Math for Nurses
Goals
- Review the math every nurse needs, from fractions and decimals to unit conversions.
- Calculate doses for tablets, liquids, injections and weight-based orders.
- Work out IV rates, drip rates and infusion times.
- Check yourself with a quiz and a practice test.
Jump to a section
The Math for Nurses Series
- 🩺 Math for Nurses (start here)
- 🧮 1. Math Skills
- 📏 2. Conversions
- 💊 3. Dosage Calculations
- ⚖️ 4. Weight-Based and Pediatric
- 💧 5. IV Calculations
Nursing Math Quiz
10 new questions every time, drawn from all five lessons. Each answer comes with a step-by-step explanation.
Quiz completed … times
Loading…
Your score
Why Nurses Need Math
We will cover math for nurses thoroughly on this page. We hope you will ace your NCLEX, land a great job in nursing, and make lots of money.
Every day, nurses turn a provider’s order and a medication label into the exact amount to give: how many tablets, how many milliliters, how many drops per minute. A misplaced decimal point can make a dose 10 times too large, so the math has to be right every time.
This page is the starting point of a five-lesson series that covers all the math in a nursing dosage calculation course, from fractions to critical care drips. Work through the lessons in order, or jump to the one you need. Test yourself with the quiz above, then try the practice test below.
Note: Schools and hospitals set their own rules for rounding and some conversions. Always follow your program’s and facility’s policy, and double-check high-alert medications such as insulin and heparin with a second nurse.
The Five Lessons
Each lesson explains every topic step by step, with worked examples and practice problems with answers.
🧮 1. Math Skills for Nurses
The math underneath every dose.
- Roman numerals
- Fractions: simplify, compare, add, subtract, multiply, divide
- Decimals: compare, operations, × and ÷ by 10, 100, 1,000, rounding
- Percents and ratio strength
- Ratios, proportions, and solving for x
- Order of operations and canceling units
📏 2. Conversions for Nurses
Getting the order and the label into the same unit.
- Metric units (kg, g, mg, mcg, L, mL)
- Household measures (tsp, Tbsp, oz, cup)
- Pounds, ounces, kilograms, inches, centimeters
- Fahrenheit and Celsius
- 24-hour time, elapsed time, finish times
- Intake and output
💊 3. Dosage Calculations
How much to give, for every common form.
- Reading the order and label (D, H, Q)
- Writing numbers safely
- Formula, ratio and proportion, and dimensional analysis
- Tablets, liquids, and injections
- Reading syringes
- Reconstitution, insulin, heparin, mEq, and percent drugs
⚖️ 4. Weight-Based and Pediatric
Doses that depend on the patient’s size.
- mg/kg and mcg/kg doses
- Daily doses split into several doses
- Checking safe dose ranges and maximums
- Body surface area (BSA)
- Maintenance fluids (100/50/20 and 4-2-1)
💧 5. IV Calculations
Rates, times, and continuous infusions.
- mL/hr and gtt/min
- Infusion time, finish time, and volume infused
- Recalculating a rate that is behind
- IV piggybacks, percent solutions, and dilutions
- Heparin and insulin drips (units/hr)
- mg/hr, mcg/min, and mcg/kg/min
Key Formulas
A quick reference. The lessons explain each one.
Dose to give
500 mg250 mg × 5 mL = 10 mL
Pounds to kilograms
1542.2 = 70 kg
Weight-based dose
15 mg/kg × 20 kg = 300 mg
Pump rate
1,0008 = 125 mL/hr
Drip rate
1,000 × 15480 = 31 gtt/min
Infusion time
500125 = 4 hours
Units/hr to mL/hr
1,00050 = 20 mL/hr
mcg/kg/min to mL/hr
5 × 80 × 601,600 = 15 mL/hr
Body surface area
√120 × 253,600 ≈ 0.91 m²
Temperature
(101.3 − 32) × 59 = 38.5 °C
Practice Test
Understanding the math concepts below is extremely important to do well in nursing. Trying to take the test below with 100% accuracy should definitely be your goal before moving on.
Which decimal has the smallest value in each of the following?
- a) 6.7 b) 5.8 c) 4.5
- a) 2.6 b) 2.4 c) 2.8
- a) 8.54 b) 8.58 c) 8.59
Show answers
- c) 4.5
- b) 2.4
- a) 8.54
Add the following decimals.
- 2.6 + 1.4
- 1.3 + 0.04
- 6.21 + 15.8 + 7.34
Show answers
- 4
- 1.34
- 29.35
Subtract the following decimals.
- 4.2 − 0.58
- 26.51 − 6.11
- 6.347 − 0.086
Show answers
- 3.62
- 20.4
- 6.261
Express the following numbers to the nearest tenth.
- 4.26
- 0.25
- 13.82
Show answers
- 4.3
- 0.3
- 13.8
Express the following numbers to the nearest hundredth.
- 1.479
- 12.105
- 4.35
Show answers
- 1.48
- 12.11
- 4.35 (it already has two decimal places)
Solve the following problems.
- Tablets have a strength of 0.1 mg and 0.3 mg is ordered. How many tablets should the patient take?
- Some tablets ordered for a patient have a strength of 2.25 mg and 6.75 mg is ordered. How many tablets should you give to the patient?
- Tablets are labeled 0.6 mg. If 0.3 mg is ordered, how many tablets will you give to the patient?
Show answers
- 3 tablets (0.3 mg0.1 mg = 3)
- 3 tablets (6.75 mg2.25 mg = 3)
- ½ tablet (0.3 mg0.6 mg = 0.5)
More practice: Tablet dosage calculation
Multiply the following decimals and then express your answers to the nearest tenth.
- 0.5 × 2.4
- 1.7 × 2.8
- 6.3 × 0.34 × 1.1
Show answers
- 1.2
- 4.76 ≈ 4.8
- 2.3562 ≈ 2.4
Divide the following decimals and then express your answers to the nearest hundredth.
- 18.9 ÷ 2.1
- 4 ÷ 0.75
- 8.27 ÷ 2.7
Show answers
- 9 (9.00)
- 5.333… ≈ 5.33
- 3.0629… ≈ 3.06
Get an answer to the multiplication of fractions below.
These have the same shape as the dosage formula DH × Q, so they are great practice.
- 14 × 412
- 340120 × 145400
- 0.92.25 × 4.250.18
- 42,0001,200 × 212
- 3.52.5 × 0.050.25
Show answers
- 112 (about 0.08)
- 493480 ≈ 1.03
- 859 ≈ 9.44
- 367.5
- 0.28
More practice: Oral dosage solution calculation
Keep learning