Is the size of sperm cells of mammals correlative to their size (E.g. is a blue whale sperm cell bigger than a human one)?

Sort of. For most animals up to about the size of humans have about the same size sperms. Over that size threshhold, the larger the animal the larger the sperm size and it increases exponentially.

Elephant sperms are visible to the naked eye in the right conditions.

Blue whale sperms kind of resemble a small loaf of bread, or more accurately like a soggy baguette.

Where did you get this information? All of the sources I can find don’t mention any sperm cells of any organism that are measured in units larger than microns.

No, it's somewhat unpredictable but there are some trends: https://www.cam.ac.uk/research/discussion/opinion-the-biggest-sperm-come-in-the-smallest-packages-and-other-odd-facts-about-male-sex-cells

To try and summarize that: There's a few different pressures. Larger sperm swim faster, so when one female tends to mate with more males within a short period of time, there's pressure towards both more and larger sperm. On the other hand, larger animals means larger reproductive tracts, so you increase the chance of finding the egg cell by having more sperm cells that cover the volume better, even if each of them are smaller and slower. The largest whales trend toward the "many, but smaller" side and have smaller sperm than humans.

From what I’ve heard there is actually an inverse correlation between sperm size and animal size. Some mouse had the largest where its tail in some cases could actually stretch to longer than the mouse itself. This sort of makes sense because a smaller volume ejaculated would necessitate a greater focus on quality over quantity.

What's the point of spreading blatant misinformation like that, do you gain anything from it ?

I found this article about sperm cells, and it's pretty counter intuitive. The largest mammalian sperm cell is from a mouse, the smallest from an elephant. Elephants make up for the difference by sheer volume produced, and they also have less competition; one bull elephant generally has a harem of cows, and does not need super energetic sperm. Male mice may have a lot of competition for a female, and need the speed.

The largest sperm cell in all animals is from a fruit fly. The are up to 5.8 cm long, up to 20 times longer than the fruit fly itself, and they only produce a handful at a time, all balled up on themselves. They cant swim like that, so they just kind of stuff them into the female.

I asked Duck about whale sperm; because google does not need to know about these kinds of searches, and it seems whale sperm is roughly the same size as human sperm. They don't have a lot of biological pressure for bigger faster sperm. I also found this wonderful article which i cannot tell if it is a parody or ai slop. While wildly wrong it is an amusing read.

Mice take the mating competition very seriously. Most of the fluid will form a gelatinous plug to prevent other males from fertilizing the eggs.

That was pretty funny. Especially if you calculate the total volume of 200 million 0.03 cm\^3 human male sperm heads (per the article) in a healthy young male’s ejaculate.

That is 600 liters and the liquid has not even been added yet

It's fascinating how counterintuitive scaling is across mammalians. For example, across all sizes of mammal from mouse to elephant, it takes roughly 21 seconds for a full urinary bladder to empty.