As Billy Kerr wrote, Hex is not a colour space, but a numerical system such as the decimal system, but with base 16.
The differences you notice are probably caused by different RGB colour spaces (such as sRGB vs. AdobeRGB), i. e. the RGB numbers from your graphic designer describe another colour than the mentioned online tool.
I will only complement the other answers.
RGB to HEX will give you the same exact color.
RGBA to HEX, will not because we do not even know what is beneath the color. If you put another color the overall color will change... that is the whole point of transparency.
So you have three options.
Convert the RGB values to HEX (without the alpha value) and add ...
No. There is no loss converting decimal RGB or RGBa colours to hexadecimal.
Forget online converters
In RGBa images, colours require 4 decimal or hexadecimal numbers, one for each channel. Each should be an integer from 0 to 255 (or 00 to FF). The alpha channel, like the other channels, should really be an integer between 0 and 255, and not a decimal ...
There is no such thing as HEX color. Its just a indication that the numbers are stored in hexadecimal. Which is a nifty way of keeping databytes aligned with the underlying computer memory,and thus always use the same width.
There is no conversion from 8 bit per channel color so there is no data loss. For any other bit depth loss is the same as changing to ...
RGBA to hex and backwards conversions have no losses except rounding errors, if the numbers are scaled. See for example Inkscape's coloring dialog (to use it you must have a dummy shape to be colored, I drew a rectangle):
Inkscape has scale 0...255 for R, G , B and Alpha. I had R=128, G=129, B=130, A=131. The hex version of those RGBA numbers is 80818283 as ...
Depends, you have to understand that there is no single RGB space and a single CMYK space. Those are just nomenclatures of how the colors are mixed not how big those spaces are.
So out of the three commonly defined RGB spaces sRGB, Adobe RGB and ProPhoto RGB the situation is really different. sRGB is meant to be standard but in a time when people used ...
6, 8, 10, 12-color process.
CMYK is referred to as 4-color process. So simply change the 4 to how many ever colors you are running. Of course, the natural follow up question is going to be "what are the [ additional ] colors?" So, you should be prepared :)
If these were spot colors, then it would still be referred to as a 6-color job.. but not "process". ...
On why? I can not tell without knowing the project. But most likely it is a matter of color profiles as almost always is the case.
There are two things you can do.
Send your file as RGB, which on digital printers often provide more saturated colors.
But most important. Print a color atlas on the exact same printer you are using and choose the color from ...
This is WAY late, but a simple workaround (for Mac users) is to open the PNG in Preview, then Export it as a PNG switching the default 16-bit option to the 8-bit option. It doesn't require any additional software, and only takes a few seconds.
At https://en.wikipedia.org/wiki/Tertiary_color#Tertiary-_and_quaternary-color_terms there's a column named "Quaternary CMY" that lists 24 hue names.
What no one seems to list however is names for values and saturations. A hue name combined with a value+saturation name gives the full HSV information and allows the color to be decoded.