# Passage Dilution Ratio Calculator (1:N) 1:N split from current and target densities, with keep/fresh-medium volumes and inter-passage doublings. Educational use only. > Canonical page: https://elysiatools.com/en/tools/passage-dilution-ratio - **Category:** Education - **Keywords:** passage dilution ratio, split ratio calculator, 1 to n split cell culture, subculture ratio, seed density from current density, keep volume fresh medium, cell passage calculator, split cells 1 10, cell culture calculator, lab calculator ## Overview The Passage Dilution Ratio Calculator (1:N) calculates a cell culture split ratio from current and target viable-cell densities. In volume mode, it also calculates the culture volume to keep and the fresh medium to add, with optional passage doublings and equivalent doubling time. Educational use only. ## Inputs - **Calculation Mode** (select): Just the 1:N ratio, or the split volumes for a specific culture volume. - **Current Density (cells/mL)** (number): Viable-cell density of the culture being passaged (from a hemocytometer count). - **Target Density (cells/mL)** (number): Seed density you want in the new flask. - **Culture Volume (mL)** (number): Total volume of the culture being split (volume mode). - **Interval to Next Passage (h)** (number): Optional planned hours between passages, for doublings and doubling time. - **Decimal Places** (number) ## When to use - Determine the 1:N passage ratio needed to reach a target cell density. - Calculate how much of an existing culture to keep and how much fresh medium to add. - Estimate doublings between passages when the interval to the next passage is known. ## How it works - Enter the current viable-cell density and the desired target density in cells/mL. - Choose Ratio only to calculate the split ratio, or Split a specific volume to include volume calculations. - In volume mode, enter the total culture volume to calculate the volume to keep and fresh medium to add. - Optionally enter the passage interval and decimal places to estimate doublings and equivalent doubling time. ## Use cases - Plan routine adherent-cell subcultures by converting measured density into a practical 1:2 to 1:5 split. - Prepare fast-growing suspension-cell passages with larger dilution ratios such as 1:10. - Calculate keep and fresh-medium volumes for a defined flask or culture volume. ## Frequently asked questions ### What does a 1:N passage ratio mean? It means one part of the existing culture is reseeded into a total of N parts at the target density. ### How is the split ratio calculated? The calculator divides the current density by the target density: N = current density ÷ target density. ### What does volume mode calculate? It calculates the volume to keep from the existing culture and the fresh medium needed to maintain the entered total volume. ### What are doublings between passages? They estimate the number of cell doublings represented by the split ratio using n = ln(N) ÷ ln(2). ### Is this calculator suitable for clinical decisions? 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