Weighing method for weighing containers of pharmaceutical, medical, food substances or similar, said containers being subject to the action of an air flow, the method comprising: a) making available a weighing unit provided with two or more weighing devices; a1) placing said weighing unit within a covering and protecting structure to contain and protect said weighing unit; a2) generating a laminar air flow in said covering and protecting structure; b) weighing containers filled with a desired quantity of substance, occupying respective weighing devices of said weighing unit, obtaining an actual weight value of said filled containers; c) weighing one or more reference sample containers, having a known weight, shape and size, occupying respective remaining further one or more weighing devices of the weighing unit, thereby obtaining an actual weight value of said reference sample containers; d) calculating a weighing error of the reference sample container or containers by comparing the actual weight value of said reference sample containers with a nominal weight value of said reference sample containers; e) estimating a measurement error of the weight of the containers filled with a desired quantity of substance, assuming said measurement error of the weight of the filled containers to be equal to the weighing error calculated for the reference sample containers; f) correcting a weighing value detected for the filled containers on the base of the measurement error of the weight of the containers estimated using the reference sample containers, wherein the filled containers and said one or more reference containers are subjected to the action of the generated laminar air flow in said covering and protecting structure and have the same nominal shape and the same nominal size. a) making available a weighing unit provided with two or more weighing devices; a1) placing said weighing unit within a covering and protecting structure to contain and protect said weighing unit; a2) generating a laminar air flow in said covering and protecting structure; a1) placing said weighing unit within a covering and protecting structure to contain and protect said weighing unit; a2) generating a laminar air flow in said covering and protecting structure; b) weighing containers filled with a desired quantity of substance, occupying respective weighing devices of said weighing unit, obtaining an actual weight value of said filled containers; c) weighing one or more reference sample containers, having a known weight, shape and size, occupying respective remaining further one or more weighing devices of the weighing unit, thereby obtaining an actual weight value of said reference sample containers; d) calculating a weighing error of the reference sample container or containers by comparing the actual weight value of said reference sample containers with a nominal weight value of said reference sample containers; e) estimating a measurement error of the weight of the containers filled with a desired quantity of substance, assuming said measurement error of the weight of the filled containers to be equal to the weighing error calculated for the reference sample containers; f) correcting a weighing value detected for the filled containers on the base of the measurement error of the weight of the containers estimated using the reference sample containers,