Photo file size, without the guesswork

File size measures data; dimensions measure pixels

File size is the amount of data stored in an image, usually shown in bytes, KB or MB. Pixel dimensions are the width and height, such as 1600×1200 pixels. These describe different properties. There is no single KB value for a given width and height.

A textured scene needs more data than a plain background at similar JPG settings. Metadata and format also affect the total. That is why changing dimensions alone cannot promise a particular file size.

KB and KiB are not interchangeable

Toolmova uses an explicit unit selector. Decimal KB means 1,000 bytes, and MB means 1,000,000 bytes. Binary KiB means 1,024 bytes. A destination may use one of these conventions or display a rounded label. Check its stated requirement when possible.

A worked example: a file that looks like 100 KB

Imagine a JPG containing 100,352 bytes. It is below 100 KiB because 100,352 is less than 102,400. But it is above 100 decimal KB because it exceeds 100,000. A form enforcing the second limit can reject it even if a rounded display elsewhere appears to say 100 KB.

Use the actual output byte count to remove this ambiguity. A maximum also does not require an exact match: a 98,000-byte result is within a 100,000-byte cap, and adding filler data would serve no useful purpose.

Choose the operation that matches the requirement

• File too large, dimensions already correct: use compression first.
• Wrong pixel dimensions: resize with the aspect ratio preserved, unless distortion is intentional.
• Wrong shape or too much background: crop deliberately before checking size again.
• PNG input but JPG required: convert the format and choose a background for transparency.

Start with the highest useful limit

If your destination allows 500 KB, start there rather than forcing a 100 KB result. A larger budget can retain more detail, but preview quality is still a separate judgment. Use 500 KB, 200 KB or 100 KB according to the actual requirement.

Keep the original source. Repeatedly saving an already-compressed JPG can add visible artefacts. A compliant original JPG is returned unchanged by Toolmova's compression-only mode; this preserves its original metadata as well as its pixels.

What to do when a size target is impossible

Quality changes have limits. A high-resolution, detailed image may not fit an extremely small cap without changing its dimensions or losing unacceptable detail. Toolmova reports that situation instead of presenting an oversized result as compliant.

Raise the cap if allowed, remove unnecessary background with a deliberate crop, or permit a smaller image only when the destination allows the resulting dimensions. Do not trade away required text or document details simply to make a number smaller.

A final upload checklist

• Confirm the downloaded file is in the required format; renaming an extension is not conversion.
• Compare exact bytes with the destination's maximum.
• Check width, height, ratio and any minimum dimensions separately.
• Open the actual downloaded image and inspect faces, text and edges.
• Keep the original and follow the destination's current content and background rules.