Am I missing something?

This is just curiosity..
Quoted daily 'in-world' transactions in $US (is that what it is?) on the SL home page sort of run-out at about US$300,000/day.

But this doesnt quite taslly with figures quoted of 'in-world' transaction of around L$90M per month at
https://secondlife.com/currency/economy.php
for July...

I'm not seeing where you're seeing a number of $L90 million per month?

The only numbers that I see that relate to transactions are the actual number of transactions but those don't specify a Linden amount, just the number of transactions and the range in price those transactions were in.

Even taking just this number and using the lowest price in the range:

100,000 - 499,999 L$ - 1,131

we get a total of 113,100,000 which is more than the 90 million you were stating.

Also, take into account that number on the homepage also includes the Lindex if I'm not mistaken which account for roughly $45,000US a day.

Thanks Maximillion,

I was using the the sink and source totals as a combined number (naively) which of course doesnt represent transactions - as becomes clear with your example.

So extrapolated is my math right to rough out
$300,000 US/day = (at say 305L$/US$) = L$91.5M/day
therefore monthly
(x30 say) US$9M/month = (at say 305L$/US$) = L$2745M/month

if, as you say, the Lindex is in the homepage numbers then it doesn't quite represent 'spent in world' then as people can buy L$ today on Lindex but not spend them 'in-world' - but strictly speaking I guess it is US$ spent..

Is there somewhere that gives a good overview of this type of stuff? e.g. information for the unitiated? And specifically what the number on the homepage includes?

Ah yes, the souces and sinks just shows new money coming into the economy and money that has left the economy permanently through stuff like texture uploads.

Go through the posts by Lawrence Linden and Robin Linden. I can't remember which but one of them did clarify the number on the homepage at one point. Lawrence would be a good place to start.