Cell Passage Calculator

How to Use the Cell Passage Calculator

Select the tab matching your cell type. For Adherent Cells, choose your current and new vessel sizes, enter the current cell density (from a hemocytometer count), and set your target seeding density. The calculator will generate a complete step-by-step trypsinisation and reseeding protocol including volumes.

For Suspension Cells, enter current concentration, current volume, your desired target concentration, and the final new culture volume. The calculator will determine how much of your current suspension to transfer and how much fresh media to add.

Split Ratio and Seeding Density

The split ratio describes how many new flasks are seeded from one confluent flask. A 1:3 split means one flask contents divided into three new flasks. Typical split ratios range from 1:2 to 1:10 depending on cell growth rate and intended use.

Common Seeding Densities

• HeLa, HEK293, COS-7: 20,000–50,000 cells/mL for routine passage
• CHO cells: 150,000–300,000 cells/mL for suspension culture
• Primary fibroblasts: 5,000–15,000 cells/mL (slower growing)
• Jurkat, THP-1 (suspension): 200,000–400,000 cells/mL
• Always refer to your cell line's specific data sheet for recommended seeding density.

When to Passage Adherent Cells

• Passage when cells reach 80–90% confluency — never let them reach 100% (contact inhibition).
• Avoid passaging cells that are stressed, showing morphological changes, or below 85% viability.
• Use warm trypsin (37°C) and do not over-trypsinise — check detachment every 1–2 minutes.
• Neutralise trypsin with at least 3× volume of serum-containing medium immediately after detachment.