professional.utilisation
Billable utilisation and billing, collection and overall realisation rates, in basis points.
1.0.0 · published 2026-10-03 by charlie · Anterra
Pinned by 13 tests, run in TypeScript, Python and Rust.
What it does
The four ratios a professional-services firm (law, accountancy, consulting) reports for a fee earner, a team or the firm:
- **utilisation**: billable time over available time; - **billing realisation**: what was billed over the standard value of the time (the time at standard charge-out rates), so write-downs at billing show up; - **collection realisation**: what was collected over what was billed, so write-offs and bad debts show up; - **overall realisation**: collected over standard value, the product of the two.
For example
utilisation_rates(6,000, 8,000, £10,000.00, £9,000.00, £8,550.00)→ utilisation basis points 75%, billing realisation basis points 90%, collection realisation basis points 95%, overall realisation basis points 85.5% a typical quarter: 75% utilised, 90% billed, 95% collected, 85.5% overallutilisation_rates(1, 3, £3.00, £1.00, £1.00)→ utilisation basis points 33.33%, billing realisation basis points 33.33%, collection realisation basis points 100%, overall realisation basis points 33.33% a third rounds down to 3333 basis pointsutilisation_rates(2, 3, £0.03, £0.02, £0.02)→ utilisation basis points 66.67%, billing realisation basis points 66.67%, collection realisation basis points 100%, overall realisation basis points 66.67% two thirds rounds up to 6667 basis points
The function
The same function in TypeScript, Python and Rust, pinned by the same tests. Pick your language; the choice follows you around the registry.
def utilisation_rates(billable_minutes: int, available_minutes: int, standard_value: Money, billed_value: Money, collected_value: Money) -> UtilisationRates
| billable_minutes | int | chargeable time recorded in the period |
| available_minutes | int | contracted or target hours for the same period, in minutes; more than zero |
| standard_value | Money | the billable time at standard charge-out rates (the WIP value before write-offs) |
| billed_value | Money | what was invoiced for that time |
| collected_value | Money | what the client actually paid of the invoices |
| returns | UtilisationRates |
The type it declares, generated into your project
@dataclass(frozen=True)
class UtilisationRates:
"""Utilisation and the three realisation rates, in basis points of 100%."""
#: billable over available time
utilisation_basis_points: int
#: billed over standard value; null when standard value is zero
billing_realisation_basis_points: Optional[int]
#: collected over billed; null when nothing was billed
collection_realisation_basis_points: Optional[int]
#: collected over standard value; null when standard value is zero
overall_realisation_basis_points: Optional[int]
Your code names it in one line, in the file that uses it
from fune.professional.utilisation import utilisation_rates # professional.utilisation@^1
Imports name this capability’s declared dependencies, which fune builds next to it in your project; each one links to its page.
from typing import Optional
from .math_round_div import round_div ← from math.round-div ^1.0.0 · built alongside by fune
from .money_amount import Money ← from money.amount ^1.0.0 · built alongside by fune
from .professional_utilisation_types import UtilisationRates
def _ratio(numerator: int, denominator: int) -> Optional[int]:
# A ratio over nothing is not 0% or 100%: None says there was nothing to realise.
return None if denominator == 0 else round_div(numerator * 10000, denominator, "half-up")
def _check_minutes(name: str, value: int) -> None:
if isinstance(value, bool) or not isinstance(value, int) or value < 0:
raise ValueError("%s must be a non-negative integer, received %s" % (name, value))
def utilisation_rates(
billable_minutes: int,
available_minutes: int,
standard_value: Money,
billed_value: Money,
collected_value: Money,
) -> UtilisationRates:
"""Utilisation and billing, collection and overall realisation, in basis points."""
_check_minutes("billableMinutes", billable_minutes)
_check_minutes("availableMinutes", available_minutes)
if available_minutes == 0:
raise ValueError("availableMinutes must be greater than zero")
for name, amount in (("standardValue", standard_value), ("billedValue", billed_value), ("collectedValue", collected_value)):
if amount.currency != standard_value.currency:
raise ValueError("currency mismatch: %s and %s" % (standard_value.currency, amount.currency))
if amount.minor < 0:
raise ValueError("%s must not be negative, received %s" % (name, amount.minor))
return UtilisationRates(
utilisation_basis_points=round_div(billable_minutes * 10000, available_minutes, "half-up"),
billing_realisation_basis_points=_ratio(billed_value.minor, standard_value.minor),
collection_realisation_basis_points=_ratio(collected_value.minor, billed_value.minor),
overall_realisation_basis_points=_ratio(collected_value.minor, standard_value.minor),
)Install
fune build
With that line in your source, in a Python project (language python in fune.project), fune build resolves it and its 2 dependencies, pins them in fune.lock, downloads only the Python package of each, and builds the code above into your project’s .fune/build, one readable file per capability with a header linking back here. Or pin a range in fune.project and build in one step:
fune add professional.utilisation
The manifest, vectors and README with only the Python implementation. Install it without the registry with fune add ./professional.utilisation-1.0.0-python.fune, or fetch it from a terminal with fune pull professional.utilisation@1.0.0:python.
