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PT Assessment Calculator — Balance, Mobility & ARDS Tools

Berg Balance Scale, Elderly Mobility Scale, tidal volume (Devine/ARDSNet), and PF ratio (Berlin ARDS) calculators for PT and allied health assessment scoring.

Score each of the 14 items 0–4 based on direct observation of the patient performing the task. This tool totals and interprets the score — it does not replace hands-on training in administering the test.

Low fall risk
56 / 56

Cutoffs: 41–56 = low fall risk, 21–40 = medium fall risk, 0–20 = high fall risk (Berg et al., 1992). A score below 45 is also widely cited as a single at-risk threshold. Different populations (e.g., chronic stroke, nursing home residents) sometimes use other condition-specific cutoffs — treat these as general guidance, not a diagnosis.
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Reference Values

Last verified:
Category Range What It Means Status
Berg Balance Scale — 14 items 0–4 points each (56 max) Sitting to standing, standing unsupported, sitting unsupported, standing to sitting, transfers, standing with eyes closed, standing with feet together, reaching forward, retrieving object from floor, turning to look behind, turning 360°, alternate foot on stool, tandem stance, standing on one leg. Good
Berg Balance Scale: 41–56 ★ Low fall risk Original Berg et al. (1992) three-band interpretation. ★ Best
Berg Balance Scale: 21–40 Medium fall risk Further balance intervention typically recommended. Okay
Berg Balance Scale: 0–20 High fall risk Strongly associated with fall history in most validation studies. Poor
Berg Balance Scale single cutoff Below 45 Commonly cited single at-risk threshold, used alongside (not instead of) the three-band interpretation above. Good
Elderly Mobility Scale (EMS) — 7 items 0–20 total (simplified scoring aid) Lying to sitting, sitting to lying, sitting to standing, standing, gait, timed walk, functional reach. Published per-item point breakdown is not fully confirmable from accessible public sources — item max scores here (2/2/3/3/3/4/3) are a simplified aid that still totals to the standard 0–20 range. Good
EMS: 15–20 ★ Normal mobility / independent Non-fallers and single-fallers typically score in this range. ★ Best
EMS: 10–14 Borderline mobility May need some assistance; below 14 is commonly cited as an increased-risk threshold. Okay
EMS: below 10 Significant assistance needed Associated with dependence in basic mobility and ADLs. Poor
Devine formula (Male PBW) 50 + 2.3×(height in − 60) kg Predicted/ideal body weight from height, used for tidal volume dosing. Good
Devine formula (Female PBW) 45.5 + 2.3×(height in − 60) kg Predicted/ideal body weight from height, used for tidal volume dosing. Good
Normal spontaneous tidal volume 7–8 mL/kg PBW Typical resting tidal volume range for a spontaneously breathing adult. Good
ARDSNet lung-protective target ★ 6 mL/kg PBW Low-tidal-volume ventilation strategy shown to reduce mortality in ARDS. ★ Best
PF ratio: above 300 ★ Normal / no ARDS by oxygenation criteria Does not meet Berlin ARDS oxygenation impairment threshold. ★ Best
PF ratio: 200–300 Mild ARDS Berlin Definition of ARDS (2012). Good
PF ratio: 100–200 Moderate ARDS Berlin Definition of ARDS (2012). Okay
PF ratio: 100 or below Severe ARDS Berlin Definition of ARDS (2012). Poor
PF ratio PEEP requirement PEEP or CPAP ≥ 5 cmH₂O Required alongside the PF ratio and bilateral opacities for a full Berlin ARDS diagnosis — this calculator checks the oxygenation math only. Good

Source: Berg Balance Scale: Berg K, Wood-Dauphinee S, Williams JI, Maki B (1992) validation study, cross-referenced with SRALab Rehabilitation Measures Database and Physiopedia summaries. Elderly Mobility Scale: Smith R (1994) original development study, item list per SRALab/APTA/Physiopedia summaries (per-item point allocation simplified here as noted). Tidal volume: Devine BJ (1974) formula; ARDSNet (NEJM 2000, 'Ventilation with Lower Tidal Volumes'). PF ratio: ARDS Definition Task Force, 'Acute Respiratory Distress Syndrome: The Berlin Definition,' JAMA 2012.

Worked Examples

Berg Balance Scale: Post-Stroke Outpatient

Item scores
14 items summing to 42/56
42/56 — Low fall risk (but below the <45 single cutoff)

42 falls in the 41–56 low-risk band, but is still below the commonly cited <45 single at-risk threshold — a reminder that the three-band cutoffs and the single cutoff can disagree slightly, and both are worth noting in documentation.

Elderly Mobility Scale: Post-Fall Assessment

Item scores
7 items summing to 16/20
16/20 — Normal mobility / independent

16 clears the 15–20 normal-mobility band, consistent with a patient who is close to their prior baseline after a fall with no major mobility deficit found on assessment.

Tidal Volume: Male, 5'7" (67 in)

Sex
Male
Height
67 in
PBW 66.1 kg → Normal TV 463–529 mL, ARDSNet target 397 mL

PBW = 50 + 2.3×(67−60) = 50 + 16.1 = 66.1 kg. Normal spontaneous tidal volume = 66.1×7 to 66.1×8 = 463 to 529 mL. ARDSNet lung-protective target = 66.1×6 = 397 mL.

