Converting between standard (metric) and conventional units in order to interpret haematological or biochemical data, or to select the correct equipment for surgery, can be problematic and time-consuming. BSAVA have put together a handy guide for the most common conversions required in small animal practice.
Temperature
| SI unit |
Conversion factor |
Conventional unit |
| ° C |
(x 9/5) + 32 |
° F |
Haematology
| |
SI unit |
Conversion factor |
Conventional unit |
| Red blood cell count |
1012/l |
1 |
106/µl |
| Haemoglobin |
g/l |
0.1 |
g/dl |
| MCH |
pg/cell |
1 |
pg/cell |
| MCHC |
g/l |
0.1 |
g/dl |
| MCV |
fl |
1 |
µm3 |
| Platelet count |
109/l |
1 |
103/ µl |
| White blood cell count |
109/l |
1 |
103/ µl |
Biochemistry
| |
SI unit |
Conversion factor |
Conventional unit |
| Alanine aminotransferase |
IU/l |
1 |
IU/l |
| Albumin |
g/l |
0.1 |
g/dl |
| Alkaline phosphatase |
IU/l |
1 |
IU/l |
| Aspartate aminotransferase |
IU/l |
1 |
IU/l |
| Bilirubin |
µmol/l |
0.0584 |
mg/dl |
| BUN |
mmol/l |
2.8 |
mg/dl |
| Calcium |
mmol/l |
4 |
mg/dl |
| Carbon dioxide (total) |
mmol/l |
1 |
mEq/l |
| Cholesterol |
mmol/l |
38.61 |
mg/dl |
| Chloride |
mmol/l |
1 |
mEq/l |
| Cortisol |
nmol/l |
0.362 |
ng/ml |
| Creatine kinase |
IU/l |
1 |
IU/l |
| Creatinine |
µmol/l |
0.0113 |
mg/dl |
| Glucose |
mmol/l |
18.02 |
mg/dl |
| Insulin |
pmol/l |
0.1394 |
µIU/ml |
| Iron |
µmol/l |
5.587 |
µg/dl |
| Magnesium |
mmol/l |
2 |
mEq/l |
| Phosphorus |
mmol/l |
3.1 |
mg/dl |
| Potassium |
mmol/l |
1 |
mEq/l |
| Sodium |
mmol/l |
1 |
mEq/l |
| Total protein |
g/l |
0.1 |
g/dl |
| Thyroxine (T4) (free) |
pmol/l |
0.0775 |
ng/dl |
| Thyroxine (T4) (total) |
nmol/l |
0.0775 |
µg/dl |
| Tri-iodothyronine (T3) |
nmol/l |
65.1 |
ng/dl |
| Triglycerides |
mmol/l |
88.5 |
mg/dl |
Hypodermic needles
| |
Metric |
Non-metric |
| Needle gauge |
0.8 mm |
21 G |
| |
0.6 mm |
23 G |
| |
0.5 mm |
25 G |
| |
0.4 mm |
27 G |
| Needle length |
12 mm |
1/2 inch |
| |
16 mm |
5/8 inch |
| |
25 mm |
1 inch |
| |
30 mm |
1.25 inch |
| |
40 mm |
1.5 inch |
Suture material sizes
| Metric (Ph. Eur.) |
USP |
| 0.4 |
8/0 |
| 0.5 |
7/0 |
| 0.7 |
6/0 |
| 1 |
5/0 |
| 1.5 |
4/0 |
| 2 |
3/0 |
| 3 |
2/0 |
| 3.5 |
0 |
| 4 |
1 |
| 5 |
2 |
| 6 |
3 |