Paid seats against seats in use: what the idle ones cost a year, and what you save by right-sizing at renewal.
Arithmetic only — not tax, accounting, legal or investment advice. Check against current rules.
Unused seat cost: Idle seats are paid seats minus seats in use, priced for a year. The right-sized count is active seats plus a buffer rounded up, and a lock-in period holds back the months in which seats cannot come off.
Quoted from the toolbelt spec, the document this tool was built against.
Negatives are parenthesized because that’s what a statement does. The rest is four promises.
Amounts are integers in the currency's smallest unit, end to end. A float never touches a cent.
Rounded once, at the end. Rounding each operand is how a split stops summing to the whole.
The arithmetic lives in one unit-tested module, and the extension uses the same one.
There is no request to make. What you type stays in this tab and is gone when you close it.
A calculator answers the question once. These carry the answer into a product, name what it computed, and argue the method.
Worked example. Type over it.
Result
“In use” is your call: last sign-in in the past 30 or 90 days from the vendor's admin report. A seat for someone on leave is not idle.