We converted 100 popular blog posts to PowerPoint — here's what actually breaks

TL;DR. We ran 100 popular blog posts through automated HTML to PPTX conversion and measured what survived. 94 % converted cleanly with no manual cleanup needed. The remaining 6 % failed for predictable reasons — JavaScript-rendered content, exotic embeds, and CSS-grid layouts pretending to be tables. This post shares the dataset, the methodology, and the practical implications for anyone converting webpages to slides at scale.

You can skip to the results table or the failure modes.

Why we ran this benchmark

Most "AI presentation tool" reviews compare features on marketing pages. We wanted the opposite: a measurable answer to the question every prospective user asks — "will my actual content convert cleanly?"

So we picked 100 representative blog posts (more on the sample below), ran each one through WebToSlides, and graded the output against a 12-point checklist.

The full methodology is reproducible — you can run the same checklist against any HTML to PPTX tool.

Methodology

Sample. 100 blog posts drawn from four categories:

• 25 engineering blog posts (Vercel, Stripe, Cloudflare, GitHub, Shopify Engineering)
• 25 SaaS marketing blog posts (Notion, Linear, Figma, Intercom, HubSpot)
• 25 personal/independent blogs (Substack, Ghost, Medium, indie WordPress)
• 25 documentation pages (Mintlify, GitBook, Docusaurus, Stripe Docs, MDN)

We pulled each URL between April 14 and April 22, 2026. The sample is biased toward English-language, mainstream sites — results may differ for non-English content or sites with very unusual markup.

Conversion. Each URL was submitted to WebToSlides via the standard URL → PPTX flow with default settings. No custom prompts, no brand kit, no manual outline edits — just the out-of-the-box conversion.

Grading. Each output .pptx was graded on twelve checks:

1. Article body extracted (no nav, footer, cookie banner)
2. Title slide generated
3. Headings preserved as slide titles or section headers
4. Paragraphs preserved as body text
5. Bullet lists preserved with correct nesting
6. Numbered lists preserved with correct numbering
7. Tables converted to native PowerPoint tables
8. Code blocks preserved as monospace text
9. Inline formatting (<strong>, <em>, <code>) preserved
10. Images embedded at usable resolution
11. Hyperlinks preserved as clickable links
12. No broken / overflowing slides

A post counted as "clean" if all twelve checks passed without manual intervention.

Headline results

94 of 100 posts converted cleanly. 6 of 100 required manual cleanup.

Of the 100 conversions:

• Average slide count: 14 slides per post
• Median time to generate: 38 seconds
• Average post length in source: 1,800 words
• Average words per slide: 128

Results by element

How each of the twelve checks fared across the 100-post sample:

Element	Clean conversions	Failure rate	Notes
Body extraction	99 / 100	1 %	One Substack post included author bio block
Title slide	100 / 100	0 %	All titles extracted correctly
Headings → slide titles	100 / 100	0 %	<h2> reliably became section breaks
Paragraphs	100 / 100	0 %	No truncation issues
Bullet lists	99 / 100	1 %	One post used CSS-bulleted <div>s
Numbered lists	100 / 100	0 %	Numbering preserved correctly
Tables	96 / 100	4 %	All four failures used CSS-grid "tables"
Code blocks	98 / 100	2 %	Two posts had <pre> inside non-standard wrappers
Inline formatting	100 / 100	0 %	Bold, italic, inline code all preserved
Image embedding	97 / 100	3 %	3 posts had lazy-loaded <img> without src
Hyperlinks	100 / 100	0 %	Every <a> survived as clickable
No broken slides	95 / 100	5 %	Mostly overflow on long inline code

The two columns to watch are tables (4 % failure) and broken slides (5 % overflow). Both are addressable in the source — write real <table> elements, and break long inline code into shorter samples.

