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The calculator's own fields, action and results arrive with the verified pack when you load it. Nothing is computed in this page.
Deposit coverage · allocation arithmetic
Deposit-insurance allocation check
Check a deposit total against a per-institution coverage limit you supply: institutions needed for full coverage, and what an even split leaves exposed.
Verified engine
What the engine returns
Read the outputs against each other. The minimum-institutions figure says what full coverage would take in the best case; the shortfall figure says what the present even split leaves above the line at each institution. When the second is anything but nothing, the first is the size of the fix — and the distance between the two counts is how far the present arrangement stands from the smallest workable one.
Inputs the result is built from
Total deposits to insure
Number of separately insured institutions
Per-institution coverage limit
How the result is derived
MethodThe total divided by the limit and rounded up gives the minimum institution count; the total split evenly across the supplied count, less the limit and floored at zero, gives the per-institution shortfall.
StandardArithmetic allocation against a per-institution coverage limit
GuardA zero or negative total is refused — there is nothing to allocate and nothing to cover.
How the institution count moves with the total on deposit
What one limit per institution means for a growing total
The check is deliberately plain arithmetic on three numbers: a deposit total, a count of institutions treated as separately insured, and a per-institution limit typed in by the reader. It embeds no scheme’s rulebook, no country’s table and no current figure — the line it tests against is exactly the one supplied, which is what keeps a signed calculator from quietly impersonating a regulator.
The two outputs are two different readings of the same line. The minimum-institutions figure divides the total by the limit and rounds up: the smallest count under which full coverage is arithmetically possible at all. The shortfall figure takes the count actually supplied, splits the total evenly, and reports how far each equal slice sits above the limit — with nothing exposed reported as exactly that, rather than as a rounding accident.
Even splitting is the assumption doing the most work. Real balances are lumpy — a matured certificate here, a current account there — and an uneven spread can leave one institution exposed while the average looks fine. What the check describes is the best-behaved arrangement of the count it was given; matching reality to that arrangement is the reader’s side of the bargain, and no output here claims it has happened.
Coverage in the world is richer than one number per institution: schemes recognise ownership categories, joint holdings and temporary balances differently, and their aggregation rules decide what “separately insured” even means. None of that is modelled, and the page does not read any scheme’s terms. The arithmetic sizes the problem; what protection actually applies is for the governing scheme’s own published rules to say.
The total divided by the limit and rounded up gives the minimum institution count; the total split evenly across the supplied count, less the limit and floored at zero, gives the per-institution shortfall.
When this calculation is used
- Checking whether a matured certificate or an accumulating balance still fits under a per-institution line.
- Sizing how many separately insured institutions a lump sum would need for every part of it to sit within the limit.
- Seeing how much an even split leaves above the line at the count of institutions currently in use.
- Re-running the same total against a different limit, when a scheme publishes a new figure or when two schemes are being read side by side.
- Putting a number on a vague unease — turning “that account has grown rather large” into a count of institutions and an exposed amount per slice.
Worked example
A total in the middle six figures sitting across two institutions, tested against a typical published per-institution limit — the shape of the check after a windfall, a property completion or a matured certificate lands in one place.
Read the outputs against each other. The minimum-institutions figure says what full coverage would take in the best case; the shortfall figure says what the present even split leaves above the line at each institution. When the second is anything but nothing, the first is the size of the fix — and the distance between the two counts is how far the present arrangement stands from the smallest workable one.
Raise the institution count by one and re-run: the shortfall collapses to nothing the moment the even slice drops under the limit — and the minimum-institutions output had named that count before the experiment. Where actual balances sit is still a decision for the account holder; the arithmetic only reports whether a fit exists.
What each input represents
Total deposits to insure
The full amount whose coverage is being examined, across every account intended for the split. Interest keeps arriving after the check is run, so a total tested at the line today is past it later — the input worth revisiting on a schedule rather than once. Rounding it upward before entering costs nothing and biases the check in the safer direction.
Number of separately insured institutions
How many institutions — or ownership categories a scheme genuinely treats as separately insured — the total is spread across. Branches of one institution are typically one institution, and two brands can sit on one banking licence; whether two entities are separately insured is a fact about the scheme, and this input records the reader’s answer to that question rather than establishing it. When in doubt, the honest move is to run the check at the smaller count and see what the pessimistic reading says.
Per-institution coverage limit
The line to test against, supplied rather than looked up. Schemes differ between countries and their figures change; the pack ships an illustrative default, and the number that governs is whatever the scheme in question currently publishes.
Assumptions and limits
- The total is split evenly across the institutions counted; real, uneven balances can be exposed even when the even split is not.
- The limit is a single number applied per institution — scheme-specific aggregation, ownership-category and joint-holding rules are not modelled.
- The institutions counted are genuinely separately insured under the governing scheme, which is a fact this check cannot verify.
- The limit entered is current only because the reader entered it; schemes revise their figures.
- Balances are static for the check: interest arriving after it runs is not included.
What the guards protect against
- A zero or negative total is refused — there is nothing to allocate and nothing to cover.
- A non-positive institution count is refused: a split across no institutions has no meaning.
- A zero or negative coverage limit is refused — with no line to test against, both outputs would be undefined rather than reassuring.
Provenance
Arithmetic allocation against a per-institution coverage limit
The total divided by the limit and rounded up gives the minimum institution count; the total split evenly across the supplied count, less the limit and floored at zero, gives the per-institution shortfall.
Educational reference, not investment advice, and not a statement of any scheme’s rules — the coverage limit is an input. The signed pack carries its own citation; the page reports the verification state of the release it mounted rather than asserting one.