Semi-Log Graph Paper
Semi-log graph paper has one linear axis and one logarithmic axis, which turns exponential growth into a straight line. Download semi-log templates in 7 sizes to plot population, bacterial growth and compound interest — free as PDF, PNG or SVG.
Key takeaways
- Semi-log paper has one logarithmic and one linear axis.
- Constant percentage growth becomes a straight line, so growth rates are easy to compare.
- All semi-log downloads are free and print at true scale.
Choose the finished page
Match the paper size to your printer, then pick portrait or landscape.
Configure the grid
Pick a theme, then fine-tune spacing, line color, dot size, opacity and margins.
Start from a practical setting
Jump to a ready template, then fine-tune the settings from there.
Semi-Log Graph Paper Templates
Ready-made semi-log graph paper pages — click a card to load the preset, or grab the PDF and PNG directly.
How to use semi-log graph paper
What is semi-log graph paper?
Semi-log graph paper has one linear axis and one logarithmic axis, usually a linear horizontal axis and a log-scaled vertical axis. This layout turns exponential growth into a straight line, which makes growth rates easy to read. Scientists use it for population, bacterial growth and financial trends that grow by a fixed percentage.
How a logarithmic scale works
A log scale stretches small values and compresses large ones, so each equal step multiplies by a fixed factor. The distance between 1 and 10 is the same as the distance between 10 and 100, which is why a doubling series plots as evenly spaced points.
Reading growth rates
When exponential data is plotted on semi-log paper, a constant growth rate appears as a straight line. A steeper line means faster growth, so two growth curves are easy to compare at a glance.
Choosing semi-log vs log-log
Use semi-log when one variable is linear and the other is exponential. Use log-log when both variables span many orders of magnitude, such as power-law relationships in physics and engineering.
Semi-Log Graph Paper sizes and spacing
| Option | What it gives you | Best for |
|---|---|---|
| 1 decade | One order of magnitude per cycle | Narrow growth ranges |
| 2 decades | Two orders of magnitude | Typical population and financial data |
| 3 decades | Three orders of magnitude | Wide-ranging scientific data |
Where semi-log graph paper is used
Biology and population
- Plot bacterial growth and doubling times
- Track population growth curves
- Compare infection and recovery rates
Finance and economics
- Chart compound interest and long-term returns
- Compare stock and index growth over decades
- Plot inflation and price trends
Science and engineering
- Graph earthquake magnitudes and energy release
- Plot sound levels and decibels
- Draw frequency-response and Bode plots — Log-Log Graph Paper
Semi-log paper vs Log-log paper
| Feature | Semi-log paper | Log-log paper |
|---|---|---|
| Logarithmic axes | One axis | Both axes |
| Straightens | Exponential growth | Power-law relationships |
| Slope means | Growth rate | The exponent in y = ax^b |
Semi-Log Graph Paper examples
Semi-Log Graph Paper Downloads
84 templates across 7 paper sizes and 6 spacings. Each card links the PDF, PNG and SVG for that exact grid.
A4 — 210 × 297 mm (8.27 × 11.69 in)
Letter — 216 × 279 mm (8.5 × 11 in)
A3 — 297 × 420 mm (11.69 × 16.54 in)
A2 — 420 × 594 mm (16.54 × 23.39 in)
Legal — 216 × 356 mm (8.5 × 14 in)
Tabloid — 279 × 432 mm (11 × 17 in)
Poster — 457 × 610 mm (18 × 24 in)
How to print semi-log graph paper
- Choose a paper size for your chart.
- Pick the linear-axis spacing and line color.
- Download the PDF for printing, or the SVG to edit.
- Print at 100% scale so the log cycles stay evenly spaced.
FAQ
What is semi-log graph paper used for?
It is used to plot exponential data such as population growth, bacterial counts, compound interest and earthquake magnitudes, where one value doubles at a steady rate.
What is the difference between semi-log and log-log paper?
Semi-log has one logarithmic axis and one linear axis. Log-log has logarithmic scales on both axes, for data that follows a power law.
Why does exponential data look straight on semi-log paper?
A logarithmic scale stretches small values and compresses large ones, so a constant percentage growth rate becomes a straight line that is easy to compare.
Which axis is logarithmic on semi-log paper?
Either can be, but the vertical axis is logarithmic on most printed sheets, while the horizontal axis stays linear.
Are these semi-log downloads free?
Yes. All semi-log PDF, PNG and SVG files are free to download and print with no login.
What is a decade on a log scale?
A decade is a tenfold change, such as from 1 to 10 or from 10 to 100. Each decade takes up the same amount of space on a logarithmic axis.