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SWRC Fit can fit several soil hydraulic models to measured soil water retention data. Copy your soil water retention data in the textbox below and press "Calculate" button. Before you use your original data you can see how it works by selecting a sample data from the pulldown menu.

Model selection

Brooks and Corey
van Genuchten
Fredlund and Xing

Figure option
Show only one model

Soil Water Retention Curve

Show more options (Update on 2024-06-04)

Calculation options

  • Fit θr θr = Fit θr for unimodal and θr = 0 for bimodal
  • Fit θs θs = θmax θs =
  • Upper limit of θs / θmax =
  • Upper limit of λ1, λ2 =
  • Upper limit of n1, n2 =
  • Lower limit of σ1, σ2 =

[New] Output options

Corrected AIC
1σ uncertainty of parameters
Correlation matrix

When you calculate, setting is saved in your web browser.


Format of input data

Sample output

Sample output


Please cite this paper when you publish your work using this program, SWRC Fit or unsatfit. SWRC Fit uses unsatfit library.



Please send questions and bug reports to Q&A at unsatfit Discussions. Get GitHub account, sign in, and press the green "New discussion" button. I will reply by comment. It is preferable to send your question publicly this way, because other people having the same question can find answer on the web. However, if your question is confidential, for example when it includes your unpublished data, please contact me by email. You can find my email address in this paper.

SWRC Fit with unsatfit version 5.2 created by Katsutoshi Seki running with Python 3.11.2 on Linux. Run local server.

This service is running for 17 years