Run the simulation, activate the waveform viewer, choose File → Export Data as Text (older releases may show File → Export), select the traces and simulation steps, and save the result. LTspice normally writes a tab-delimited text file—not a comma-separated CSV—so import it with the Tab delimiter before saving a true CSV.
Export waveform data from LTspice
- Open the schematic or netlist and run the required analysis.
- Click the waveform viewer so it is the active window.
- Add the required node voltages, device currents, or calculated traces. Use Add Trace when necessary.
- Open the viewer’s File menu and select Export Data as Text. In older LTspice versions the command is labeled Export. See the older procedure in Analog Devices’ export guide and the current label in its support response.
- In the export dialog, select the traces and, where offered, the simulation steps.
- Use Browse to choose the destination and filename.
- Click OK, then inspect the first lines of the saved file before importing it.
Remove unneeded traces before exporting. This keeps the file smaller and makes later parsing less ambiguous.
What LTspice exports: text, RAW, and PLT files
| File | Contains | Use |
|---|---|---|
| Exported text | Selected waveform values in a human-readable, usually tab-delimited table | Excel, Python, MATLAB, GNU Octave, and other analysis tools |
.raw |
LTspice simulation-result data, normally binary | Reopening results in LTspice or programmatic raw-file readers |
ASCII .raw |
The LTspice raw-data structure written as text with -ascii |
Automation or modest datasets; it is not CSV |
.plt |
Plot configuration, selected traces, and viewer layout | Restoring a plot; it does not contain waveform samples |
Renaming a binary .raw file to .csv changes only its extension; Excel still cannot interpret the binary contents. The distinction between plot configuration and data is documented in LTspice’s PLT help.
Is the LTspice export a CSV?
Usually not. The normal GUI export is tab-delimited text, as described by Analog Devices support. A .txt or .tsv extension makes that delimiter explicit. Changing the extension to .csv does not convert tabs to commas.
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Open it correctly in Excel
- Use Data → From Text/CSV (the exact label varies by Excel version).
- Choose Delimited and select Tab.
- Check the preview for separate columns and correctly interpreted scientific notation such as
1.2E-03. - Load the table, then use File → Save As and choose CSV if a comma-separated file is required.
If Excel puts everything in one column, reopen the import dialog and explicitly select Tab. Locale settings can also affect decimal separators, so verify numeric columns before analysis.
Convert with Python
import csv
with open("ltspice_export.txt", newline="") as source:
rows = csv.reader(source, delimiter="t")
with open("ltspice_export.csv", "w", newline="") as destination:
writer = csv.writer(destination)
writer.writerows(rows)For investigation of headers and stepped data, pandas is convenient:
import pandas as pd
data = pd.read_csv("ltspice_export.txt", sep="t")
print(data.head())
print(data.columns)Inspect the file first: headers, blank lines, run labels, and the independent-variable column differ by analysis and release. Blindly replacing tab characters can corrupt text containing punctuation or localized number formats.
Export selected voltages, currents, and expressions
The export dialog lists traces available in the waveform viewer. You can export node voltages, component currents, and calculated expressions—not just raw node signals.
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- Add the expression to the plot, for example
V(out)-V(in)orV(out)*I(Rload). - Confirm that the expression is plotted and that its label is correct.
- Open the export command and select that calculated trace.
- Check the output header after saving.
Waveform arithmetic and user-defined functions are described in the waveform-viewer documentation. Expression syntax and available functions depend on the analysis and LTspice release.
Exporting .step and other multiple-run results
For a .step, Monte Carlo, or worst-case analysis, select the required runs in the export dialog when that option is available. LTspice commonly writes runs sequentially or groups them by step rather than creating a tidy spreadsheet with one column per run. The layout can vary; an Analog Devices discussion records this stepped-export limitation.
- Keep the step parameter or run label from the exported header.
- Inspect several lines from every run before writing a parser.
- Do not assume all runs have identical sample points or row counts.
- Reshape the result in Excel, Python, MATLAB, or Octave only after identifying the actual layout.
A parser should group rows by the run markers present in your file, not by a hard-coded row count.
How analysis type changes the exported columns
- Transient: time-domain values, normally sampled at adaptive simulator time points.
- AC: frequency-domain values; the plotted expression may be magnitude, phase, real, or imaginary.
- DC sweep: the swept source or parameter is the independent variable.
- Noise: frequency-domain noise quantities using analysis-specific labels.
- FFT: frequency-domain results derived from time-domain data.
- Stepped analyses: multiple datasets grouped in the exported text.
Therefore, do not write a universal importer that assumes the first column is always named time.
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Get equally spaced samples for FFT or filtering
Transient simulation uses adaptive time stepping, so ordinary export does not guarantee a fixed interval. FFT routines, digital filters, control calculations, and numerical differentiation may require uniform samples.
- Export the original adaptive-step data so the source values are preserved.
