Nursing Unit Conversion Calculator
Convert the units used in medication math and patient care: g, mg and mcg; L and mL; pounds and kilograms; teaspoons, tablespoons and ounces; inches and cm; °F and °C.
Formula
1 g = 1,000 mg · 1 mg = 1,000 mcg · 1 L = 1,000 mL
1 kg = 2.2 lb · 1 inch = 2.54 cm
1 tsp = 5 mL · 1 tbsp = 15 mL · 1 fl oz = 30 mL · 1 cup = 240 mL
°C = (°F − 32) × 5 ÷ 9 · °F = °C × 9 ÷ 5 + 32
How to calculate it step by step
- Find the conversion factor between the two units.
- From a larger unit to a smaller one (g to mg), multiply. From a smaller unit to a larger one (mcg to mg), divide.
- Check the answer: the number gets bigger when the unit gets smaller.
Worked examples
Example 1. A client drank 4 fl oz of juice. How many mL is that for the intake record?
- 1 fl oz = 30 mL: 4 × 30 = 120 mL.
Answer: 120 mL
Example 2. A client drank 8 fl oz of juice. How many mL is that for the intake record?
- 1 fl oz = 30 mL: 8 × 30 = 240 mL.
Answer: 240 mL
Rounding
Round kg and lb to the tenth, temperatures to the tenth. Keep the leading zero and drop trailing zeros (0.25 mg, not .25 mg or 0.250 mg).
Common mistakes
- Moving the decimal point the wrong way between mg and mcg: a 1,000-fold error.
- Multiplying by 2.2 when converting pounds to kilograms (divide by 2.2).
- Using a kitchen teaspoon to measure a liquid dose.
Nursing safety points
- Write mcg, not µg, which can be misread as mg.
- Weigh and document patients in kilograms to avoid conversion errors in dosing.
Frequently asked questions
How many mcg are in 1 mg?
1,000 mcg. To convert mg to mcg, multiply by 1,000 (0.125 mg = 125 mcg).
How do you convert pounds to kilograms?
Divide by 2.2. 154 lb ÷ 2.2 = 70 kg.
How many mL are in 1 ounce?
Nursing math uses 1 fluid ounce = 30 mL (the exact value is 29.57 mL).