Units Conversion Factors and Symbols (SI and Metric) Part 1
Units Conversion Factors (SI and Metric)
What are the types of unit conversion Factors?
- There are two types of unit systems used in the world. These are:
- Metric system.
- SI system
Units Conversion factors formula
- WHO recommends SI units (systeme international d’unities).
What are the SI base units?
| SI unit | Symbol | Used for |
| Kilogram | Kg | Weight |
| Metre | m | Length |
| Seconds | s | Time |
| mole | mol | It is the amount of the substance |
| Kalvin | k | Temperature |
| Ampere | A | Electricity |
| Candela | cd | Luminous intensity |
How will you convert Metric and SI units?
| To convert from | Into | Multiplication factor |
|---|---|---|
| Centimeter | Inches | 0.39 |
| Inches | Centimeter | 2.54 |
| Meter | Yards | 1.09 |
| Yards | Meter | 0.91 |
| Gallons | Liters | 3.78 |
| Liter | Gallons | 0.26 |
| Gallon | Liter | 3.78 |
| Gram | Ounce | 0.035 |
| Ounce | Gram | 28.4 |
| Kilogram | Pound | 2.2 |
| Pound | Kilogram | 0.45 |
| Centigrade ( C ) | Fahrenheit (F) | F = (C x 1.8) + 32 |
| Fahrenheit | Centigrade | C = ( F — 32 ) x 0.556 |
| %weight/volume (weight=w and volume=v) | Molar solution (M) | M = %w/v x 10/gram mol. weight |
| %weight/volume | Normal solution (N) | N = % w/v x 10 /equivalent weight |
| mg/dL | meq/L | meq/L = mg/dL x 10 / equivalent weight |
What Symbols are used with SI units?
| Factor (value) | Prefix | The symbols in the SI system | Divided by |
| 10-1 | deci- | d (10-1) | 10 |
| 10-2 | centi- | c (10-2) | 100 |
| 10-3 | milli- | m (10-3) | 1000 |
| 10-6 | micro- | µ (10-6) | 1 000, 000 |
| 10-9 | nano- | n (10-9) | 1 000, 000, 000 |
| 10-12 | pico- | p (10-12) | 1 000,000,000,000 |
| 10-15 | femto- | f (10-15) | 1 000, 000, 000,000, 000 |
| 10-18 | atto- | a (10-18) | 1 000, 000, 000, 000, 000, 000 |
| Multiply by | |||
| 101 | Deka | da (101) | 10 |
| 102 | hecto- | h (102) | 100 |
| 103 | Kilo- | k (103) | 1000 |
| 106 | mega- | M (106) | 1000,000 |
| 109 | giga- | G (109) | 1000, 000, 000 |
| 1012 | tera- | T (1012) | 1 000, 000, 000, 000 |
What are the unit conversion factors for the old units to SI units?
| Chemical substances | Old units | SI units | Factor from the old unit to the SI unit (multiplication factor) |
| Chemistry | |||
| Albumin | g/dL | g/L | 10 |
| Protein total | g/dL | g/L | 10 |
| Bilirubin | mg/dL | µmol/L | 17.1 |
| Calcium | mg/dL and meq/L | mmol/L | 0.25 |
| Sodium | meq/L | mmol/L | 1 |
| Magnesium | mg/dL | mmol/L | 0.411 |
| Potassium | meq/L | mmol/L | 1 |
| Iron | µg/dL | µmol/L | 0.179 |
| Phosphate (inorganic) | mg/dL | mmol/L | 0.323 |
| Creatinine | mg/dL | mmol/L | 0.088 |
| Urea nitrogen | mg/dL | mmol/L | 0.167 |
| Uric acid | mg/dL | mmol/L | 0.06 |
| Glucose | mg/dL | mmol/L | 0.0555 |
| Bicarbonate | meq/L | mmol/L | 1 |
| Anion gap | meq/L | mmol/L | 1 |
| Carbon dioxide total | meq/L | mmol/L | 1 |
| Chloride | meq/? or mg/dL | mmol/L | 1 |
| Cholesterol | mg/dL | mmol/L | 0.026 |
| Hematology | |||
| Iron total | µg/dL | µmol/L | 0.179 |
| Iron binding capacity | µg/dL | µmol/L | 0.179 |
| Hemoglobin | g/dL | mmol/L | 0.155 |
| Fibrinogen | g/dL | g/L | 10 |
| Platelets count | 103 µL | 109/L | 1 |
| Reticulocytes | % | 109/L | 0.001 |
| Mean corpuscular volume (MCV) | µ3 (Cubic micron) | fL | 1 |
| Hematocrit (PCV) | % | volume fraction | 0.01 |
| Hormones | |||
| Testosterone | ng/dL | nmol/L | 0.0347 |
| Thyroglobulin | ng/mL | µg/L | 1 |
| TSH | µU/mL | mIU/L | 1 |
| Aldosterone | ng/dL | nmol/L | 0.0277 |
| Antidiuretic hormone (ADH) | pg/mL | ng/L | 1 |
Please see Part 2