Methods are presented, in accordance for the present invention, for determining the length of a target probe. The methods have the steps of designing a first hybridization probe having a nucleic acid sequence, a portion of which overlaps with the nucleic acid sequence of a second hybridization probe, designing a second hybridization probe having a nucleic acid sequence, a portion of which overlaps with the nucleic acid sequence of the first hybridization probe, designing a target probe having the nucleic acid sequences of both the first and second hybridization probe and affixing the target probe to a solid support, labeling one of the first and second hybridization probes, but not both, and contacting simultaneously the first and second probes to the target probe, and detecting and quantifying the signal intensity ration between the labeled and non-labeled probes, whereby said ration indicating whether the target probe synthesis has reached full length.