I have Mikrotik v5.7 with hotspot.

I have user profile with 400kbps download and 25kbps upload and another profile with 800jbps download and 50kbps upload.

Is it correct to put the rate limit(rx/tx) as 25k/400k for the first profile and 50k/800k for the second profile.

I am asking this because I read from some forum they put in the rate limit more speeds and they say this will make browsing faster.

Hi,
Simply, As you know every connection need both send and receive. If You limit the client (which have receive more than send) it will affect on the speed. for example , when you open google.com and write in search filed "Mikrotik", this word have to send to the server to reply to your search. So the send speed is also important.
If I were you, I set the profile limitation like this:
Instead 25k/400k ----->> 200k/400k ---->> send is half

Usually uses in ISPs.

Hi,
Simply, As you know every connection need both send and receive. If You limit the client (which have receive more than send) it will affect on the speed. for example , when you open google.com and write in search filed "Mikrotik", this word have to send to the server to reply to your search. So the send speed is also important.
If I were you, I set the profile limitation like this:
Instead 25k/400k ----->> 200k/400k ---->> send is half

Usually uses in ISPs.

let lets say that I have 12mbps download and 1Mbps upload and 30 active 400kbps download users. wouldn't 200kbps upload be too much for them. what do you suggest?

I think it's good to read some about Mikrotik Queue http://wiki.mikrotik.com/wiki/Manual:Queue
and Burst Capability http://wiki.mikrotik.com/wiki/Manual:Queues_-_Burst
when read these, you can make a better decision.
Another thing that you must know is most client have much receive than send and it happens rarely all user have full send at the same time.

Isn't better to use something like

rate limit: 25k/400k 100k/400k 50k/400k 10

As I said you can use burst. Read about burst in Wiki and you will see :
for example if you set max upload to 25k, burst threshold to 50k ,burst-limit to 100k and burst time to 8s,
the router will check every 8 seconds and check if the user reach the threshold, see if the bandwidth is free let him to reach to burst limit.

thank you sadeghrafie. I will try this