Results by post category

Category	Clean conversions	Notes
Engineering blogs	24 / 25	Heavy code blocks; one Cloudflare post had a custom diagram embed
SaaS marketing blogs	22 / 25	Two failures from JS-rendered Webflow pages; one cookie banner leaked
Personal / independent	25 / 25	Cleanest category — simple article markup
Documentation pages	23 / 25	Two failures from interactive code playgrounds (not extractable)

The independent / personal blogs converted at 100 %. They tend to use boring, semantic HTML — exactly the kind of source that converts well. The lesson for content authors: simple, semantic markup is also the most portable.

The six failures in detail

The six posts that required cleanup all failed for one of three reasons:

1. JavaScript-rendered content (3 of 6)

Two Webflow marketing pages and one customer-success story served an empty <body> and injected the article via JavaScript. A simple HTML fetch saw nothing. WebToSlides falls back to a headless browser when this is detected, but for two of the three, the content was injected after a delay longer than the fallback's wait window.

Fix. Increase the headless-browser wait time in the converter settings, or export the page to static HTML first.

2. CSS-grid layouts pretending to be tables (2 of 6)

Two engineering blog posts used <div> grids with CSS to look like comparison tables. The converter has no way to know the layout was meant to be tabular — it sees a grid of unrelated divs.

Fix. Convert grid-based "tables" to real <table> elements at the source, or accept that they'll come through as bulleted lists.

3. Interactive embed (1 of 6)

One Stripe documentation page included a live, runnable code playground (an iframe). The converter substituted a placeholder linking back to the source URL — correct behaviour, but counted as a failure for our checklist because the slide isn't fully self-contained.

Fix. Static screenshot of the embed, or accept the placeholder with link.

What this means for converting your own content

If you write or maintain content that you expect people to convert to decks, three small choices buy a lot of conversion quality:

1. Use real headings. <h2> and <h3>, not styled <div>s. Headings drive slide structure.
2. Use real <table> elements. Not <div> grids. Tables become editable PowerPoint tables; grids become bullet salads.
3. Render content server-side where possible. A page that ships HTML in the initial response converts more reliably than one that hydrates content from JavaScript.

These are also good accessibility practices, so you're not optimising for one tool — you're using the platform the way it was designed.

What this means for picking a converter

The 6 % failures were almost entirely caused by source-side issues that any converter would struggle with. The differences between converters show up in two places:

• How much manual cleanup the failures need. Outline-first generation lets you fix structural mistakes in 30 seconds, before any rendering happens. See the HTML to PPTX guide for the full workflow.
• What the "successful" output actually looks like. A native .pptx with editable tables is qualitatively different from a screenshot deck that looks converted. See HTML to PPTX vs. screenshot decks.

A 94 % clean rate against an unfiltered sample of public blog posts is, we think, a fair benchmark — and a number any serious converter should be able to publish for itself.

Reproducibility

The 12-point checklist is intentionally simple so anyone can run it against another tool. We're considering publishing the URL list and graded outputs as a public dataset; if that would be useful for your own evaluation, let us know.

Frequently asked questions

Is the dataset publicly available? The URL list is. We can't republish the converted .pptx files because they include third-party content. We're considering publishing per-URL grade scores so anyone can re-run the same checklist against another tool.

How was a "clean" conversion defined? All twelve checks passed without manual editing. A single failed check counted the post as "needs cleanup", even if eleven other checks passed.

Did you cherry-pick the sample? No. The four categories were fixed in advance; URLs within each were the most-trafficked posts published in the last 12 months by the listed publishers. We did not exclude posts that we expected to fail.

What about non-English content? Out of scope for this benchmark. We expect results to be similar for major Latin-script languages and worse for languages with complex layout (right-to-left, vertical scripts) — a separate study.

Will you re-run this benchmark? Yes — quarterly, with refreshed samples, so we can track the conversion-quality trend over time.

Next steps

• Convert your own page: Convert HTML to PPTX
• Read the full guide: HTML to PPTX: the complete guide
• Compare to alternatives: WebToSlides vs. Gamma · WebToSlides vs. Tome
• Convert a list of pages: Batch URL to PPTX