These sites are made for normalfags to share on facebook and feel amazed at how cool science is. They are next to useless except as rudimentary tools.
Time to crack, entropy, etc. is impossible to calculate just from the data itself. Here's a random string:
>KGJGZHVLNC
What's the entropy? Entropy is just the logarithm of all possibilities, so let's look at those.
If you assume that the rule is "uppercase letters" there are 26^10. But how do you know they were English letters? If the Czech alphabet was used, you get 42^10. How do you know they were all uppercase? What if I generated mixed case and just happened to get only upper case ones? What if my alphabet was in fact CGHJKLNZ? You won't see A in there, why do you assume it was a possibility?
In fact, what if my generation method was:
Pick random integer x s.t. 0>x>=1
if x==1 return KGJGZHVLNC
Then the entropy is 0.
You see now that entropy is entirely dependent on context. With passwords, the question is, what does the hacker think your password will be? If the hacker is a retard who tries every combination of every ASCII character, first for 1 char, then 2 chars, etc. Then aaaaaaaaaaaaaaaaaaaaaaaaaaa is an excellent password with superb entropy. If your password is "strop 17 aw tete karp", the entropy depends on what the hacker thinks. Does he expect that your password could be any string? Then he will have to try everything and entropy is high. Does he somehow expect that you will have a password made of words, then he can look for dictionary words delimited by spaces, and entropy is lower.
In reality, hackers don't sit around trying to guess what your password is. Every time news breaks out about x million compromised accounts, they obtain that list, add it to other lists they already have, and make a list of top X most common passwords. When hacking you (more like hacking millions of people at once which happen to also include you), they try the X most common passwords (or password patterns), and if none work for your account move on. A proper password strength checker would have such a list, and determine password strength according to that. These password strength checker sites are just useless toys that try to cash in on security hysteria.