The formula
How it works
Calculate insert DNA mass for a ligation reaction from vector mass, fragment sizes and molar ratio.
FAQ
What does the ligation calculator calculate?
It calculates the main result shown at the top of the page from the values you enter, using a standard biology formula. The result is meant for planning and checking arithmetic, not as a substitute for professional judgment when safety, health or regulations matter.
What units should I use?
Use the units shown beside each input and keep related values consistent. If you use a different unit system, convert all inputs first so the formula still compares like with like.
What happens if I enter zero?
Zero is allowed where it makes mathematical sense. If a denominator would be zero, the calculator returns 0 or an explanatory result instead of dividing by zero.
Can I use decimal values?
Yes. Decimals are useful for small samples, partial hours, fractional acres, concentrations and measured values that are not whole numbers.
Why is my answer rounded?
The calculator rounds display values so they are easy to read. The calculation itself uses the full numeric value available in the browser.
How can I check the result by hand?
Copy the formula shown on the page, substitute your inputs, and work through the multiplication, division or logarithm step by step.
Does the calculator save my inputs?
The site can remember recent calculator inputs in your browser, but it does not send those values to a server for the calculation.
Is this formula always exact?
The arithmetic is exact for the model, but real-world measurements can vary because of sampling error, instrument precision, biological variation or field conditions.
What edge cases should I watch for?
Watch for negative counts, impossible dates, zero starting amounts, and ratios that imply something cannot physically happen. Those usually mean one of the inputs needs checking.
Can I compare scenarios?
Yes. Change one input at a time and watch how the result moves. That is often the fastest way to understand which variable matters most.
About the ligation calculator
This calculator estimates how many nanograms of insert DNA to add for a chosen insert-to-vector molar ratio.
How to use the calculator
Enter the vector mass, vector length, insert length and desired molar ratio. A 3:1 insert-to-vector ratio is a common starting point for many cloning ligations.
Formula
DNA mass is proportional to length at equal molecule count, so .
Applications
Ligation calculations help set up cloning reactions, compare fragment sizes and avoid using far too much or too little insert DNA.