About us

Pixels to Inches exists because “how big will this print?” has a precise answer, and most tools that claim to give it hide the one number the answer depends on: the pixel density.

What this site is

This is a tool, not a publication. There is no editorial team behind it and no company narrative to tell, so this page is written about the instrument rather than about anyone's biography — a founder story would tell you nothing about whether the numbers are right. What follows is the part you can actually verify.

What it does: four calculators sharing a single DPI control — pixels to inches, inches to pixels, image dimensions to print size, and a screen PPI finder that derives a real display's density from its resolution and diagonal. Around them sit 14 focused converters and calculators, 12 plain-language guides and reference tables for the times you need to check a number rather than compute one.

Why you can check the answer yourself

A pixel conversion is arithmetic, not judgement. There is no model, no heuristic and nothing proprietary inside this site — which means you never have to take a result on faith. Every page states the formula it used and fills it in with the values you entered:

inches = pixels ÷ PPI
pixels = inches × PPI
PPI    = √(width² + height²) ÷ diagonal

That worked line is not decoration. It is rendered from the same state the result panel reads, so it cannot show one calculation while the answer comes from another. If a figure ever looks wrong, you can do the division on a calculator and see immediately whether the site or your expectation is at fault. That is the whole basis on which this site asks to be trusted: not authority, but a visible working.

Where the constants come from

The only place a converter can quietly go wrong is in the constants it starts from. Here are the ones this site uses and the standard each is taken from.

• 1 inch = 96 CSS pixels W3C CSS Values and Units The reference pixel the web platform is defined against. It is a unit of the specification, not a measurement of your monitor.
• 1 inch = 25.4 mm International yard and pound agreement, 1959 Exact by definition, not rounded. Every millimetre figure on this site is derived from it.
• 1 inch = 72 points PostScript / DTP point The point used by design software and CSS. The older Didot and American points are different sizes and are not used here.
• 1 inch = 6 picas Same PostScript basis 12 points to the pica, 6 picas to the inch.
• A4 = 210 × 297 mm ISO 216 ISO paper is defined in millimetres. The inch figures shown for A-series sizes are converted from those millimetres, never the other way round.
• US Letter = 8.5 × 11 in ANSI/ASME Y14.1 North American sizes are defined in inches, so those are the authoritative numbers and the millimetres are derived.

Things this site refuses to do

• It will not hide the density. A pixel count has no physical size until you name a PPI, so the DPI control is always visible and always part of the stated answer. A tool that converts pixels to inches without asking you for a density has picked one for you and not told you which.
• It will not round silently. Results are shown to enough decimal places to be checked. Where a figure is exact by definition — 25.4, 72, 96 — it is used exactly.
• It will not give a print-quality verdict as a single threshold. Sharpness depends on viewing distance, so quality is reported as a range. A billboard at 30 DPI is fine; a business card at 150 DPI is not.
• It will not present a marketing figure as a measurement. Screen densities are computed from resolution and diagonal with the formula above, not copied from a spec sheet.

How mistakes get handled

They do happen, and the useful question is what happens next. Three things are already in place:

• Every page derives its own copy from its own numbers. The prose on a size page is generated from that page's measurements rather than written by hand, so a sentence cannot describe one conversion while the table below shows another.
• Contradictions are refused at build time, not published. The page generator compares each page's slug against the conversion it performs and fails the build rather than shipping a page whose URL disagrees with its content. Six pages were caught this way and corrected.
• Corrections are recorded, not quietly applied. Renames, removals and reassignments live in a checked-in override file with a reason attached, so a change can be traced back later instead of vanishing into the history.

Where a source measurement is implausible — a size that is almost certainly a typo rather than a real request — the page says so in a note instead of presenting the nonsense number confidently.

Privacy is a property of the design

Every calculation runs in your browser. Nothing you type is transmitted: there is no analytics script, no advertising, no account and no server that ever sees your dimensions. The image you drop into the DPI checker is read locally and never uploaded. This is not a policy promise layered on top — it is what the code does, and the privacy page sets out exactly what was checked to confirm it.

Corrections welcome

If a value looks wrong, say so and it will be checked against the standard and fixed. That is the fastest route to improving the site, and it is taken seriously. Write to hello@pixelstoinches.com or use the contact page, which explains what to include so a report can be reproduced.