Question about Brother Tn-241

Unfortunately, I have to tell you that the number varies greatly. This may be ok for private use but unfortunately not useful in the office. mfg cisco

I correct myself, that's why it's between 01.09.14 and 26.08.15. I just checked.

I'm sorry to say that I don't count the sheets. What I can tell you is that I print two pages (B/W and colour) every day and the levels are now half full. The period is between 26.08.15 and about 01.03.15, about 6 months.
For a small business, and a household it is well enough without having to complain. The figures are always a median value, and you don't always need the same amount of toner when printing.
I use it to print invoices, quotations, envelopes, the occasional googlemap or small brochures.