This is technical document-preparation guidance, not immigration advice. Thailand e-Visa instructions can depend on the visa type, mission and application. Follow the current instructions shown for your own upload slot; no live application was tested for this guide.

Start with the upload slot—not a number from another application

Do not assume every Thailand e-Visa application has the same file-size cap or accepts the same format. A 3 MB per-file limit and JPG/JPEG passport-page instructions appear in specific published material, including a Thai government-hosted guide for participants in the 2026 IMF and World Bank Annual Meetings and mission guidance from the Royal Thai Embassy in Prague. Those sources are useful examples, but they do not establish one universal rule for every applicant, visa category or Thai mission.

Before preparing a file, record three things from your own application: the upload field's name, its accepted file types, and the maximum size shown there. If the field or mission checklist differs from a general guide, use the current application instruction.

The Thai e-Visa portal provides the application workflow. The official English user manual explains how to use the system; the mission-specific checklist and the live upload field remain the place to confirm current technical requirements.

What the cited guidance says—and what it does not prove

Information about Example upload rule in cited guidance by What to do with it
Example upload rule in cited guidance	What to do with it
Some guidance gives a 3 MB maximum for each file	Treat 3 MB as the limit only when your own upload slot or mission instruction shows it.
Certain instructions request the passport biodata page as JPG/JPEG	Do not submit a PDF to a field explicitly marked JPG/JPEG. Other applications may specify a different format.
Photo instructions use image formats and their own photo criteria	Check the current mission's size, dimensions, background and framing rules; a file-size check alone is not enough.
Supporting evidence may be accepted as JPG, JPEG or PDF in the cited examples	Use only an extension listed for the exact field. Do not infer that every evidence slot accepts all three.

The 2026 Annual Meetings document is specifically for event participants. The Prague embassy document is mission guidance. The portal manual explains the application workflow but is not a universal, current limit table for every route. Read each source in its scope, then follow the requirements on your own application.

Keep image uploads and PDF documents separate

A passport biodata page, a visa photograph and supporting evidence are different upload types. A portal may ask for the passport page as an image while accepting a PDF for a bank statement—or it may specify something else. Don't merge everything into a single PDF just because the documents belong to one application.

Passport biodata page: use the format named by the field. If it explicitly asks for JPG/JPEG and you have a PDF scan, export the page as an image and check that all four edges, the portrait, passport number and machine-readable zone remain clear.
Applicant photograph: follow the photo-specific instructions for the mission and visa type. Keep the required crop and image dimensions; a file being small enough does not make a photo compliant.
Supporting documents: keep each document or evidence group in the exact structure requested. Use PDF only where the slot accepts it. If a multi-page record must be one document, merge only those pages that belong together.

The PDF merge tool combines whole supported PDFs when the application permits one PDF in a slot. It does not turn images into PDFs or determine what the mission accepts.

Prepare files without losing required evidence

Check the current field and mission checklist. Note accepted extensions, maximum bytes, number of files and whether the slot represents one document or a category bundle.
Keep the original files unchanged. Work on copies. Save the exact instructions or a screenshot for your own records, but do not send private application information to an unrelated service.
Crop and resize images only as permitted. Keep identity details, stamps, dates and all required page edges visible. Follow the mission's photo rules rather than choosing dimensions from a different country's guide.
Combine pages only when the slot asks for one document. Keep unrelated categories separate and preserve page order. Don't remove transactions, pages or supporting evidence merely to hit a size target.
For an accepted PDF slot with a stated size limit, prepare a copy below that limit. If you use the free-to-process visa-application PDF compressor or BytesPDF Pro target-size compressor ($9.99/month; see pricing for checkout status), first confirm that the upload accepts PDF and that your mission allows a size-reduced PDF. Download the result instantly — the free compressor needs no account. Aim below the displayed cap to leave a margin for differences in decimal and binary MB.
Open the final copy and inspect it. Check names, passport numbers, account figures, dates, signatures and small print at normal and enlarged zoom. A PDF that meets the byte limit but is unreadable is not ready to submit.
Check the final file type and size in your device's file manager. Do this for every upload separately, then compare the name and contents with the intended portal field.

For bank statements, use the bank's original PDF download where possible rather than scanning printed pages. Keep all pages in date order, and don't remove transactions to reduce size. For image-heavy PDFs, resizing images before merging may reduce the file more effectively than repeatedly compressing the finished bundle.

Common reasons a file can fail even when it is small

Wrong extension: a PDF was uploaded to an image-only field, or a photo was put in a supporting-document slot.
Wrong application scope: a cap or format was copied from another mission, visa type or special event guide.
Unreadable detail: the passport number or machine-readable zone became soft after resizing or compression.
Missing pages: a statement or translated document was shortened to fit.
Unrequested bundle: unrelated evidence was combined even though the portal expects separate slots.
Photo mismatch: the image does not meet the mission's crop, background, orientation or pixel instructions.

When the portal rejects a file, use the exact error message to identify whether the problem is type, size, image quality, file protection or application completeness. A smaller file will not fix a format or eligibility issue.

Official source references

Thai e-Visa portal and English user manual — application workflow and portal instructions.
Thai government-hosted 2026 Annual Meetings e-Visa guidelines — event-specific file guidance; not a universal rule for all visa applications.
Royal Thai Embassy in Prague e-Visa instructions — mission-specific guidance; applicants elsewhere should use their own mission's instructions.

Before you upload

I checked the current upload field and the instructions for the mission handling my application.
The passport page, photograph and supporting evidence use the required formats for their individual fields.
Each file meets the size shown by that field; I have not treated a source-specific 3 MB figure as universal.
Related pages are combined only where the application asks for a single document.
Names, dates, passport details and financial evidence remain readable in the final copies.
The original files are preserved and no required evidence was removed to meet a size target.

Frequently asked questions

Is 3 MB the limit for every Thailand e-Visa upload?

No universal cap is established by the examples cited here. A 3 MB per-file maximum appears in specific guidance, including an event-participant document and mission instructions. Check the current field and the instructions for your application.

Must every Thai e-Visa passport page be a JPG?

Some cited mission or event guidance asks for the biodata page as JPG/JPEG. Don't apply that rule to every application without checking your own upload slot; follow the format listed in your application.

Can I upload a passport page as a PDF?

Only if the field for your application accepts PDF. If it explicitly requests JPG/JPEG, prepare an image copy and inspect the portrait, identity details and machine-readable zone before upload.

Should I compress every supporting PDF below 3 MB?

No. First check that the field accepts PDF and actually shows that cap. If it does, reduce a copy carefully, keep the original and inspect every page. If the slot requests an image or a different size, use those instructions instead.

Why can a file under the stated limit still be rejected?

It may use the wrong extension, be unreadable, omit a required page, violate photo instructions or belong in a different field. Use the portal's exact error and current checklist to diagnose the rejection.