Calculator Inputs
Formula Used
1) Cross-sectional areaA = π × d² / 4
2) Linear velocityu = F / A, after converting flow to cm³/min and area to cm².
3) Flow scaling for equal linear velocityF₂ = F₁ × (d₂² / d₁²)
4) Column volumeVcol = π × (ID/10)² / 4 × (L/10) in mL, using mm to cm conversions.
5) Void volumeVvoid = Vcol × ε, where ε is porosity.
6) Dead timet₀ = Vvoid / F
7) Injection volume scalingVin j,2 = Vinj,1 × (d₂² × L₂) / (d₁² × L₁)
8) Pressure estimateP₂ ≈ P₁ × (L₂/L₁) × (F₂/F₁) × (d₁²/d₂²) × (dp₁²/dp₂²)
These relationships are widely used for quick method-transfer estimates. Real systems can deviate because of solvent viscosity, temperature, extra-column volume, frit design, and packing differences.
How to Use This Calculator
Enter the current method flow rate and source column dimensions first. Then provide target column dimensions and particle size for the method you want to transfer.
Set porosity if you know your packing characteristics. Leave the default if you only need a fast estimate for routine development work.
Add source pressure, injection volume, and dwell volume when you want a more complete transfer report. These extra values help estimate pressure behavior, scaled injections, and gradient delay changes.
Press Calculate Flow. The calculator places the results directly below the header and above the form, then displays a Plotly chart, a comparison table, and export options.
Use the CSV file for data review or system integration. Use the PDF button to save a report for validation notes, development logs, or client handoff.
Example Data Table
| Scenario | Source Setup | Target Setup | Recommended Flow | Notes |
|---|---|---|---|---|
| Method transfer to narrow bore | 1.00 mL/min, 4.6 × 150 mm | 2.1 × 100 mm, 1.8 µm | 0.2084 mL/min | Maintains linear velocity while reducing solvent usage. |
| Analytical to microbore | 0.80 mL/min, 4.6 × 100 mm | 1.0 × 100 mm, 3.0 µm | 0.0378 mL/min | Useful for low-volume systems and MS-friendly methods. |
| Upscaling for preparative screening | 0.25 mL/min, 2.1 × 50 mm | 10.0 × 50 mm, 5.0 µm | 5.6689 mL/min | Flow rises sharply with larger diameter columns. |
Frequently Asked Questions
1) What does this calculator actually estimate?
It estimates target flow rate, linear velocity, column volume, void volume, dead time, injection scaling, gradient delay, and approximate pressure for HPLC method transfer.
2) Why is flow scaled with diameter squared?
Column cross-sectional area changes with diameter squared. Matching linear velocity usually requires the volumetric flow to scale by the same diameter-squared ratio.
3) Does equal linear velocity guarantee identical chromatography?
No. It is a practical starting point. Retention, efficiency, selectivity, and pressure can still shift because of particle size, dwell volume, gradient behavior, solvent viscosity, and system dispersion.
4) How accurate is the pressure estimate?
It is an approximation for planning. Actual backpressure also depends on mobile phase composition, temperature, tubing, frit design, packing structure, and instrument hardware limits.
5) Why do I need porosity?
Porosity helps estimate void volume and dead time. If you do not know it, a common packed-column estimate near 0.68 is often used for quick calculations.
6) Can I use this for UHPLC transfers?
Yes, but validate pressure carefully. Smaller particles and narrow columns can push systems near hardware limits, especially when gradients or viscous solvents are involved.
7) What is scaled injection volume used for?
It helps preserve sample loading relative to column volume. This can reduce peak distortion when moving between larger and smaller columns.
8) Why include a Plotly graph?
The graph makes diameter-based flow scaling easier to review. It quickly shows how recommended flow changes across common HPLC column sizes.