One hundred kilobytes is often enough for a readable small photo when the canvas is sensible. The preset gives the encoder more room than the stricter limits, then validates the final output instead of estimating from the source file size.
Separate the pixel requirement from the byte requirement
A file can be under 100 KB and still be rejected because its dimensions are wrong. If the destination specifies both, enter both values. The result card shows the exact output pixels alongside the measured bytes so the two checks are easy to compare.
Questions people ask
Is 100 KB an official universal limit?
No. It is a convenience preset, not a promise about every form. Use the destination’s own instructions as the source of truth.
What happens when the output is below a minimum?
Set a minimum KB value as well as a maximum. The result is marked as needing attention if it falls outside that range.