Measuring weight and height

Measuring weight and height can be important in monitoring disease progression. Changes in weight can act as an indicator of changes in health of an individual and help healthcare professionals monitor the progression or remission of disease. 

The measurement of weight and height may be undertaken using a variety of means, although all need to be accurate. Height and weight measurement may be clinically important to:

• establish a baseline prior to surgery or other treatment
• monitor the progression and severity of an illness
• establish dosing for the administration of medications or other treatments
• monitor for the risk of some clinical issues, eg pressure sores
• monitor the effectiveness of an intervention, eg weight loss or gain
• estimate fluid loss or gain, eg in kidney disease (National Institute for Health and Care Excellence, 2014; Dobson and Simpson, 2022; Ellis et al, 2023)

Nurses need to be conversant with the methods of, and reasons for, measuring and monitoring a patient’s weights and height. They should consider the ways in which measurements are gained, their accuracy, frequency and recording. Understanding and being able to respond to changes in an individuals weight may be important in identifying disease progression and remission as well as identifying risk in some patients. 

Individual weights are often not as important as trends in weight loss and weight gain. Therefore, nurses need to consider not only the frequency of measurement, but accuracy and consistency, for example using the same device at the same time of day under the same conditions.

Measuring height is usually a one-off event in care settings and is generally used to ascertain a body mass index for the individual.

The equipment required for measuring weight will depend on the individual’s ability to stand or sit unaided.

• if the person can stand, use standing scales
• if the person can sit, use seated scales
• if the person is a wheelchair user, use a wheelchair scale
• if the person can be hoisted, use a hoist scale
• if the person cannot be hoisted, consider alternatives such as anthropometry, eg mid arm muscle circumference, or bed scales
• the patient’s record, eg a weight chart

The equipment required for measuring height will depend on the individual’s ability to stand. 

• if the person can stand, a stadiometer is preferred
• a pencil and a flat wall (if stadiometer not available)
• a tape measure for people who are confined to bed
• the patient’s record

The nurse must ensure they gain consent when measuring weight and height, ensuring the patient understands the reason for the measurement and what the procedure entails. Nurses should observe hand hygiene procedures prior to measuring weight or height to limit the spread of infection. The nurse should attend to any privacy and dignity issues associated with the procedure.

Measuring weight

Before weighing a person by any means, the nurse should visually assess the patient to ascertain whether they appear over or underweight, and where they are known to the nurse, whether this appears to have changed. To measure a patient’s weight, nurses must:

• try to use the same scales each time
• ensure the scales are properly located on a flat solid surface
• make sure the scales are not touching a wall or other object
• ensure the scales are reading zero when turned on (Shaw et al, 2021)
• ensure

Failure to maintain and calibrate weighing equipment and/or poorly executed weighing procedures, eg with a moving patient, can lead to highly inaccurate weight measurements which may prove misleading when planning patient care, eg medication dosages or dietary requirements.

Similarly, poorly undertaken measurements of height can mean inaccurate estimations of an individual’s body mass index, which can have deleterious effects on their subsequent treatment. Nurses should note that patients will have an idea about what their height is, although this will decrease as the person ages and so may be less that they expected it to be (Shaw et al, 2021).

Nurses should familiarise themselves with the processes in place where they work for measuring height and weight. Where the nurse is responsible for equipment, they should ensure it is calibrated and maintained as per the manufacturer’s instructions.

Nursing and Midwifery Council: standards of proficiency for registered nurses

Part 1: Procedures for assessing people’s needs for person-centred care

1. Use evidence-based, best practice approaches to take a history, observe, recognise and accurately assess people of all ages

2.6 accurately measure weight and height, calculate body mass index and recognise healthy ranges and clinically significant low/high readings

Part 2: Procedures for the planning, provision and management of person-centred nursing care

7.3 use appropriate moving and handling equipment to support people with impaired mobility

Best C, Shepherd E. Accurate measurement of weight and height 1: weighing patients. N Times. 2020a;116(4):50-52

Best C, Shepherd E. Accurate measurement of weight and height 2: calculating height and BMI. N Times. 2020b;116(5):42-44

Ellis P, Standing M. Patient assessment and care planning in nursing. 4th edn. London: Sage; 2023

Evans L, Best C. Accurate assessment of patient weight. N Times. 2014;110(12):12-14

Dobson C, Simpson T. Clinical measurement. In: Delves-Yates C (ed). Essentials of nursing practice. London: Sage; 2022

National Institute for Health and Care Excellence. Weight management: lifestyle services for overweight or obese adults. 2014.  https://www.nice.org.uk/guidance/PH53 (accessed 29 January 2024)

Shaw C, Askins L, Brady G  et al. Nutrition and fluid balance. In: Lister S, Hofland J, Grafton H, Wilson C (eds). The Royal Marsden Manual of clinical nursing procedures. 10^th edn. Chichester: Wiley Blackwell; 2021:339-402