Manual Calculation of Creatinine Clearance

The Creatinine Clearance (CrCl) calculator is available via the GGC Medicines App or on the StaffNet Hub Clinical Info page (NHSGGC network access required). If it is not available, then follow the guidance below to estimate CrCl in your patient.

Estimation of Creatinine Clearance

The following 'Cockcroft Gault' equation is used to estimate CrCl.

CrCl (ml/minute) =	[140 – age (years)] x weight (kg)	x 1.23 (male) OR x 1.04 (female)
	serum creatinine (micromol/L)

Cautions!

Weight used in calculation: Use the patient's actual body weight (ABW) if weight is less than or equal to their ideal body weight (IBW).
- IBW males: IBW = 50kg + 2.3kg for every inch over 5 feet.
- IBW females: IBW = 45.5kg + 2.3kg for each inch over 5 feet.
- It has been agreed within GGC that the above formula can be used to calculate IBW for patients 4 feet 8 inches (142cm) and above. See table 1 below for IBW.
- For patients weighing greater than their IBW, use adjusted body weight (AdjBW):

AdjBW = IBW + 0.4 x (ABW - IBW)

For patients below 4 feet 8 inches (142cm) in height, contact pharmacy for advice.
For patients with amputations, contact pharmacy for advice.
Use 60micromol/L if the creatinine concentration is <60micromol/L.
Do not use eGFR for patients at extremes of weight.
Clinical judgement should be exercised on the applicability of the calculated CrCl result, taking into account individual drugs and patient characteristics.

Table 1: Ideal body weight

Note: For transgender patients, see guidance below.

Height	IBW female (kg)	IBW male (kg)
4 feet 8 inches (142cm)	36.3	40.8
4 feet 9 inches (145cm)	38.6	43.1
4 feet 10 inches (147cm)	40.9	45.4
4 feet 11 inches (150cm)	43.2	47.7
5 feet (152cm)	45.5	50
5 feet 1 inch (155cm)	47.8	52.3
5 feet 2 inch (157cm)	50.1	54.6
5 feet 3 inch (160cm)	52.4	56.9
5 feet 4 inch (163cm)	54.7	59.2
5 feet 5 inch (165cm)	57	61.5
5 feet 6 inch (168cm)	59.3	63.8
5 feet 7 inch (170cm)	61.6	66.1
5 feet 8 inch (173cm)	63.9	68.4
5 feet 9 inch (175cm)	66.2	70.7
5 feet 10 inch (178cm)	68.5	73
5 feet 11 inch (180cm)	70.8	75.3
6 feet (183cm)	73.1	77.6
6 feet 1 inch (185cm)	75.4	79.9
6 feet 2 inch (188cm)	77.7	82.2
6 feet 3 inch (190cm)	80	84.5
6 feet 4 inch (193cm)	82.3	86.8
6 feet 5 inch (196cm)	84.6	89.1
6 feet 6 inch (198cm)	86.9	91.4
6 feet 7 inch (201cm)	89.2	93.7

Transgender patients

For transgender patients (following ≥6 months of hormonal gender affirming therapy or at any time after completion of gender affirming surgery) calculate CrCl and IBW according to the patient's gender identity (see the calculator within the GGC Medicines App or via the StaffNet Hub (link to page only active if connected to NHSGGC network)).

If gender affirming therapy does not meet the criteria above, use the patient's sex at birth according to their electronic records.

Guideline reviewed: January 2025

Page updated: April 2025