There is one balance per account and everything draws it down. Understanding the two numbers below is most of what you need.
The hourly rate
Plans are advertised as a monthly price because that is how hosting is compared. The rate you are actually billed is derived from it over a 730 hour month:
hourly rate = monthly price / 730, rounded DOWN to 4 decimal places
Rounding down is deliberate. $3.50 / 730 is $0.004794…; rounded up that
would be $0.0048, which over 730 hours is $3.504, four tenths of a cent above
the price on the page. Small, but it is a published rate being exceeded, so the
derived rate is always floored.
730 is an average, not a calendar month
A calendar month is 672 hours in February and 744 hours in a 31 day month.
Hourly billing charges the hours that actually pass, so a server left running
for all of January costs 744 x rate, slightly more than the advertised
monthly figure, and February costs less.
Every cadence still meters hourly
Monthly and annual orders prepay account credit; they do not turn the server into a flat calendar-month subscription. See Prepaid months and years.
What meters hourly
- Servers. Every server that is not destroyed, including stopped and billing-suspended ones, because the CPU, RAM and disk stay reserved.
- Floating IPs, for as long as they are reserved, whether or not they are assigned to anything.
- Managed Services, per server it is enabled on.
What is charged some other way
- Bandwidth beyond the account pool, charged at the end of a period. See Bandwidth.
- Client API requests beyond the monthly allowance. See Rate limits and the monthly allowance.
Reading your own numbers
Billing opens on this month's statement: opening credit, credits added, usage line items, and the live closing balance. The current month is in progress and updates as hours are metered. Past months close on the last day.
The Statements tab is the list, one row per calendar month, labelled
STMT-YYYY-MM. Open any month, including the one you are in, for the
invoice-style document: issuer, bill-to, line items with quantity and rate,
and totals.
Receipts on the same page are deposits, not usage. A paid invoice is money that arrived; the statement is how that credit was spent.
Each server's Usage Graphs tab (/client/services/<id>/usage/) shows CPU,
memory, disk, network use, and its metered share of monthly transfer. Credit
charges for that server appear as a line on the monthly statement. If your
server has a custom quoted rate, the rate shown on its page is the rate that
applies.
The ledger is append-only
The balance is the sum of every ledger entry, not a stored number. Deposits, hourly debits, bonuses and staff adjustments are all rows. Nothing is ever edited or deleted, which is why the history always adds up to the balance you see.