About semi-log graph paper
Semi-log paper turns exponential growth into a straight line. The Y axis is divided into logarithmic decades while X stays linear, which keeps data spanning several orders of magnitude readable. It is standard in science, biology and finance.
One axis is logarithmic and the other linear. Plotting exponential data — bacterial growth, radioactive decay, compound interest — turns a curve into a straight line whose slope gives the rate, which is why semi-log paper is a lab and finance staple.
Each log decade repeats the 1–9 spacing, so pick the number of decades to cover your data's range (10 to 10,000 is three decades). The linear axis carries time or the evenly spaced variable.
Great for
- Exponential growth and decay
- pH, absorbance and titrations
- Signal and frequency basics
- Finance and population data
Common questions
How many decades do I need?
Count the powers of ten your data spans — 1 to 1000 is three decades. Set that many so everything fits on one sheet.
Which axis is logarithmic?
The Y axis carries the logarithmic decades and X stays linear, the usual arrangement for plotting growth and decay over time.
Guides for this paper
Printing at the right size
Every sheet is drawn in real units, so it prints true to size as long as you print at 100%. In the print dialog, set the scale to 100% and turn off “Fit to page” or “Shrink oversized pages” — then a 5 mm square really measures 5 mm. Download a vector SVG to edit later, a PNG at up to 600 dpi, or a ready-to-print PDF. Everything is generated in your browser, nothing is uploaded, and every sheet is free to print for personal, classroom and commercial use. See the guide to printing at true size or the FAQ for more.