- Choose a sampling interval appropriate to the signal and analysis bandwidth.
- Resample explicitly in Python, MATLAB, or another numerical tool, documenting the interpolation method.
LTspice’s documented FFT workflow interpolates data to equally spaced time steps; exporting the FFT result can provide equally spaced data, and the help also describes applying the FFT process twice to recover equally spaced time-domain data. Treat that as an LTspice-specific workaround, not a guarantee of uniform spacing in every export. See Exporting Waveform Data.
Export an ASCII RAW file from the command line
For Windows automation, a typical batch invocation is:
LTspice.exe -ascii -b circuit.cir-ascii requests ASCII raw output and -b runs in batch mode. The -run switch is also listed in Analog Devices’ current shortcut reference. The executable path and accepted schematic/netlist workflow depend on the operating system and release; an .asc schematic is not interchangeable with a .cir netlist in every invocation.
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ASCII output is usually larger and slower than binary output and still follows LTspice’s raw-data organization, not a spreadsheet format. The raw format is not presented as a fully specified public interchange standard; check that any third-party reader supports your LTspice version. See the Analog Devices raw-format discussion.
When to use GUI export or a RAW-file reader
| Approach | Best for | Trade-offs |
|---|---|---|
| GUI text export | One-off work, a few traces, spreadsheet review | Manual selection; tab-delimited output; stepped data may need reshaping |
| ASCII RAW with batch switches | Scripted simulations and modest datasets | Larger, slower files; still requires a raw-format parser |
| Binary RAW reader | High-volume automation, all traces and metadata | Requires a compatible library and version-aware format handling |
Use GUI export when a simulation is already open and you need selected traces. Use batch simulation and raw-file parsing when reproducibility, scale, or unattended processing matters.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Preserve waveform detail
LTspice can compress waveform data while writing .raw files. The compression is lossy within relative and absolute tolerances. For precision-sensitive waveform preservation, especially with FFT or .four, rerun with:
.options plotwinsize=0This disables that waveform-storage compression mechanism; it does not remove solver tolerances, numerical error, or modeling error. Advanced controls include:
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.options plotreltol=<value>
.options plotvntol=<value>
.options plotabstol=<value>Tighter settings can increase file size and simulation cost. Details are in LTspice’s compression reference.
Recover data and fix common export problems
| Symptom | Likely cause | Fix |
|---|---|---|
| No “Export Data as Text” command | The waveform viewer is not active, no result is plotted, or the release uses “Export” | Run the simulation, click the viewer title bar, and reopen its File menu. Older versions use File → Export. |
| Excel shows one column | Tab delimiter was not detected | Import as Delimited and select Tab. |
| Stepped data is confusing | Runs are concatenated or grouped sequentially | Inspect headers and labels, then group rows by run before reshaping. |
| RAW file looks unreadable | It is binary | Use GUI text export, rerun with -ascii, or use a compatible raw reader. |
| Curve appears less precise | Waveform compression | Rerun with .options plotwinsize=0 when appropriate. |
| Waveform disappears after closing LTspice | Automatic RAW deletion is enabled | Check the operation settings and raw-data directory; rerun if the file was deleted. The .plt file cannot restore samples. |
| Python or MATLAB import fails | Headers, tabs, labels, non-time independent variables, or multiple runs | Open the text file, identify its structure, then configure the importer accordingly. |
LTspice operation settings include automatic deletion of raw files; the behavior is described in Operation. If the raw file is gone, there is no waveform data to export without rerunning the simulation.
Numerical data versus pictures of plots
Copying or exporting a plot image is suitable for a report, but it contains no numerical samples. Use Export Data as Text or a RAW-file workflow for values. A PWL file is a separate reverse workflow: prepared text data can be fed back into LTspice as a piecewise-linear source, as shown in Analog Devices’ PWL article.
Which external tool should you use?
- Excel: quick inspection, small or moderate files, and basic charts.
- Python: free, repeatable conversion, resampling, filtering, and batch processing.
- MATLAB: established engineering teams needing advanced numerical workflows.
- GNU Octave: a free MATLAB-compatible option for many analyses.
LTspice’s product page currently lists Windows 10/11 x64 version 26.0.2, with models shown as updated May 16, 2026; other platforms or releases may display different labels and builds. See Analog Devices LTspice.
Frequently Asked Questions
Can LTspice export all .step runs?
The export dialog can include selected simulation steps, but the resulting text commonly groups runs sequentially. Inspect the headers and reshape the data instead of assuming one column per step.
Can I export a waveform after closing LTspice?
Only if the corresponding .raw file still exists. If automatic RAW deletion removed it, rerun the simulation; a .plt file stores plot settings, not samples.
How do I export from LTspice on macOS?
Use the waveform viewer’s export command where available; menu labels and command-line options can differ by platform and release. If a menu item is missing, activate the viewer and check the version-specific documentation.
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