The whole function, every language, is one file too: professional.utilisation-1.0.0.fune, 17,094 bytes, sha256 f32bb3b6126fc9e69b155a7c56e388128aef8acae763806758ee20bb1b94c333. It installs into a project of any language.
Customise it in your app
The seams this capability offers. Put a marker directly above a function of your own and fune build wires it into the built code; the package on the registry is not changed, the built file’s header lists it under CUSTOMISED, and fune hooks lists every hook in the project. How hooks work.
before — your function gets the arguments and returns them, changed or not, or throws to refuse the call.
# fune: before professional.utilisation
after — your function gets the result and the arguments, and returns the final result.
# fune: after professional.utilisation
replace — inside this capability’s code only, calls to a dependency go to your function, with the same signature. Other capabilities that use it are unaffected; write in * to replace it everywhere.
# fune: replace math.round-div in professional.utilisation
# fune: replace money.amount in professional.utilisation
step — your function runs at a numbered point inside the function’s body, receives the in-scope values it names as parameters, and may return replacements. List the points with fune show professional.utilisation --steps.
# fune: step professional.utilisation after <n|label>
Tests
A version published now needs at least 8 tests for every function, and one that expects the error for each function that throws; the registry refuses it otherwise. fune verify --all runs each case in TypeScript, Python and Rust, and a project runs them again with fune verify. This page lists the cases; it does not run them. The exact JSON is vectors.json.
| Case | Arguments | Expected | |
|---|---|---|---|
| a typical quarter: 75% utilised, 90% billed, 95% collected, 85.5% overall | 6,000, 8,000, £10,000.00, £9,000.00, £8,550.00 | → | utilisation basis points 75%, billing realisation basis points 90%, collection realisation basis points 95%, overall realisation basis points 85.5% |
| a third rounds down to 3333 basis points | 1, 3, £3.00, £1.00, £1.00 | → | utilisation basis points 33.33%, billing realisation basis points 33.33%, collection realisation basis points 100%, overall realisation basis points 33.33% |
| two thirds rounds up to 6667 basis points | 2, 3, £0.03, £0.02, £0.02 | → | utilisation basis points 66.67%, billing realisation basis points 66.67%, collection realisation basis points 100%, overall realisation basis points 66.67% |
| exactly half a basis point rounds up, where truncating gives 0 | 1, 20,000, £200.00, £0.01, £0.01 | → | utilisation basis points 0.01%, billing realisation basis points 0.01%, collection realisation basis points 100%, overall realisation basis points 0.01% |
| time beyond contracted hours and premium billing both exceed 100% | 9,000, 8,000, £10,000.00, £11,000.00, £11,000.00 | → | utilisation basis points 112.5%, billing realisation basis points 110%, collection realisation basis points 100%, overall realisation basis points 110% |
| no billable time is 0% utilisation | 0, 7,500, £0.00, £0.00, £0.00 | → | utilisation basis points 0%, billing realisation basis points —, collection realisation basis points —, overall realisation basis points — |
| nothing billed: collection realisation is null, not 0% | 600, 1,000, £500.00, £0.00, £0.00 | → | utilisation basis points 60%, billing realisation basis points 0%, collection realisation basis points —, overall realisation basis points 0% |
| no standard value: billing and overall realisation are null | 600, 1,000, £0.00, £50.00, £50.00 | → | utilisation basis points 60%, billing realisation basis points —, collection realisation basis points 100%, overall realisation basis points — |
| in euros, part collected | 4,200, 6,000, €2,500.00, €2,000.00, €1,500.00 | → | utilisation basis points 70%, billing realisation basis points 80%, collection realisation basis points 75%, overall realisation basis points 60% |
| no available time is an error | 0, 0, £0.00, £0.00, £0.00 | → | error: availableMinutes must be greater than zero |
Show the other 3 tests
| Case | Arguments | Expected | |
|---|---|---|---|
| negative billable time is an error | -60, 1,000, £0.00, £0.00, £0.00 | → | error: billableMinutes must be a non-negative integer |
| mixed currencies are an error | 60, 1,000, £1.00, €1.00, £1.00 | → | error: currency mismatch |
| a negative collected amount is an error | 60, 1,000, £1.00, £1.00, -£0.01 | → | error: collectedValue must not be negative |
More from the author
All four come back in basis points (10000 = 100%), each rounded half-up to the nearest basis point from the exact integer ratio, once. None is capped: time recorded beyond contracted hours gives utilisation over 10000, and billing at a premium gives realisation over 10000; both are real and worth seeing.
A realisation whose denominator is zero is null rather than 0 or 100%: with no standard value there is nothing to realise, and reporting 0% would read as a total write-off. Available time of zero is an error instead, because a fee earner with no available time has no utilisation to report.
The three amounts must share one currency, and nothing may be negative; credit notes belong in the billed figure as a reduction, not as a negative period. How the firm defines "available" (contracted hours less holiday, or a target of chargeable hours) is the caller's choice; this only divides.
Files
| Path | Bytes |
|---|---|
| README.md | 1,450 |
| impl/python.py | 1,937 |
| impl/rust.rs | 2,787 |
| impl/typescript.ts | 1,931 |
| vectors.json | 5,100 |