SumatraPDF Print Scaling Is Wrong: How to Fix Size and Margins

When SumatraPDF prints a page too small, too large, clipped, stretched, off-center, or with unexpected margins, the problem is usually not printer connectivity. It is more often a mismatch between the document page size, SumatraPDF's scaling choice, the printer driver's selected paper, and the printer's physical printable area. Forms, labels, mixed-size PDFs, and documents created for Letter paper but printed on A4 are especially likely to expose these differences.

The safest way to troubleshoot SumatraPDF print scaling is to change one setting at a time and print only one representative page. Once the page has the correct physical dimensions, margins, orientation, and position, stop changing settings and use that combination for the remaining pages.

1. Confirm the Symptom With a One-Page Test

Start by identifying exactly what is wrong. A page that is uniformly smaller than expected requires a different fix from a page that is the correct size but clipped at one edge. Likewise, an off-center label may indicate printable-area handling rather than scaling.

1.1 Choose a useful test page

Open the affected document in SumatraPDF and select one page containing features you can measure or easily compare. Good choices include a form with a known box size, a shipping label, a page with a visible border, or a page containing content close to every edge.

In the print dialog, print only the current page or enter that single page number. Do not print the full document while experimenting. A one-page test saves paper and makes it easier to compare each change.

1.2 Classify the result before changing anything

• Everything is too small: Fit scaling may be reducing the page to the printer's printable area, or the driver may be applying another reduction.
• Everything is too large or cropped: The document may be larger than the selected paper, or enlargement may be enabled.
• Only the edges are missing: The content probably extends outside the printer's printable area.
• The page is off-center: Centering may be disabled, or the printer has unequal hardware margins.
• The shape is distorted: A printer-driver setting may be stretching content non-proportionally.
• Some pages are correct and others are not: The file may contain mixed page sizes or orientations.

Success at this stage means you can describe the problem consistently and reproduce it with one page. If the result changes between identical tests, first verify the selected printer, paper source, and driver settings before investigating SumatraPDF preferences.

2. Check SumatraPDF Page Scaling and Paper Handling

The most important control is the relationship between the PDF page and the printer's printable area. Paper size and printable area are not the same thing. A printer may accept A4 or Letter paper while still being unable to place ink or toner along every edge.

2.1 Understand shrink, fit, stretch, and noscale behavior

SumatraPDF's printing options and command-line printing terminology can include behaviors such as shrink, fit, and noscale. The wording visible in a dialog can vary with the printing path, but the underlying choices are straightforward.

• Shrink: Reduces a page only when it is too large for the available printable area. A smaller page should not be enlarged. This is useful when you want to prevent clipping without making small pages larger.
• Fit: Scales the page to fit the printable area. It can reduce oversized pages and enlarge smaller ones. Proportions should remain intact, but the physical size of forms and labels can change.
• Stretch: Usually describes enlargement to fill more of the available space. In some printer interfaces, stretching may be part of a fit option. Avoid any driver option that stretches width and height independently because circles can become ovals and measured dimensions can become inaccurate.
• Noscale: Prints at the document's intended size, commonly described as 100 percent or actual size. Content outside the printer's printable area may be clipped.

If the document is a label, ruler, template, preprinted form, sewing pattern, or other size-sensitive item, start with noscale or the equivalent 100 percent setting. Measure the result. If a 100 mm line prints as 100 mm, scaling is correct even if an edge is clipped. Clipping must then be addressed through paper choice, orientation, positioning, or a printer capable of borderless output.

If the goal is simply to keep an ordinary document fully visible, use shrink or fit. Use shrink when you do not want small pages enlarged. Use fit when filling more of the available page is desirable and exact physical dimensions do not matter.

2.2 Check the selected paper size

Open the printer properties from the print dialog and verify the paper size. It must match both the paper actually loaded and the intended output. A Letter document printed with A4 selected, or an A4 document printed with Letter selected, may be reduced, shifted, or clipped because the two sizes have different dimensions.

Also check orientation. A landscape source page sent to a portrait paper configuration may be rotated, reduced significantly, or clipped depending on the driver. If the driver offers automatic orientation, test it against an explicitly selected portrait or landscape setting.

Success means the paper size shown in the printer properties matches the loaded paper and the document prints at the intended scale. Once it does, do not compensate by adding an unrelated percentage adjustment.

