HPLC Gradient Mobile Phase Calculator

Set the flow rate and gradient program, then press Run to calculate mobile phase A and B volumes. Move the time slider to view consumption during the run.

1. Gradient Conditions

Flow rate (mL/min)

Number of runs

Extra solvent (%)

Gradient Program

Set the time (min) and solvent B (%). Solvent A = 100 − solvent B. Composition changes linearly between points.

2. Required Mobile Phase

Solvent A (mL)—

Solvent B (mL)—

Solvent A / B consumption ratio
0%

Total required: —

Run time: —

A / B: —

3. Gradient Curve

The vertical line marks the selected time. Drag the slider or tap the graph to inspect solvent consumption for one run.

Time: — min

Composition at selected time: —

Consumed A (mL)—

Consumed B (mL)—

Total consumed: —

How Does the Mobile Phase Calculator Work?

At constant flow rate F (mL/min), total consumption at time t is F × t. Solvent B consumption for each linear gradient segment is calculated using the average %B; solvent A is the remaining volume.

Solvent B (mL) = Σ [F × (t₂ − t₁) × (%B₁ + %B₂) / 200].
Solvent A (mL) = total volume − solvent B volume.

The required volumes include the number of runs and extra solvent percentage. The time slider shows consumption for one run without extra solvent. Include re-equilibration in the gradient if needed; purging, priming and reservoir dead volumes are not modeled separately.