🔗 Ligation Calculator
Calculate how much insert DNA you need for a cloning ligation reaction given your vector amount and desired molar ratio.
What This Calculator Does
This calculator determines how many nanograms of insert DNA to add to a ligation reaction, given the amount of vector you’re using and the desired molar ratio of insert to vector.
The Formula
It uses the standard molecular cloning equation: Insert mass (ng) = Molar ratio × Vector mass (ng) × (Insert length / Vector length). This accounts for the fact that DNA molecules of different lengths have different molar masses, so simply matching mass-for-mass would not give equal (or a desired ratio of) molecule counts.
- A molar ratio of 3:1 (insert:vector) is a common starting point for standard ligations.
- Vector and insert lengths should be entered in base pairs (bp).
This is a general lab planning tool for educational purposes; actual ligation efficiency depends on many additional factors such as DNA quality, ligase activity, and reaction conditions.