, preferably worn or intended to be worn by said at least one user, the device comprising at least one sensor capable of measuring at least one photoplethysmogram S(t); ∘ Reception of said at least one photoplethysmogram S(t) from at least one database; ∘ Measurement, preferably at a frequency which is greater than or equal to 50Hz, of said at least one photoplethysmogram S(t) by a measuring device, preferably worn or intended to be worn by said at least one user, the device comprising at least one sensor capable of measuring at least one photoplethysmogram S(t); ∘ Reception of said at least one photoplethysmogram S(t) from at least one database; b. Estimate of the heart rate Fc from said at least one photoplethysmogram S(t) acquired from said at least one user; c. Obtaining of at least three signals (S1,...S7) which are distinct from each other, each obtained signal (S1,...S7) being a function of said at least one acquired photoplethysmogram S(t); d. Generation of a signal S8 from said at least three obtained signals (S1,..., S7); e. Algorithmic processing of each of the at least three obtained signals (S1,..., S7) and of the signal S8 by at least two algorithms Ai and Aj, so as to obtain at least two estimated respiratory rates, respectively Rx.Ai and Rx.Aj, for each signal Sx processed respectively by the algorithm Ai and by the algorithm Aj, each signal Sx being taken from said at least three obtained signals (S1,..., S7) and the signal S8; the at least two algorithms Ai and Aj being distinct from each other; f. Calculation of at least two intermediate respiratory rates rm and rn from the estimated respiratory rates (Rx.Ai, Rx.Aj); g. Determination of the respiratory rate R by calculating the median of said at least two intermediate respiratory rates rm and rn.