Harvest Window Predictor

Find the optimal harvest day from VCD, viability, glucose, and lactate trajectories. Integrated rules for CHO mAb, AAV/lentivirus, HEK293, Sf9, and microbial fed-batch.

Process preset
Presets set the decision thresholds below. Adjust any threshold to match your process.
Culture data ?
Tab, comma, or semicolon delimited. First row can be a header (auto-skipped). Leave cells blank (or —) if you don't track a signal.
Decision rules ?
Viability drop to
Glucose depletion below
Lactate re-accumulation above
IVCD plateau (ΔIVCD < % of peak)
Days after peak VCD
Paste your culture data and click Predict harvest day to see the recommendation.

How the harvest window is calculated

Harvest timing is a multi-signal decision. This tool evaluates up to five independent harvest-trigger rules against your data and returns the earliest day any rule fires — because the first signal to trigger typically defines the quality-limited harvest day.

Rule 1 — Viability floor. Most mAb processes harvest at 70–85% viability. Below the floor, host cell protein and DNA release accelerate; fragmentation and aggregation rise.

Rule 2 — Glucose depletion. Below ~1 g/L, cells enter starvation stress and proteases are released. Either feed or harvest immediately.

Rule 3 — Lactate re-accumulation. After the CHO lactate shift (consumption phase), rising lactate means the culture is losing TCA flux and transitioning to stress. Harvest within 24 h.

Rule 4 — IVCD plateau. Because titer ≈ qP × IVCD, when the daily IVCD increment drops below ~7% of peak daily IVCD, further culture time adds little to final titer but risks quality loss.

Rule 5 — Post-peak VCD. A backup rule: once VCD has fallen for 3 consecutive days after peak, the culture is in death phase regardless of other signals.

Related tools

Growth Curve Fitter
Extract μmax, doubling time, lag phase from OD/VCD data
Fed-Batch Calculator
Design exponential feeding profiles and predict biomass
CellTrack
Log timepoints, track VCD, viability, IVCD in real time

Frequently asked questions

When should I harvest a CHO fed-batch bioreactor?
Harvest when viability drops to 70–80%, glucose is depleted below 1 g/L, or the IVCD–titer curve has plateaued for 24–48 h — whichever comes first. The lactate shift (from accumulation to consumption) is a strong positive indicator, but once lactate re-accumulates, harvest within 24 h. Typical CHO mAb fed-batch harvest is day 12–16.
What viability should I harvest at?
Standard mAb processes harvest at 70–85% viability. AAV and lentivirus production often harvest earlier (85–95%) to minimise host cell protein and DNA release. Cell-therapy starting material typically targets ≥ 90%. The threshold trades product titer against product quality.
What is IVCD and how does it relate to harvest timing?
IVCD (integral viable cell density) is the time-integral of VCD, with units of cell-days/mL or cell-hours/mL. Because specific productivity qP is roughly constant over the run, final titer ≈ qP × IVCD. Harvest decisions often target an IVCD setpoint or wait until daily IVCD increment drops below 5–10% of peak.
Why is the lactate shift important for harvest timing?
The lactate shift is when CHO cells switch from producing lactate (glycolysis-dominant) to consuming it (TCA-dominant). It signals the size-increase phase and usually precedes peak titer by 1–3 days. Cultures that re-accumulate lactate after the shift are entering stress — harvest within 24 h is recommended.