Why convert ng/µL to nM first?

Clustering and loading depend on the number of molecules, i.e. molarity. Converting mass to molarity needs the fragment length, which is why it is asked for.

What if my target is higher than my stock?

You cannot concentrate by dilution. The tool flags this — you would need to concentrate the sample instead.

Library dilution calculator

Work out how much stock and diluent to mix to reach a target loading concentration in a target final volume. Stock can be in ng/µL or nM.

How it works

Formula

C1 · V1 = C2 · V2. Stock volume V1 = (target conc × final volume) ÷ stock conc; diluent = final volume − V1. ng/µL stock is first converted to nM with the fragment length.

Worked example

A 20 nM stock to 4 nM in 50 µL: V1 = (4 × 50) ÷ 20 = 10 µL of stock, topped up with 40 µL of diluent.

When to use it

When normalising a quantified library to the picomolar/nanomolar loading concentration your sequencer expects, or diluting any nucleic-acid stock to a working concentration.

Sensible defaults

Defaults dilute a 20 nM stock to 4 nM in 50 µL. Switch the unit to ng/µL and set the fragment length to dilute a mass-quantified stock.

FAQ

Why convert ng/µL to nM first?: Clustering and loading depend on the number of molecules, i.e. molarity. Converting mass to molarity needs the fragment length, which is why it is asked for.
What if my target is higher than my stock?: You cannot concentrate by dilution. The tool flags this — you would need to concentrate the sample instead.