Semi-Log · 1 Decade

About Semi-Log · 1 Decade

Semi-logarithmic paper with one logarithmic decade on the vertical axis (1, 2, 3, … 10) and a linear horizontal axis. Exponential phenomena plot as straight lines on this paper - a fact that made it indispensable to electrical engineers, biologists and economists for most of the 20th century. Further reading: A practitioner reading list covers the standards lineage in more depth.

Standards lineage

Formal definition in ISO 31-11:1992 mathematical signs and symbols.

A short history

Semi-log paper was patented in the 1890s and became the standard medium for electronic-engineering frequency plots before the digital oscilloscope made paper-based plotting obsolete.

Where designers reach for it

• Plotting exponential growth and decay curves
• pH titration and chemical-kinetics curves
• Frequency-response Bode plots (with log scaled appropriately)
• Cost-curve and learning-curve analysis

Printing this grid

Every variant on this page is delivered as a vector SVG with physical millimetre dimensions baked into the file, so a compliant printer driver will reproduce it at exact 1:1 scale by default. Choose the sheet size that matches your printer tray, set scaling to 100 % (never "fit to page"), and verify with the calibration check on our how-to-print guide. Buyer's guide: Comparing the major architectural scale rulers can help you pick the right physical scale rule to use over the printed grid.