Free AI-Assisted

Cell Passage Calculator

Plan cell passaging from confluency or density—split ratios, volumes, growth timelines, and bench recipes—no account. Built-in AI agent assistant support.

Open tool workspace

Need help with bioinfo analysis? See our bioinformatics services.

Key facts

Key facts about Cell Passage Calculator
FactValue
Culture modesAdherent (confluency % + cells/cm²) and suspension (cells/mL + viability %)
Vessel presetsT-25, T-75, T-175, T-225, 6W, 12W, 24W, 48W, 96W, 10 cm dish, 15 cm dish, 1 L bioreactor, custom
Cell-line presetsHEK293, HeLa, CHO-K1, Vero, Jurkat (pre-filled density & doubling time)
Split outputsSplit ratio, suspension/media volumes per vessel and batch totals, total cells needed
Growth predictorForward time-to-confluence and inverse deadline seeding density with visual growth curve
Pipetting reserve0–50% (default 10%) added to total batch volumes and cell counts
Bench recipe cardNumbered hood instructions with single-vessel and total batch volumes
Passage logSession-only browser storage for passage number and cumulative population doublings
Runs in browserYes — no install
Account requiredNo
Data uploadNone — all calculations execute locally in the browser
AI assistantBuilt-in; explains fields, validates input, interprets passaging warnings

What it does

Passaging decisions made by eye and sticky notes lead to wrong split ratios, pipetting shortfalls, and missed passage windows. The Cell Passage Calculator converts current confluency or cell density, vessel format, and target seeding density into exact suspension and media volumes, split ratios, and step-by-step bench recipes—updated live on every keystroke.

Select Adherent or Suspension mode, pick a cell-line preset (HEK293, HeLa, CHO-K1, Vero, Jurkat) or enter custom density at confluence, and choose from T-flasks (T-25 to T-225), well plates (6-well to 96-well), culture dishes (10 cm, 15 cm), or 1 L bioreactors. Enter current confluency (%) or cell density (cells/mL), then set target seeding density or split ratio in bidirectional mode. A configurable pipetting reserve (0–50%, default 10%) accounts for tip dead volume across single or multi-vessel batches (up to 384 vessels).

The Growth Predictor tab forecasts hours to target confluency from doubling time, or back-calculates required seeding density for a fixed lab deadline—with an interactive growth curve and ±20% variation band. The session-only Passage Log tab tracks passage number and cumulative population doublings in browser storage. Copy protocol summaries, bench recipes, or CSV rows instantly—no account or server upload required.

Why researchers use it

  • Avoid passaging math mistakes and manual surface-area lookups
  • Switch between adherent (cells/cm²) and suspension (cells/mL) math instantly
  • Set split ratio or target density with bidirectional auto-sync
  • Scale media and suspension volumes across multi-vessel batches with reserve buffer
  • Predict time to confluence or back-calculate seeding density for deadlines
  • Copy hood-ready bench recipes and CSV rows without data upload

Best for

  • Routine T-flask passaging for HEK293, HeLa, or CHO-K1 at 70–90% confluency
  • Suspension culture passaging with viability-adjusted seeding volumes
  • Multi-vessel batch scaling with 10% tip reserve buffer
  • Scheduling next-passage timing from cell line doubling time
  • Back-calculating required seeding density to meet a Friday harvest deadline

When to use this vs alternatives

Choose this tool when daily cell passaging, volume scaling, and deadline prediction must live in one browser session. Use the Doubling Time Tracker when you have multi-time-point growth data and need linear regression fits or cumulative population doubling logs across weeks of passages. Use the Cell Seeding Density Calculator when scaling cell counts across multi-well assay plates prior to transfection or bioassays. Spreadsheets and vendor mobile apps still fit one-off manual calculations if you already trust a fixed template.

What makes it different

Vendor mobile calculators often lock outputs to milliliters, lack suspension support, and hide results behind multi-screen menus. Generic spreadsheets require manual surface area lookup and break when switching between ratio and density inputs.

The Pepkio Cell Passage Calculator combines adherent and suspension passaging, bidirectional ratio and density math, vessel presets through bioreactor scale, deadline growth prediction, vessel comparison, and session passage logging in one free browser workspace. Researchers switch when hand-calculated split ratios cause overgrowth or sparse seeding, or when passaging notes cannot be shared cleanly with lab mates.

How to get started

  1. Open the workspace and stay on the Split Calculator tab.
  2. Select Adherent or Suspension mode, pick a Cell-line preset (or enter custom density), and select a Vessel format.
  3. Enter Current confluency (%) or Cell density (cells/mL), then set Target seeding density or Split ratio.
  4. Set Vessel count and Pipetting reserve (%) to scale totals for your batch.
  5. Review Split ratio, per-vessel volumes, batch totals, and the step-by-step Bench Recipe card.
  6. Switch to the Growth Predictor tab to estimate hours until next passage or back-calculate seeding density for a deadline.

Frequently asked questions

How does the calculator compute split ratios for adherent cells?
Harvest cells per vessel equals current confluency (%) divided by 100, multiplied by vessel surface area (cm²) and cell density at 100% confluence (cells/cm²). Target cells per vessel equals target seeding density multiplied by surface area. Split ratio equals harvest cells divided by target cells. Suspension volume per vessel equals vessel working volume divided by split ratio.
How does suspension mode handle cell viability?
In suspension mode, viable cell density equals current cell density multiplied by viability percentage. Target cells per vessel equals target cell density (cells/mL) multiplied by working volume. Required suspension volume equals target cells divided by viable cell density. When viability drops below 80%, the tool displays an orange warning note that transfer volume has been increased to compensate for dead cells.
What is the pipetting reserve buffer percentage?
The reserve percentage (configurable from 0% to 50%, default 10%) adds a safety margin to total batch volumes and cell counts. This covers liquid remaining in serological pipette tips, tube dead volume, and meniscus losses during passaging. It scales total suspension and media volumes across multi-vessel preparations without altering per-vessel seeding targets.
How does the inverse growth deadline predictor work?
In inverse mode ("Seed for a deadline"), available doublings equal target deadline hours divided by doubling time. Required seeding density equals target final density divided by 2 raised to the power of available doublings. In forward mode ("When is it ready?"), required hours equal log2 of target confluency divided by seeding confluency, multiplied by doubling time.
Can I compare seeding requirements across different vessel formats?
Yes. Click the Compare Vessels toggle button in the left panel to open a side-by-side comparison table. This displays required cell stock volume, media volume, and total cells required across T-flasks, well plates, and dishes for your current culture inputs, making it easy to decide which vessel format fits your target assay schedule.
Can I use ChatGPT, Cursor, or another AI agent with this tool?
Yes. The workspace includes an in-browser AI assistant for validating inputs and interpreting passaging warnings. External agents can execute passaging calculations via API & MCP (/tools/developers) using the tool ID pepkio_confluency-split-passage-planner.

Client source code & registry

Open tool workspaceBack to tools

Last updated . Pepkio builds free lab calculators alongside bioinformatics CRO services.