Cell Viability Calculator
Calculate percent cell viability from trypan blue exclusion assay. Find live cells, dead cells, total cell count, and viability percentage from hemocytometer counts.
🦠 Cell Biology📐 Viability% = (live cells / total cells) × 100🧬 Biology
Live cells counted (trypan blue-excluding)
Dead cells counted (blue-stained)
Volume counted (mL, e.g. hemocytometer)
Dilution factor
Please enter valid values.
Formula & Reference
| Variable | Symbol | Formula | Units |
|---|---|---|---|
| Cell Viability Calculator | — | Viability% = (live cells / total cells) × 100 | % |
Step-by-Step Examples
Example 1
Healthy culture
85 live + 15 dead cells in hemocytometer grid (0.0001 mL volume). Diluted 1:2 before counting.
- Viability = 85/100 × 100 = 85%
- Cell density = 100/0.0001 × 2 = 2×10^6 cells/mL
- 85% is acceptable for most experiments
✓ 85% viable, 2×10^6 cells/mL
Example 2
Stressed culture
40 live + 60 dead. Same volume.
- Viability = 40/100 × 100 = 40%
- Poor viability: check culture conditions
- Do not use for experiments requiring >80% viability
✓ 40% viable: culture severely stressed
Example 3
After freeze-thaw
70 live + 30 dead from frozen stock.
- Viability = 70%
- Acceptable post-thaw recovery
- Allow cells to recover 24-48h before experiments
✓ 70% viable after thawing
Real-World Applications
Cell Biology Research
Viability must be >80% before experiments. Low viability biases results and wastes materials.
Drug Testing
Cell viability assay measures cytotoxicity. IC50 = drug concentration killing 50% of cells.
Bioproduction
Monitor viability in bioreactors. Declining viability signals nutrient depletion or metabolite accumulation.
Transplantation
Cell therapy products require high viability (>70-90%) before infusion. Release testing criterion.
Common Mistakes to Avoid
⚠️
Count ≥200 cells for statistical confidence
Counting fewer cells increases statistical error. 100 cells: ±10% error. 400 cells: ±5% error.
⚠️
Trypan blue must be fresh
Trypan blue solution degrades. Old solution stains live cells. Use fresh solution within 3 months of opening.
⚠️
Count multiple fields and average
Count at least 5 grid squares on hemocytometer and average. Never count edge cells (only two adjacent sides).
Frequently Asked Questions
What is trypan blue exclusion? ▾
Living cells with intact membranes exclude trypan blue dye. Dead cells with damaged membranes take up blue dye. Simple, rapid, inexpensive viability assay.
What are alternatives to trypan blue? ▾
Propidium iodide (flow cytometry, more sensitive), MTT assay (metabolic activity), Annexin V/PI (apoptosis vs necrosis), ATP-based luminescence (CellTiter-Glo).
What viability is required for experiments? ▾
Transfection: >90%. Drug treatments: >80%. Routine culture: >85%. Frozen stock thaw: >70% acceptable (allow recovery).
What causes low cell viability? ▾
Trypsinization time too long, pipetting too vigorously, incorrect temperature, pH out of range, contamination, mycoplasma, nutrient depletion, improper thawing.
Can cells look healthy but be dead? ▾
Cells can look morphologically normal but be metabolically inactive (VBNC-like state). Use multiple viability methods if in doubt: trypan + ATP assay + morphology.