What each one does
Kilograms and pounds
Type into either field and the other fills in as you type, to two decimal places. It uses the factor 2.20462, which is the exact definition (one pound is 0.45359237 kilograms) shortened to six digits. Those two units are all it handles: there is no grams, ounces, stones or tonnes option, so a body weight quoted in stones and pounds needs converting to pounds by hand first. For a weight that will be used in trade, customs or medical dosing, take the figure and the rounding rule from the calibrated instrument instead.
Time zones and world clocks
Give a city, a date and a clock time, and it returns the matching local time in a second city, with the destination's calendar date alongside. Daylight saving for the date you chose is applied from your browser's own time-zone data rather than a fixed offset table, so a date inside a clock-change window is handled correctly. The limit is coverage: twenty cities, with no search across the full time-zone database and no way to add one. It also will not create a calendar entry, so for a recurring meeting use a calendar application that stores the zone with the event.
Image formats and file size
Add one or more pictures and re-encode them: a quality setting, a maximum width or height, an output format of JPG, PNG or WebP, and an optional target size in kilobytes that it attempts and then reports on. Everything is written from decoded pixels, which is why animation, EXIF data and colour profiles do not survive the trip and why a PNG with transparency loses it when written as a JPG. It is not an editor: for cropping, rotating, retouching or text on an image, use an image editor and bring the result back here to shrink.
DOCX text to PDF
This one extracts the words from a .docx file and writes them into a PDF as plain 12-point text. That is the whole of it: formatting, bullets, table structure, images, headers and footnotes are not carried over, and text outside the Western Latin range stops the conversion rather than producing gaps. Whenever the document's appearance matters, use the Save as PDF or Export as PDF command in Word, LibreOffice Writer, Google Docs or Pages, which renders the real pages.
Choosing between them
Start from the output you actually need. If you need a number to read or quote, the weight and time tools give you one directly. If you need a file to send, the image and document tools give you a new file and leave the original untouched — so keep that original until you have opened the result and checked it.
A converter is also the wrong tool in some common cases. It cannot make a measurement more accurate, it cannot recover detail that a previous compression threw away, and it cannot rebuild a layout from text. When any of those is what you were hoping for, the fix lies with the source: a better instrument, the original image file, or the application that created the document.
Exact conversions and rounded ones
Some conversions are exact by definition. A pound is defined as 0.45359237 kilograms, an inch as 25.4 millimetres; the relationship is fixed by agreement, not measured, and the only error comes from how many digits you keep. A tool that shows two decimal places is rounding a known value, so the answer is reliable to about a hundredth of a unit and no further.
Other conversions are not exact at all. A time-zone offset is a political decision that governments change, and image compression discards information. In those cases the figure is correct only for the rules or the file in front of you.
Two habits cover both situations. Carry extra digits while a number is still being calculated and round once at the end, rather than rounding at every step. And when a converted figure matters — a shipping band, a flight time, a submission deadline — confirm it against the organisation that will act on it.
Reviewed October 1, 2026. Calculation methods and corrections