FAQ: What is the difference between the NEBNext UltraExpress™ DNA Library Prep Kit and the NEBNext® Ultra™ II DNA Library Prep Kit? How do I choose the right one?

The NEBNext UltraExpress DNA Library Prep Kit has been optimized for streamlined library prep processing with one adaptor concentration and one PCR cycling condition used for all samples within the 10 – 200 ng input range.

NEBNext Ultra II DNA Library Prep Kit has more customized conditions based on DNA input amount, more steps and cleanups, a longer workflow time, and a broader input range recommendation (500 pg – 1 µg).

Both kits produce high yields of high-quality libraries, but we recommend choosing NEBNext UltraExpress DNA  for all of your standard samples within the stated input amount range, where speed is paramount. We recommend choosing NEBNext Ultra II DNA for more complex and precious samples (e.g., GC-rich, low quality, or low input).