PF Ratio: Moderate ARDS

PaO2
90 mmHg
FiO2
60%
PF = 150 — Moderate ARDS

PF ratio = 90 ÷ 0.60 = 150, which falls in the Berlin Definition's Moderate ARDS band (100–200) — assuming PEEP/CPAP ≥5 cmH₂O and bilateral opacities are also present, since PF ratio alone doesn't complete the diagnosis.

How to Use This Calculator

  1. 1

    Pick a tool

    Berg Balance Scale, Elderly Mobility Scale, Tidal Volume, or PF Ratio — each tab works independently.

  2. 2

    Berg Balance Scale: score all 14 items

    Rate each observed task 0 (unable/unsafe) to 4 (independent) using the dropdowns; the total and fall-risk category update instantly.

  3. 3

    Elderly Mobility Scale: score all 7 items

    Rate each item using the level-of-assistance dropdown; totals use the standard 0–20 scale (simplified per-item aid, noted in the tool).

  4. 4

    Tidal Volume: enter height + sex, or PBW directly

    Get predicted body weight (Devine formula), the normal 7–8 mL/kg range, and the ARDSNet 6 mL/kg lung-protective target.

  5. 5

    PF Ratio: enter PaO2 and FiO2

    FiO2 can be entered as a percent (60) or decimal (0.6) — the calculator classifies the result per the Berlin ARDS criteria.

What Each Value Means

Berg Balance Score (points (0–56))
Sum of 14 observed balance items, each scored 0–4, for a maximum of 56 points. Lower scores indicate higher fall risk.
Elderly Mobility Scale (EMS) Score (points (0–20))
Sum of 7 functional mobility items, scored on a simplified aid that totals to the standard published 0–20 range. Higher scores indicate greater independence.
Predicted Body Weight (PBW) (kg)
Weight estimated from height and sex using the Devine formula, used instead of actual body weight to set safe mechanical ventilation tidal volumes.
PF Ratio (PaO2/FiO2) (ratio (mmHg))
Arterial oxygen partial pressure divided by the fraction of inspired oxygen — the core oxygenation-impairment measure in the Berlin Definition of ARDS.

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Frequently Asked Questions

What is the Berg Balance Scale and how is it scored?
The Berg Balance Scale (BBS) is a 14-item test of functional balance, developed by Berg et al. (1992). A trained clinician observes the patient perform tasks like standing unsupported, reaching forward, and standing on one leg, scoring each item from 0 (unable/unsafe) to 4 (independent, meets criteria) for a maximum of 56 points. Total scores of 41–56 indicate low fall risk, 21–40 medium risk, and 0–20 high risk, with a score below 45 also commonly cited as a single at-risk threshold.
What does an Elderly Mobility Scale (EMS) score mean?
The EMS is a 7-item mobility test (lying to sitting, sitting to lying, sitting to standing, standing, gait, timed walk, and functional reach) developed by Smith (1994), scored 0–20. Scores of 15–20 suggest normal, independent mobility; 10–14 is borderline and may need some assistance; below 10 suggests significant assistance is needed. A score below 14 is also commonly cited as an increased fall-risk threshold. Because the exact published per-item point breakdown isn't consistently available in accessible sources, this calculator uses a simplified item-scoring aid that still totals to the standard 0–20 range — treat it as an interpretation aid, not a replacement for the original instrument.
How do you calculate tidal volume for lung-protective ventilation?
Tidal volume targets are based on predicted body weight (PBW), not actual body weight. Using the Devine formula, Male PBW(kg) = 50 + 2.3×(height in inches − 60), and Female PBW(kg) = 45.5 + 2.3×(height in inches − 60). A normal spontaneous tidal volume is roughly 7–8 mL/kg PBW, while the ARDSNet lung-protective ventilation strategy targets 6 mL/kg PBW — a difference that matters most for obese patients, since basing tidal volume on actual weight instead of PBW can significantly over-ventilate the lungs.
What is a PF ratio and how is ARDS severity classified?
The PF ratio (PaO₂/FiO₂) divides arterial oxygen partial pressure (mmHg) by the fraction of inspired oxygen (as a decimal). Under the Berlin Definition of ARDS (2012), a PF ratio of 200–300 indicates mild ARDS, 100–200 indicates moderate ARDS, and 100 or below indicates severe ARDS. A PF ratio in these ranges only completes an ARDS diagnosis when paired with PEEP or CPAP of at least 5 cmH₂O and bilateral opacities on imaging not fully explained by fluid overload or heart failure — this calculator checks the oxygenation math only, not the full diagnostic picture.
Can this calculator replace formal training in giving the Berg Balance Scale or EMS?
No. Both the Berg Balance Scale and Elderly Mobility Scale require a trained clinician to physically observe the patient perform each task and judge safety, technique, and level of assistance needed in real time — that judgment can't be replicated by a self-report form. This tool only totals the scores you enter and applies the published interpretation cutoffs; administering the assessment itself still requires the training and clinical judgment of a physical therapist, occupational therapist, or other qualified healthcare professional.