2026 NAPLEX Formula Sheet

1 tsp = ? mL

5 mL

1 Tbsp = ? tsp

15 mL

1 fl oz = ? mL

30 mL

1 cup = ? oz = ? mL

1 cup = 8 oz = 240 mL

1 pint = ? oz = ? mL

1 pint = 16 oz = 480 mL

1 quart = ? pints = ? mL

1 quart = 2 pints = 960 mL

1 gallon = ? quarts = ? mL

1 gallon = 4 quarts = 3840 mL

1 kg = ? lbs

2.2 lbs

1 oz = ? grams

28.4 grams

1 lb = ? g = ? oz

1 lb = 454 g = 16 oz

1 grain = ? mg

65 mg

mEq to mmol for monovalent ions

1:1 for monovalent ions

mEq to mmol for divalent ions

1:0.5 for divalent ions

1 inch = ? cm

2.54 cm

1 meter = ? centimeters

100 cm

% w/v

x g/100 mL

% v/v

x mL/100 mL

% w/w

x g/ 100 g

PPM to percentage strength

Move decimal left 4 places

Ex: 2.2 PPM = 0.00022%

Percentage strength to PPM

Move the decimal RIGHT 4 places

Ex: 0.00022% = 2.2 PPM

specific gravity (SG)

SG = weight of substance (g) / weight of equal volume of water (g)'

SG = g/mL

Dilution Formula

Q1 x C1 = Q2 x C2

Q1 = old qty, C1 = old conct.

Q2 - new qty, C2 = new conct.

Alligation Formula

High % X parts High %

Desired

Low % X parts Low %

Osmolarity formula

mOsmol/L = wt of substance (g/L) / MW (g/mole) x (# of particles) x 1000

*Note: must normalize wt to g/L

Isotonicity E-value Equation

E= (58.5)(i) / (MW of drug x 1.8)

mols formula

mols = g/MW

mmols formula

mmols = mg/MW

mEq formula

mEq = mg x valence/MW

OR

mEq = mmol x valence

Enteral Nutrition Calories

Carbs & Protein = 4 kcal/g

Fat = 9 kcal/g

Parenteral Nutrition Calories

Amino Acids = 4 kcal/g

Dextrose = 3.4 kcal/g

Fats:

ILE 10% = 1.1 kcal/mL

ILE 20% = 2 kcal/mL

ILE 30% = 3 kcal/mL

Determining fluid needs when weight > 20 kg

1,500 mL + (20 mL)x(weight in kg - 20)

can estimate using 30-40 mL/kg/day

Total Energy Expenditure (TEE)

TEE = BEE x activity factor x stress factor

Grams of Nitrogen From Protein

Nitrogen (g) = protein intake (g) / 6.25

Corrected Calcium for albumin <3.5 (not needed with ionized Ca)

Ca(Corrected) mg/dL = calcium reported (serum) + [(4.0-albumin) x 0.8]

BMI equation

weight (kg) / height (m^2)

(weight (lbs) / height (in^2) ) x 703

IBW females

45.5 + 2.3 x (inches over 5 feet)

IBW males

50 + 2.3 x (inches over 5 ft)

Adjusted Body Weight (AdjBW) Equation

AdjBW = IBW + 0.4(ABW-IBW)

If patient is underweight which weight do you use?

TBW

If a patient is normal weight or obese for most drugs, use...

TBW

For dosing Acyclovir, Aminophylline, & Levothyroxine use...

IBW

For dosing Theophylline (normal weight/obese) & Aminoglycosides (obese) use...

