Reference

Nursing Math Cheat Sheet

The NursingCalc nursing math cheat sheet collects every essential formula, normal laboratory value, unit conversion factor, and clinical reference table a nurse needs in one place. Bookmark this page for instant access during nursing school study, NCLEX preparation, and clinical practice. All formulas are sourced from peer-reviewed references and verified against current clinical guidelines.

💊 Drug Calculation Formulas

Liquid Drug Dose
Volume = (Desired ÷ Have) × Quantity
Tablets / Capsules
Tablets = (Desired ÷ Have) × 1 tablet
Pediatric (mg/kg)
Dose = Weight (kg) × mg/kg ordered
BSA Dose
Dose = BSA (m²) × dose/m²

💧 IV Calculation Formulas

IV Flow Rate (mL/hr)
Rate = Volume (mL) ÷ Time (hrs)
IV Drip Rate (gtt/min)
gtt/min = (Vol × Drop factor) ÷ (Time hrs × 60)
Infusion Duration
Hours = Volume (mL) ÷ Rate (mL/hr)
mcg/kg/min → mL/hr
mL/hr = (mcg/kg/min × kg × 60) ÷ mcg/mL conc.

🧮 Body Measurement Formulas

BMI
BMI = Weight (kg) ÷ Height² (m)
BSA (Mosteller)
BSA = √(Height cm × Weight kg ÷ 3600)
IBW Male (Devine)
IBW = 50 + 2.3 × (Height in − 60)
IBW Female (Devine)
IBW = 45.5 + 2.3 × (Height in − 60)
Adjusted Body Weight
ABW = IBW + 0.4 × (Actual − IBW)
Mean Arterial Pressure
MAP = (Systolic + 2 × Diastolic) ÷ 3

🫘 Renal Formulas

CrCl (Cockcroft-Gault)
CrCl = [(140−age) × wt × 0.85*] ÷ (72 × SCr)
*females only
eGFR (MDRD)
175 × SCr⁻¹·¹⁵⁴ × Age⁻⁰·²⁰³ × 0.742* × 1.212**
*female **Black
Parkland Formula
Total 24hr = 4 × Weight (kg) × %TBSA
½ in first 8hrs, ½ in next 16hrs
Fluid Balance
Balance = Total Intake − Total Output

🔬 Normal Lab Values

Lab TestNormal RangeUnits
pH (arterial)7.35 – 7.45
PaCO₂35 – 45mmHg
PaO₂80 – 100mmHg
HCO₃⁻22 – 26mEq/L
Sodium (Na⁺)135 – 145mEq/L
Potassium (K⁺)3.5 – 5.0mEq/L
Chloride (Cl⁻)98 – 106mEq/L
Bicarbonate (HCO₃⁻)22 – 29mEq/L
Glucose (fasting)70 – 99mg/dL
BUN7 – 20mg/dL
Creatinine (male)0.7 – 1.3mg/dL
Creatinine (female)0.5 – 1.1mg/dL
Haemoglobin (male)13.5 – 17.5g/dL
Haemoglobin (female)12.0 – 15.5g/dL
WBC4,500 – 11,000/μL
Platelets150,000 – 400,000/μL
INR (therapeutic)2.0 – 3.0

🔄 Unit Conversions

Weight
1 kg = 2.20462 lb
1 lb = 0.45359 kg
1 stone = 6.35029 kg
Length
1 inch = 2.54 cm
1 foot = 30.48 cm
1 m = 100 cm = 39.37 in
Drug Mass
1 g = 1,000 mg
1 mg = 1,000 mcg
1 mcg = 1,000 ng
Temperature
°F = (°C × 9/5) + 32
°C = (°F − 32) × 5/9
K = °C + 273.15
Volume
1 L = 1,000 mL
1 mL = 1 cc
1 tablespoon = 15 mL
1 teaspoon = 5 mL
Blood Sugar
mmol/L = mg/dL ÷ 18.016
mg/dL = mmol/L × 18.016

📋 Quick Clinical Reference

Normal Vital Signs (Adult)
BP: 90–120 / 60–80 mmHg
HR: 60–100 bpm
RR: 12–20 breaths/min
Temp: 36.1–37.2°C (97–99°F)
SpO₂: ≥ 95%
Urine Output Targets
Adult: 0.5–1.0 mL/kg/hr
(≈ 30–50 mL/hr for 70 kg adult)
Child: 1.0 mL/kg/hr
Infant: 2.0 mL/kg/hr
MAP Targets
Normal: 70–100 mmHg
Minimum perfusion: ≥ 60 mmHg
Sepsis target: ≥ 65 mmHg
GCS (Glasgow Coma Scale)
Eyes: 1–4 · Verbal: 1–5 · Motor: 1–6
Max: 15 (normal)
Intubation indicated: ≤ 8
Severe TBI: ≤ 8

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This cheat sheet is for educational reference only. Always use current institutional drug references and consult with pharmacists or physicians for clinical decisions.