The definition the association adopts, why the calculations in use diverge, and a calculator to check whether your figures add up.
Why this page exists
A definition of average length of stay exists, it is single and it is national. ABRAHCT adopts that one, and no other.
The formula is in Ordinance SAS/MS 312/2002 of the Brazilian Ministry of Health, in indicator sheet E-EFI-05 of the ANS QUALISS programme and in the ANAHP Observatory, and it is always the same: patient-days in the period divided by discharges. It is not a matter of choice or opinion.
What the association found, checking the responses to its latest survey, is that not every institution applies the standard. Cross-referencing beds, occupancy, admissions and length of stay within a single response, some of them do not add up, and the reason is known: other calculations circulate in the sector under the same name, such as measuring the length of stay of currently admitted patients, or dividing patient-days by admissions instead of discharges. Two of them are simply wrong, and this page shows why. Until they are all aligned, comparing two institutions measures the choice of formula rather than the care delivered.
Hence what you find here: the definition together with the operational rules the national standard does not spell out, such as what counts as a discharge and what an operational bed is; the four calculations in circulation, so you can identify which one you use today; and a calculator to check whether your own figures add up before any of them leaves your institution. Criticism of the methodology is welcome, and the address is at the foot of the page.
Before you calculate
Institutions in the sector usually run three lines at once, and the association's articles list them side by side: post-acute care, step-down care and palliative care. They have different goals, and length of stay only measures performance in one of them. Adding the three into a single figure produces an indicator that describes none of them.
Length of stay applies
Restore function and discharge the patient.
Length of stay does not apply
Sustain the complex chronic patient.
Length of stay does not apply
Comfort and quality of life.
What this means in practice: the calculator below asks which line the data comes from, and only measures length of stay as performance in the first one. Mixing a palliative care patient with rehabilitation patients in the same calculation produces a figure that cannot support any decision, and which, quoted out of context, reads as inefficiency. The indicators suggested for step-down and palliative care are a proposal by the association, still under discussion: unlike length of stay, no national specification standardises them.
Calculator
Without relying on anyone's word, including your own. Total patient-days for a month can be added up along two independent paths: from the capacity side, meaning how many beds you have, for how many days and at what occupancy; and from the movement side, meaning how many patients were discharged and how long each one stayed. Both paths describe the same reality, so both have to give the same number. This is not a convention, it is accounting.
operational beds × days in period × occupancy
= discharges in period × average length of stay
When the two sides do not give the same number, one of the four figures was measured with a different definition from the other three, and that is what the tool below points out. It works in two steps: paste the length of each completed admission and it returns your distribution, with median and percentiles, already filling in discharges and length of stay; complete it with beds, days and occupancy and it closes the calculation. The data stays in your browser: nothing is sent to the association.
Step 1, optional
One per line, or separated by comma, semicolon or space. Paste straight from a spreadsheet column. With this list, the discharges and length of stay fields in step 2 fill themselves in.
Step 2
Capacity for the period
Beds able to receive a patient in the period, not installed beds
30 for a month, 90 for a quarter, 365 for the year
Average for the period
Discharges, deaths and external transfers. Internal transfers do not count
Optional. Fill it in to check whether it matches the other figures
Do your figures add up?
Fill in beds, days, occupancy and discharges to close the calculation.
The data stays in your browser. Nothing is sent to ABRAHCT.
The definition
Average length of stay is the sum of patient-days in the period divided by the number of discharges in the same period, counting discharges, deaths and external transfers — the formula of the Brazilian Ministry of Health's Hospital Census Nomenclature Standard (Ordinance SAS/MS 312/2002), the same used by the ANS QUALISS E-EFI-05 indicator and by the ANAHP Observatory.
Scope. It is measured by line of care. As a performance indicator, length of stay applies to the post-acute care and rehabilitation line, which has a discharge goal from admission onwards. In step-down and palliative care it describes the service rather than assessing it, and it must not be added to the other lines nor published as efficiency.
