Scientific contributor: Dr. Tayner Rodriguez Garzon · Published by Cell Culture Tools · How content is prepared
Plan how much of a harvested culture to transfer, using a target density or a chosen split ratio. Source counts refer to all wells or vessels combined into the measured harvest.
Worked examples use illustrative inputs, independent of your current calculation and selected cell line. Replace them with measured values and your lab protocol.
How to use this tool
- Choose the source format and the number of harvested wells or vessels. For a measured harvest, enter its concentration, viability and total resuspended volume after pooling.
- For an adherent culture, you can instead estimate the harvest from confluence. Supply a viable cells/cm² calibration measured for your line and conditions; the app supplies no universal calibration.
- Choose the destination format, number of destinations and final volume. Plan by a target density or by a split factor: entering 4 means 1:4 relative to one average source unit.
- Review cells per destination, the fraction of the entire pooled harvest, maximum destinations, and the suspension left over. A source split ratio and a pooled-harvest fraction describe different quantities.
- Optionally enable the growth estimate and enter a doubling time, lag and endpoint. The plotted curve and five-passage schedule use those assumptions repeatedly; they do not measure when your culture will be ready.
1 mL = 1,000 µL; 1 L = 1,000 mL. Convert volumes to mL when combining them with cells/mL or mg/mL.
Worked examples
Two pooled sources, a 1:4 split and six destinations
Inputs. Two T-75 sources pooled in 8 mL; 1,000,000 viable cells/mL (enter 100% viability); split 1:4; six T-75 destinations at 10 mL each.
- Harvest: 8 × 1,000,000 = 8,000,000 viable cells; average per source: 4,000,000.
- Each destination: 8,000,000 / 2 / 4 = 1,000,000 cells.
- Each destination takes 1 mL of stock, which is 12.5% (one-eighth) of the pooled harvest.
- Six destinations use 6 mL stock + 54 mL medium; 2 mL stock remains.
Result. Maximum eight destinations; the requested six each receive 1 mL stock + 9 mL medium.
An illustrative growth forecast
Inputs. Continue the example with 1,000,000 viable cells in 10 mL. Choose a 400,000 cells/mL endpoint, a 24-hour doubling time and a 6-hour lag.
- Target count: 400,000 × 10 = 4,000,000 cells.
- Required doublings: log₂(4,000,000 / 1,000,000) = 2.
- Time: 6 + 24 × 2 = 54 hours.
Result. Estimated first endpoint: 54 hours. Repeated model endpoints: 54, 108, 162, 216 and 270 hours.
Assumptions and interpretation
- Pooling uses an average yield per source. The app cannot reconstruct different source yields from one pooled concentration.
- Confluence is converted linearly to a cell count using your calibration. The estimate is not a substitute for a recovered viable-cell measurement when precision matters.
- Transfer arithmetic assumes a uniform suspension and does not add a dead-volume allowance or predict cell losses.
- The forecast assumes constant exponential growth after a fixed lag. It does not model crowding, nutrient depletion, cell death or changes between passages. A split ratio alone is not a growth-rate measurement.
References and source scope
These sources support the stated background and product references. Formulas explain this tool’s arithmetic; worked examples are not vendor recommendations or evidence of vendor endorsement.