Hydrochart is a free, browser-based Gibbs diagram maker. It plots total dissolved solids against the Na/(Na+Ca) and Cl/(Cl+HCO₃) weight ratios, placing samples in the precipitation-, rock- or evaporation-dominance fields. Everything runs locally; your data never leaves your device.
Make a Gibbs diagram in three steps
Load your data
Open the plotter and drop in a CSV or Excel file of major-ion concentrations, or paste a table. Column headers are matched automatically.
Get the diagram
Hydrochart computes the Gibbs ratios and uses your TDS (or estimates it from the ions) to place every sample in the correct dominance field.
Export it
Download the finished diagram as vector SVG or PNG — sharp at any size, ready for a report, thesis or paper.
What a Gibbs diagram shows
A Gibbs diagram plots TDS on a logarithmic axis against a weight ratio — Na/(Na+Ca) for the cation version or Cl/(Cl+HCO₃) for the anion version. Where samples plot reveals the dominant control on their chemistry: low-TDS, high-ratio water in the precipitation field; mid-TDS, low-ratio water in the rock-weathering field; and high-TDS, high-ratio water in the evaporation field.
What data do I need?
Supply your major ions in mg/L and Hydrochart converts to milliequivalents and does the rest:
| Group | Ions |
|---|---|
| Cations | Calcium (Ca), Magnesium (Mg), Sodium (Na), Potassium (K) |
| Anions | Bicarbonate (HCO₃) and Carbonate (CO₃), Sulfate (SO₄), Chloride (Cl) |
| Optional | TDS, pH and EC — used for labelling and QA, estimated when absent |
Not sure of the layout? Download the CSV template and paste your values into it.
Why use Hydrochart
- Genuinely free. Create and view unlimited Gibbs diagrams with no account. Free exports carry a small watermark; Pro (USD $29/year) removes it and adds CSV export.
- Nothing is uploaded. The whole tool runs client-side in your browser, so confidential monitoring data stays on your machine.
- Publication-ready output. Vector SVG and PNG export, with drag-to-place sample labels and leader lines for clean figures.
- One dataset, every diagram. The same file also plots Piper, Stiff, Schoeller, Chadha, Durov and Gibbs — no re-entry.
- Built-in quality control. Every analysis gets a cation–anion charge-balance error, flagged when it exceeds ±5%.
New to Gibbs diagrams?
If you want the theory before you plot, read the companion guide: the Gibbs diagram explained. It covers what the plot shows and how to interpret where your samples fall.