The daily sum of patients admitted at 00:00, as the ANS indicator sheet requires. A patient admitted and discharged on the same day counts as one patient-day.
A transfer between beds or wards within the same institution is not a discharge and does not end the admission.
In the occupancy rate used for validation, the denominator excludes blocked beds and includes extra beds — beds genuinely able to receive a patient.
The duration of each completed admission (discharge minus admission; same day counts as 1) is the data behind the median, P25 and P75, always published alongside the mean.
The four calculations
These are the four that turned up in the responses to the association's survey. One is the standard, one is complementary and two are wrong, in the sense that they bias the result in a predictable direction. Before comparing your figure with any other institution's, identify which one you use today.
Divides total patient-days in the period by the number of discharges in the same period (discharges, deaths and external transfers).
It is the Brazilian national standard: Ministry of Health Ordinance SAS/MS 312/2002, the ANS QUALISS E-EFI-05 indicator sheet and the ANAHP Observatory all calculate it this way. It is the figure that can be compared across institutions and with the rest of the health system.
Takes the admissions that ended within the period and measures the full duration of each one: discharge date minus admission date.
This is where the median and the percentiles come from, which the mean does not reveal. In a stable unit, the cohort mean converges to the official indicator.
Measures how long the patients present on the census date have been admitted.
Always overestimates: a patient who stays 200 days appears in 200 daily censuses, one who stays 10 days appears in 10. The long-stay patient enters the calculation twenty times more often.
Uses admissions instead of discharges in the denominator.
The most common spreadsheet error. It understates in a growing unit and overstates in a shrinking one.
How to publish it
The distribution of length of stay in post-acute care is skewed to the right: a handful of very long stays pulls the mean away from the typical case. Two units with the same mean can have quite different clinical realities.
For that reason the association always publishes median, mean, 25th and 75th percentile together, with the number of completed admissions behind the statistic. The median is the typical case; the distance between it and the mean measures the skew; the percentiles show the range holding the middle half of cases.
Outside Brazil
There is an understandable fear in the sector: a high length of stay, published without context, would be read as inefficiency. International experience points the other way. In countries that created a classification of their own for the post-acute stage, a long stay is precisely what characterises the category.
LTCH, Long-Term Care Hospital
above 25 days
Not an observed average: it is the entry criterion. To be paid as an LTCH under Medicare, a hospital must have an average length of stay above 25 days. A long stay is what defines the category, not what disqualifies it.
Intermediate care
up to 6 weeks
The length of stay ceiling set out in NHS policy for rehabilitation and recovery services after hospital discharge. It is a programme parameter, not a measured average.
None of these figures can be compared with the length of stay practised in Brazil. They are categories with rules of their own, defined in another health system and with a different entry criterion. The OECD publishes average length of stay, but for acute care hospitals, which is a different thing: comparing would be an error. What foreign experience shows is not a target number of days, but that the post-acute stage has a classification of its own wherever it has been recognised. That recognition is what the association is after here.
Status of this document
Definition adopted in August 2026, applying to the association's surveys and to every length-of-stay indicator it may publish. It is not ABRAHCT's invention: it is the Brazilian national standard — Ministry of Health Ordinance SAS/MS 312/2002, the ANS QUALISS E-EFI-05 indicator sheet and the ANAHP Observatory use the same formula — applied with the explicit operational rules our segment was missing. The 2025 Sector Diagnosis measured an average length of stay before this definition existed, which is why it is not listed in Sector data: the association will only publish a length-of-stay figure again once it is produced under the definition above.
What is expected of a member: run the calculator with the data from a closed month, see whether the four figures add up and, if they do not, find out which of the four is being measured differently. Nothing is sent to the association at this stage. The next survey will ask for length of stay following this definition, and it is better to find the discrepancy now than after the figure has been published.
Comments and suggestions on the methodology: abrahct@abrahct.org.br