Service Charge Split Calculator
Shares a building's bill between its lots in proportion to their shares, with the column adding up to the bill exactly.
Shared out
12,480.50
- Lots
- 5
- Shares in total
- 1,000.00
- Lots given a spare cent
- 2
Each lot
| Lot | Shares | Share of the bill | Exact | Charged |
|---|---|---|---|---|
| Flat 1 | 145 | 14.5 % | 1,809.6725 | 1,809.67 |
| Flat 2 | 210 | 21 % | 2,620.905 | 2,620.91 +1c |
| Flat 3 | 325 | 32.5 % | 4,056.1625 | 4,056.16 |
| Flat 4 | 187 | 18.7 % | 2,333.8535 | 2,333.85 |
| Shop | 133 | 13.3 % | 1,659.9065 | 1,659.91 +1c |
The marked lots carry one extra cent each, so the column adds up to the bill exactly.
Sharing a bill in proportion to a set of shares is a multiplication. Making the column add up to the bill is not: exact shares almost never land on whole cents, and rounding each one on its own leaves the total a few cents out.
That difference has to go somewhere, and in most spreadsheets it goes to whoever is typing. Here it is dealt with by construction.
How it works
Each lot's exact share is the amount times its shares over the total of all the shares. The shares can be thousandths, square metres or anything else: only their proportions matter, so they do not have to add up to a round number.
The split is then done in whole cents. Every lot gets its whole cents, which leaves a handful over — never more than one per lot less one. Those go one each to the lots whose exact share had the largest fraction of a cent left on it.
The result is a column that adds up to the bill exactly, where no lot is more than a cent away from its exact share. The lots that received a spare cent are marked, so the adjustment is visible rather than absorbed.
Examples
| Case | Input | Result |
|---|---|---|
| A yearly budget across five lots | 12,480.50 shared over shares of 145, 210, 325, 187 and 133 | 1,809.67, 2,620.91, 4,056.16, 2,333.85 and 1,659.91. Two of them carry a spare cent, and the column adds up to 12,480.50 exactly. |
| A bill that does not divide | 100 shared equally between three lots | 33.34, 33.33 and 33.33. The spare cent goes somewhere, and the page says where. |
Frequently asked questions
Do the shares have to add up to 1,000?
No. Only the proportions matter, so any set of numbers works — thousandths, ten-thousandths, floor area, or a count of radiators. A total of 1,000 is a common convention, not a requirement.
Who gets the spare cent?
The lots whose exact share had the largest fraction of a cent left over, one cent each until the column adds up. Where two are tied, the one listed first gets it — which is arbitrary, and is said to be arbitrary rather than dressed up as a rule.
Is this how my building has to do it?
Not necessarily. Some rules round every lot down and leave the remainder with the building; some charge different lots on different bases entirely — a lift bill that the ground floor does not share in. This applies one basis to one amount, which is what makes it worth running once per category of charge rather than once per year.
Good to know
- Amounts carry no currency: the answer is in whatever you put in.
- Results use double precision floating point arithmetic. That is exact enough to decide with and is not an accounting record.
- The list travels in the address of the page, which is what makes a result shareable and bookmarkable — and is also why it is not the place for anything you would not put in a link. Nothing is stored.
- One basis of apportionment at a time. A building whose charges split several ways needs the tool run once per basis, which is also how the accounts themselves are usually drawn up.