2.3 Center the page horizontally

If the page is the correct size but sits too far left or right, enable horizontal centering where that option is available. Centering is particularly useful for labels, smaller source pages, and documents whose page size does not fill the selected sheet.

Remember that printers can have unequal non-printable margins. Mathematical centering on the full sheet and centering within the printable area can therefore look slightly different. If a label must align with precut stock, use a one-page test and the label manufacturer's template rather than relying only on visual centering.

Success means the left and right placement is suitable without changing the measured size of the printed content. Stop adjusting scale once size is correct. Use positioning or the correct media definition for remaining alignment changes.

3. Check the Document, Windows, and Printer Driver

If SumatraPDF's scaling choice looks correct but the output remains wrong, inspect the factors that define the page before and after SumatraPDF sends it to Windows.

3.1 Identify the source page size

A document can look normal on screen even when its internal page dimensions are unusual. Check whether the source was created as A4, Letter, Legal, a custom label size, or an oversized drawing. If possible, compare it with the page size shown by the application that created the file.

Do not assume every page in one PDF has the same dimensions. Scanned packets, combined reports, and PDFs assembled from several sources often contain mixed page sizes. A single scaling rule may make one page correct and another too small.

For a mixed-size file, test one page from each size group. You may need to print page ranges separately, changing the paper or scaling choice between groups. Success means each group prints consistently without forcing one compromise setting onto every page.

3.2 Remove duplicate scaling in the printer driver

Printer drivers can apply their own scaling after an application has prepared the print job. Open printer properties and look for settings such as fit to page, scale to paper size, zoom, reduce or enlarge, borderless expansion, booklet, poster, multiple pages per sheet, or custom percentage.

For troubleshooting, disable these features and select one page per sheet at 100 percent in the driver. Let SumatraPDF control the initial scaling. If the driver and SumatraPDF both fit the page, the output can be reduced twice or otherwise repositioned.

Borderless printing deserves special attention. Some drivers enlarge a page slightly so ink extends beyond the paper edge. That deliberate expansion can crop text, label borders, or registration marks. Disable borderless expansion when exact dimensions matter.

Success means the driver is using the correct paper size with no unexpected enlargement, reduction, booklet layout, or multi-page layout. If the test page is now correct, leave the driver neutral and control scaling from one place.

3.3 Compare another viewer without changing the document

Print the same single page from another trusted PDF viewer using the same printer, paper size, orientation, and scaling behavior. This is a diagnostic comparison, not necessarily a permanent switch.

• If both viewers produce the same wrong size, focus on the document dimensions or printer driver.
• If only SumatraPDF produces the wrong size, focus on SumatraPDF's selected print behavior, saved settings, or rendering path.
• If the paper size changes between applications, the Windows driver or application-specific printer preferences may be retaining different defaults.

Some document formats are converted or rendered differently before printing. If an eBook, comic, XPS, DjVu, CHM file, or image prints incorrectly, test a simple PDF as a control. External components such as Ghostscript or codecs may matter for certain formats or workflows, but they are not a routine fix for ordinary PDF page scaling. Do not install unrelated components unless the affected format or an explicit error points to them.

3.4 Check document permissions when printing is unavailable

Scaling symptoms should not be confused with a document that blocks printing. Some protected documents restrict printing through their permissions. Respect those restrictions and obtain an authorized printable copy from the document owner if necessary. Permissions generally do not explain a job that prints successfully but at the wrong size.

4. Inspect SumatraPDF-settings.txt Safely

SumatraPDF stores preferences in a text settings file. Inspecting this file can help when a print-related choice keeps returning, settings do not persist, or installed and portable copies behave differently. It should not be the first step when the printer paper size is plainly wrong.

4.1 Locate the settings file for the copy you are running

Installed and portable copies may use different settings locations. A portable copy can keep its settings near the executable when that location is writable, while an installed copy commonly uses the user's application-data location. If you have multiple SumatraPDF executables, confirm which one opened the document before editing anything.

Close SumatraPDF before changing the file so the program does not overwrite your edits when it exits. Make a backup copy named something such as SumatraPDF-settings-backup.txt.

4.2 Inspect rather than guess

Open SumatraPDF-settings.txt in a plain-text editor. Look for print-related preferences or obviously unusual values, but do not invent setting names or copy random configuration blocks from old forum posts. Settings can change over time, and unsupported entries may be ignored.

