In this report, we demonstrate the assembly of length-programmed DNA nanostructures using a single 16 base sequence and its complement as building blocks. To achieve this, we applied the Vernier mechanism to DNA assembly, which uses a mismatch in length between two monomers to dictate the final length of the product. Specifically, this approach relies on the interaction of two DNA strands containing a different number (n, m) of complementary binding sites: these two strands will keep binding to each other until they come into register, thus generating a larger assembly whose length (n × m) is encoded by the number of binding sites in each strand. While the Vernier mechanism has been applied to other areas of supramolecular chemistry, here we present an application of its principles to DNA nanostructures. Using a single 16 base repeat and its complement, and varying the number of repeats on a given DNA strand, we show the consistent construction of duplexes up to 228 base pairs (bp) in length. Employing specific annealing protocols, strand capping, and intercalator chaperones allows us to further grow the duplex to 392 base pairs. We demonstrate that the Vernier method is not only strand-efficient, but also produces a cleaner, higher-yielding product than conventional designs.