Day count & proration
30/360 is wrong about the calendar and right about the contract. Both are here.
- Runs
- In this tab
- Data sent
- None
- Rounding
- Once, at the end
- Also in
- The Chrome extension
Day count & proration, worked
Showing a worked example — type over it
Result
How the day count & proration works.
Fiscal period resolver (any FY start), payment-terms calculator (Net 30, 2/10 net 30 and 2/10, n/30, EOM and Net 10 EOM, 15 MFI) with the discount decision, day-count conventions (actual/365, actual/360, 30/360, and ISDA actual/actual — the period split at each 1 January, leap-year days over 366 and the rest over 365), business-day arithmetic, and the day count that makes a proration exact.
Quoted from the toolbelt spec, the document this tool was built against.
Where these numbers come from.
Negatives are parenthesised because that is what a statement does. The rest is four promises.
Minor units, never floats
Amounts are integers in the currency's smallest unit, end to end. A float never touches a cent.
Rounded once
Rounded once, at the end — never per operand, which is how a split stops summing to the whole.
Unit tested
The arithmetic lives in one unit-tested module, shared without reimplementation with the extension.
No network
There is no request to make. What you type stays in this tab and is gone when you close it.
More in dates & terms
Read it in context
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The same number, elsewhere.
A calculator answers the question once. These carry the answer into a product, name what it computed, and argue the method.
- ComponentScheduleTableOne shell, seven presets. Prepaids through debt.
- ComponentPeriodPickerFiscal-aware. Never assumes January.
- ComponentCutoffWarningInline, with both legitimate remedies named.
- TermAccrualAn expense incurred, or revenue earned, before it is invoiced — recorded at period end so it lands in the right period
- TermDeferralCash paid or received ahead of the expense or revenue it relates to, held on the balance sheet — as a prepaid or deferred revenue — until consumed or earned
- TermPeriodA fiscal reporting window
- DocSchedules, accruals & roll-forwardsThe supporting evidence layer. Every balance sheet account needs a schedule behind it, and the schedule must tie.
- DocPeriods & the closeThe month-end close in accounting software: fiscal calendars, period states, cutoff, reconciliation vs tie-out, adjusting entries and restatement.
- EntryJournal entry for accrued wagesAt month-end, debit Wages and salaries and credit Accrued wages for the days worked since the last payday. On payday, reverse the accrual or debit Accrued wages for the part of the payroll it covers.
- EntryJournal entry for accrued interestAt month-end, debit Interest expense and credit Accrued interest for the interest earned by the lender since the last payment. When the payment is made, debit Accrued interest and credit Cash.
- DocCurrency decimal placesHow many decimals each ISO 4217 code is stored at — JPY 0, USD 2, KWD 3.