A SaaS Quick Ratio measures how effectively your acquisition can fight off / outrun your churn. In non-SaaS context, Quick Ratio measures company’s ability to pay its liabilities with its near cash or quick assets.
The recommended target for this metric is to be over 4.
(New MRR + Expansion MRR) / (Contraction MRR + Churned MRR)
FirstOfficer discourages the use of SaaS Quick Ratio and offers Growth-to-New Ratio instead:
MRR Growth / (New MRR + Upgrade MRR)
It similarly measures how much of the gained MRR you get to keep.