If settings fail to persist, check whether the file or its folder is read-only and whether the current Windows account can write there. This is particularly relevant when a portable copy is stored under a protected folder such as Program Files or on read-only media.

To reset safely, close SumatraPDF and rename the settings file rather than deleting it. Start SumatraPDF again so it can create a fresh configuration. Retest one page before restoring any preferences. If the scaling problem remains with fresh settings, the cause is more likely the source page, Windows printer configuration, or driver.

Success means a clean settings file produces stable, predictable print choices. If renaming the file changes nothing, restore the backup if needed and stop modifying configuration files.

5. Run a Clean Temporary Test Before Reinstalling

Reinstalling rarely fixes a paper-size mismatch because printer-driver preferences and source document dimensions remain unchanged. A clean temporary test provides better evidence.

5.1 Use a controlled test sequence

1. Close all SumatraPDF windows.
2. Keep a backup of the current settings file.
3. Run a separate official portable copy from a writable temporary folder, or test with a newly generated settings file.
4. Open a simple one-page PDF with a known A4 or Letter page size.
5. Select the intended printer and verify its paper size and orientation.
6. Disable scaling in the driver and choose the appropriate scaling behavior in SumatraPDF.
7. Print one page and measure it if exact size matters.

If the clean copy prints correctly, compare its print choices and settings location with the original installation. A stale preference, different executable, or unwritable portable configuration is likely involved. If both copies print incorrectly in the same way, reinstalling SumatraPDF is unlikely to help. Concentrate on the driver, paper definition, and source file.

Success means you can reproduce either a correct result or the same failure under controlled conditions. Stop once you have isolated the layer responsible. Repeatedly reinstalling applications, drivers, and codecs at the same time makes the cause harder to identify.

6. Quick Fix Checklist

• Print one representative page, not the whole document.
• Confirm whether the page is reduced, enlarged, clipped, distorted, or merely off-center.
• Match the printer driver's paper size to the paper actually loaded.
• Use noscale or 100 percent for labels, forms, templates, and measured drawings.
• Use shrink to reduce only oversized pages without enlarging smaller pages.
• Use fit when exact physical size is unimportant and all content must remain visible.
• Disable driver-level fit, zoom, booklet, poster, and multiple-pages-per-sheet options.
• Disable borderless expansion when dimensions or edge marks must remain accurate.
• Enable horizontal centering when the page size is correct but placement is wrong.
• Test different page-size groups separately when a document contains mixed pages.
• Compare one page in another viewer to separate application behavior from driver behavior.
• Rename the settings file only after backing it up and closing SumatraPDF.

7. Frequently Asked Questions

7.1 Why does SumatraPDF print smaller than the preview?

The preview may show the full document page without representing the printer's non-printable edge margins. Fit or shrink behavior can reduce the page so all content lies inside the printable area. The printer driver may also apply an additional fit-to-page reduction. Verify paper size, disable driver scaling, and compare fit with noscale on one page.

7.2 Which setting should I use for labels and forms?

Use noscale, actual size, or 100 percent because labels and forms depend on physical dimensions. Disable driver scaling and borderless expansion. Measure a known element on the first test page before printing the full batch. If the size is correct but placement is wrong, adjust centering or the media definition rather than scale.

7.3 Why is the page clipped at 100 percent?

The source content probably extends beyond the printer's printable area, or the source page is larger than the selected paper. A standard printer may not be able to print to every edge. Use shrink if preserving all content matters more than exact size, select a larger sheet, or use supported borderless printing when appropriate.

7.4 Why are only some pages scaled incorrectly?

The document may contain mixed page sizes or orientations. Inspect representative pages and print size groups separately if necessary. Also check whether automatic orientation or paper selection changes between pages.

7.5 Does reinstalling SumatraPDF fix wrong margins?

Usually not. Wrong margins are more commonly caused by printable-area limits, mismatched paper sizes, duplicate scaling, or saved preferences. Run a clean portable or fresh-settings test first. Reinstall only if the controlled test points to damaged application files rather than configuration or driver behavior.

7.6 When should I stop troubleshooting?

Stop when one test page has the intended measured size, no unacceptable clipping, the correct orientation, and suitable horizontal placement. If exact size is correct but unavoidable hardware margins remain, further scale changes will make the document inaccurate. At that point, use different paper, a different printer capability, or an approved document layout rather than continuing to alter scaling.