What this site does. You bring a table of numbers, it gives you
numbers back. This page fits a slow baseline under your data - a constant, a
straight line or a polynomial - and subtracts it, so the signal sits on a flat
zero. It runs entirely in your browser — nothing is uploaded, nothing is stored.
If you want the reasoning rather than the answer, the
detrending article walks through each
method and where each one fails.
Peaks pull every method on this page up towards them, so the baseline runs too
high under large peaks. For spectra and chromatograms, use asymmetric least
squares (ALS) on the advanced calculator.
- Paste your data into the Input grid — straight from a
spreadsheet, or as CSV/TSV text — or import a CSV/TSV file.
Column x, then up to three y columns. Up to 5,000 rows.
- x may be unevenly spaced and in any order: rows are sorted by x. A row with
no number in x is skipped; a blank y cell is skipped for that column only.
- Pick a method. Mean removes a constant, linear a straight
line, polynomial a curve of order 1 to 5.
- Real time range — try orders live on the polynomial order box.
- ▲▼ buttons or the mouse wheel over the
box: the order moves by one and the result is recomputed at once - no need
to press detrend.
- Digit wheel: over the box, the wheel steps the digit just
left of the mouse pointer.
- Limits: the order stays within 1 to 5; a typed order
outside that range is set to the nearest limit.
- Typing or the arrow keys change the box only; press
detrend to recompute.
- Press detrend. The upper chart shows your data as dots and
each fitted baseline as a line in the same colour; the lower chart shows the
detrended data over a zero line.
- Read the result. The Output grid lists x, then the baseline
and the detrended value for each y column. Baseline plus detrended equals your
input. Export saves the Output grid as a CSV/TSV file.