Key Takeaways
- Metric system is based on powers of 10; use prefixes kilo-, centi-, milli-
- To convert to smaller units, multiply; to larger units, divide
- Key conversion: 1 kg = 2.2 lbs; 2.54 cm = 1 inch
- Temperature: °F = (°C × 9/5) + 32; °C = (°F - 32) × 5/9
- Dimensional analysis uses conversion factors arranged so units cancel
Last updated: January 2026
Measurement and Unit Conversions
Accurate measurement and unit conversion are critical nursing skills. The TEAS tests your ability to convert within and between measurement systems.
Metric System
The metric system is based on powers of 10.
Common Prefixes:
| Prefix | Symbol | Value | Example |
|---|---|---|---|
| kilo- | k | 1,000 | 1 kg = 1,000 g |
| hecto- | h | 100 | 1 hL = 100 L |
| deka- | da | 10 | 1 daL = 10 L |
| (base) | — | 1 | gram, liter, meter |
| deci- | d | 0.1 | 1 dL = 0.1 L |
| centi- | c | 0.01 | 1 cm = 0.01 m |
| milli- | m | 0.001 | 1 mL = 0.001 L |
| micro- | mcg/μ | 0.000001 | 1 mcg = 0.000001 g |
Metric Conversions
To convert within metric:
- Moving to a smaller unit → multiply (move decimal right)
- Moving to a larger unit → divide (move decimal left)
Common Metric Conversions:
| Conversion | Relationship |
|---|---|
| kg to g | × 1,000 |
| g to mg | × 1,000 |
| mg to mcg | × 1,000 |
| L to mL | × 1,000 |
| m to cm | × 100 |
| cm to mm | × 10 |
Example: Convert 2.5 kg to grams
- 2.5 × 1,000 = 2,500 g
Example: Convert 750 mL to liters
- 750 ÷ 1,000 = 0.75 L
U.S. Customary System
| Measure | Equivalents |
|---|---|
| Length | 12 inches = 1 foot; 3 feet = 1 yard; 5,280 feet = 1 mile |
| Weight | 16 ounces = 1 pound; 2,000 pounds = 1 ton |
| Volume | 8 oz = 1 cup; 2 cups = 1 pint; 2 pints = 1 quart; 4 quarts = 1 gallon |
Metric to U.S. Conversions
| Metric | U.S. Approximation |
|---|---|
| 1 kg | 2.2 pounds |
| 1 inch | 2.54 cm |
| 1 liter | 1.06 quarts |
| 1 meter | 3.28 feet |
| 30 mL | 1 fluid ounce |
| 5 mL | 1 teaspoon |
| 15 mL | 1 tablespoon |
Temperature Conversions
Celsius to Fahrenheit: °F = (°C × 9/5) + 32
Fahrenheit to Celsius: °C = (°F - 32) × 5/9
| Celsius | Fahrenheit | Reference |
|---|---|---|
| 0°C | 32°F | Freezing |
| 37°C | 98.6°F | Normal body temp |
| 100°C | 212°F | Boiling |
Time Conversions
| Conversion | Relationship |
|---|---|
| Seconds to minutes | ÷ 60 |
| Minutes to hours | ÷ 60 |
| Hours to days | ÷ 24 |
| Military to standard | Subtract 12 if > 12:00 |
Military Time Examples:
- 0800 = 8:00 AM
- 1300 = 1:00 PM
- 2100 = 9:00 PM
Dimensional Analysis
Dimensional analysis uses conversion factors to change units.
Example: Convert 165 pounds to kilograms
165 lbs × (1 kg / 2.2 lbs) = 75 kg
Example: Convert 2 hours to seconds
2 hours × (60 min / 1 hour) × (60 sec / 1 min) = 7,200 seconds
Healthcare Measurement Applications
| Application | Common Units |
|---|---|
| Medication dosage | mg, mcg, g |
| IV fluids | mL, L |
| Patient weight | kg, lbs |
| Temperature | °C, °F |
| Blood pressure | mmHg |
| Height | cm, inches, feet |
Test Your Knowledge
Convert 4,500 mg to grams.
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Test Your Knowledge
A patient weighs 176 lbs. What is their weight in kilograms? (Use 1 kg = 2.2 lbs)
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D
Test Your Knowledge
Convert 38.5°C to Fahrenheit.
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