ORIGINAL STUDY GUIDE
Dosage Calculation
Worked Examples & Practice for Nursing Students
Concept review + original practice questions with rationales
For nursing students — not affiliated with NCLEX®, ATI®, or HESI®
, About this guide. This is original educational material written to help you learn core nursing concepts. All practice
questions were written from scratch for this guide. It is a study aid, not real or recalled exam content, and is not affiliated
with or endorsed by any testing organization.
The One Method That Works Every Time
You do not need to memorize a different formula for every scenario. Dimensional analysis lets you solve
almost any dosage problem by lining up units so unwanted ones cancel. This guide teaches that method, then
applies it to the common problem types with fully worked examples.
Essential Conversions
Unit Equivalent
1 kg 2.2 lb
1g 1000 mg
1 mg 1000 mcg
1L 1000 mL
1 tsp 5 mL
1 tbsp 15 mL
1 oz 30 mL
Method: Dimensional Analysis
Start with what you want to find on the left. Multiply by fractions built from your known values, arranging
each so the unit you want to cancel sits diagonally opposite itself. Cancel units, then multiply across the top
and divide by the bottom.
Worked Example 1 — Basic tablet
Problem: Order: 500 mg. Available: 250 mg tablets. How many tablets?
Setup: 500 mg × (1 tablet / 250 mg) = 500/250 = 2 tablets.
Worked Example 2 — Liquid medication
Problem: Order: 375 mg. Available: 250 mg per 5 mL. How many mL?
Setup: 375 mg × (5 mL / 250 mg) = 1875/250 = 7.5 mL.
Worked Example 3 — Weight-based dose
Problem: Order: 5 mg/kg/day. Client weighs 44 lb. What is the daily dose in mg?
Step 1 — convert weight: 44 lb × (1 kg / 2.2 lb) = 20 kg.
Step 2 — calculate dose: 20 kg × 5 mg/kg = 100 mg/day.
IV Flow Rate Calculations
mL per hour (pump)
Formula: mL/hr = total volume (mL) ÷ total time (hr).
Example: 1000 mL over 8 hours = 1000 ÷ 8 = 125 mL/hr.
Dosage Calculation
Worked Examples & Practice for Nursing Students
Concept review + original practice questions with rationales
For nursing students — not affiliated with NCLEX®, ATI®, or HESI®
, About this guide. This is original educational material written to help you learn core nursing concepts. All practice
questions were written from scratch for this guide. It is a study aid, not real or recalled exam content, and is not affiliated
with or endorsed by any testing organization.
The One Method That Works Every Time
You do not need to memorize a different formula for every scenario. Dimensional analysis lets you solve
almost any dosage problem by lining up units so unwanted ones cancel. This guide teaches that method, then
applies it to the common problem types with fully worked examples.
Essential Conversions
Unit Equivalent
1 kg 2.2 lb
1g 1000 mg
1 mg 1000 mcg
1L 1000 mL
1 tsp 5 mL
1 tbsp 15 mL
1 oz 30 mL
Method: Dimensional Analysis
Start with what you want to find on the left. Multiply by fractions built from your known values, arranging
each so the unit you want to cancel sits diagonally opposite itself. Cancel units, then multiply across the top
and divide by the bottom.
Worked Example 1 — Basic tablet
Problem: Order: 500 mg. Available: 250 mg tablets. How many tablets?
Setup: 500 mg × (1 tablet / 250 mg) = 500/250 = 2 tablets.
Worked Example 2 — Liquid medication
Problem: Order: 375 mg. Available: 250 mg per 5 mL. How many mL?
Setup: 375 mg × (5 mL / 250 mg) = 1875/250 = 7.5 mL.
Worked Example 3 — Weight-based dose
Problem: Order: 5 mg/kg/day. Client weighs 44 lb. What is the daily dose in mg?
Step 1 — convert weight: 44 lb × (1 kg / 2.2 lb) = 20 kg.
Step 2 — calculate dose: 20 kg × 5 mg/kg = 100 mg/day.
IV Flow Rate Calculations
mL per hour (pump)
Formula: mL/hr = total volume (mL) ÷ total time (hr).
Example: 1000 mL over 8 hours = 1000 ÷ 8 = 125 mL/hr.
