Unit conversions show up throughout the TEAS 7 math section, especially in dosage and measurement word problems. Memorize these, and practice setting up proportions so you never have to guess which way to convert.
Metric prefixes
| Prefix | Meaning | Example |
|---|---|---|
| kilo- (k) | 1,000 | 1 kg = 1,000 g |
| centi- (c) | 1/100 | 1 m = 100 cm |
| milli- (m) | 1/1,000 | 1 g = 1,000 mg; 1 L = 1,000 mL |
| micro- (mc / µ) | 1/1,000,000 | 1 mg = 1,000 mcg |
Rule of thumb: going to a smaller unit means more of them, so multiply. Going to a larger unit, divide.
Example: 850 mg = 850 ÷ 1,000 = 0.85 g.
Metric ↔ customary
| Conversion | Value |
|---|---|
| Weight | 1 kg ≈ 2.2 lb |
| Length | 1 in = 2.54 cm |
| Distance | 1 mi ≈ 1.6 km |
| Liquid | 1 fl oz ≈ 30 mL |
| Spoons | 1 tsp = 5 mL; 1 tbsp = 15 mL |
| Cups | 1 cup = 8 fl oz ≈ 240 mL |
Example: A patient weighs 154 lb. 154 ÷ 2.2 = 70 kg.
Customary units
- 1 ft = 12 in · 1 yd = 3 ft · 1 mi = 5,280 ft
- 1 lb = 16 oz
- 1 pint = 2 cups · 1 quart = 2 pints · 1 gallon = 4 quarts
Temperature
- °C = (°F − 32) × 5/9
- °F = °C × 9/5 + 32
Example: 101.3 °F → (101.3 − 32) × 5/9 ≈ 38.5 °C. Body temperature: 37 °C = 98.6 °F.
24-hour (military) time
For times after noon, subtract 1200: 2145 → 9:45 p.m. Midnight is 0000; noon is 1200.
Set up conversions as proportions
Write the conversion as a fraction that cancels the unit you're leaving:
3 tsp × (5 mL / 1 tsp) = 15 mL
Weight-based doses work the same way: an order of 2 mg per 10 kg for a 45 kg patient is 2/10 = x/45, so x = 9 mg.
Practice them under time pressure
Knowing a conversion and using it fast in a word problem are different skills. Try our free TEAS 7 math practice questions or the Measurement & Data review.