The invention concerns methods of quantification of an analyte, A, in a test sample by means of a single immunochromatographic device, such as a lateral flow device (LFD). One method comprises the steps of: a) mixing a determined amount of said test sample with a determined amount of a quantification agent, QA1, said QA1 being capable of binding specifically and simultaneously both to an immobilized binding partner and to A, thus obtaining a mixture wherein the amount of A in said test sample is reflected by the ratio of the concentration of A-QA1 complex formed to the concentration of free QA1 in said mixture; b) applying a determined volume of said mixture to said device equipped with a test band in which said binding partner of the QA1 is immobilized, so that A-QA1 complex and free QA1 are immobilized at said test band in a ratio that relates to their concentration ratio in the mixture applied, said volume of mixture being determined to provide a total amount of A-QA1 complex and free QA1 capable of sufficiently saturating the immobilized binding partner in said test band; c) measuring the amount of either said A-QA1 complex or said free QA1 immobilized at the test band by means of an appropriately chosen detection procedure; d) comparing the result obtained from the test sample with the results obtained from calibration samples containing known or allocated amounts of A and thus determining the amount of A in said test sample. By including the two procedural stages a) and b) this greatly diminish or eliminate the sources of run-to-run variation.