AdjBW-0.4

Flow Rate/Drop Factor (gtt/min) formula

(# gtts/mL) x (mL/hr) x (hr/60min) = (# gtts/min)

Dehydration ratio

BUN:SCr > 20:1

Cockcroft-Gault formula

(140-Age) x (kgs)

-------------------- X 0.85 (if female)

(72) x (SCr mg/dL)

Acidosis vs Alkalosis

Acidosis: pH < 7.35

Alkalosis: pH > 7.45

Respiratory Acidosis vs. Alkalosis

Acidosis: pCO2 > 45 (high)

Alkalosis: pCO2 < 35 (low)

Metabolic Acidosis vs. Alkalosis

Acidosis: HCO3 > 26 (high)

Alkalosis: HCO3 < 22 (low)

Respiratory Acidosis

LOW pH + HIGH CO2

Respiratory Alkalosis

HIGH pH + LOW CO2

Metabolic Acidosis

LOW pH + LOW HCO3

Metabolic Alkalosis

HIGH pH + HIGH HCO3

Anion gap (AG) formula

AG = Na - Cl - HCO3

weak acid pH formula

pH = pKa + log (salt/acid)

weak base pH formula

pH = pKa + log (base/salt)

percent ionization of a weak acid

100 / (1+10^[pKa-pH])

percent ionization of a weak base

100 / (1 + [10^(pH-pka)]

Absolute Neutrophil Count (ANC) formula

ANC = WBC x [(% segs + % bands)/100]

Farenheit to Celsius

Cº = (Fº - 32)/1.8

Celsius to Farenheit

Fº = (Cº x 1.8) + 32

Time to Burn (TTB) formula [sunscreen]

TBB (w/ sunscreen in min) = SPF x TTB (w/o sunscreen)

Risk Formula (biostatistics)

# of subjects in group with a unfavorable event/ total # of subjects in group

Relative Risk (RR) Formula

risk in treatment group/risk in control group

Relative Risk Reduction (RRR) Formula

(% risk in control group - % risk in treatment group) / % risk in control group

Absolute Risk Reduction (ARR) Formula

% risk in control group - % risk in treatment group

NNT or NNH equation

1/ARR (expressed as a decimal)

NNT = round up

NNH = round down

Incremental Cost-Effectiveness Ratio (ICER)

(cost new - cost old)/(effect new - effect old)

Pack-year smoking history

Cigarette packs/day x years smoked

Initiating Basal-Bolus Insulin in T1DM

1. TDD = 0.5 U/kg/day (TBW)

2. 50% bolus + 50% basal

3. Divide bolus by 3 meals

Insulin to Carbohydrate Ratio: Rule of 450 for regular insulin

g of carbs covered by 1 unit regular insulin = 450/TDD insulin

Insulin to Carbohydrate ratio: Rule of 500 for rapid-acting insulin

g of carbs covered by 1 unit rapid-acting insulin = 500/ TDD insulin

Correction Factor: 1500 rule for regular insulin

1500/TDD = correction factor for 1 unit of regular insulin

Correction Factor: 1800 rule for rapid-acting insulin

1800/TDD = correction factor for 1 unit of rapid-acting insulin

Friedwald equation (LDL)

LDL= TC - HDL - (TG/5)

Do not use if TG > 400

Minimum weighable quantity (MWQ)

sensitivity requirement / acceptable error rate (usually 0.05)

BSA (Mosteller) Equation

square root of [((Ht (cm) x Wt (kg))/ 3600]

Bioavailability (F)

F(%) = 100 x [(AUC extravascular/AUC intravenous) x (DOSE intravenous/DOSE extravascular)]

Volume of distribution (Vd)

Vd = (amount of drug in the body) / (plasma drug concentration)

Clearance (Cl) equation

Cl = [dose x bioavailability (f)] / AUC

Elimination rate constant (Ke)

Ke = Cl/Vd

Predicting drug concentrations

C2 = C1 x e^-kt

or

Ke = ln(C1/C2)/t

Half-life (t1/2)

t1/2 = 0.693/ke

Loading dose (LD)

LD = (Desired concentration x Vd) / F

Mean Arterial Pressure (MAP)

MAP = [(2 x diastolic) + systolic] / 3

Phenytoin (total) correction for Albumin < 3.5

Phenytoin (corrected mcg/mL) = total phenytoin measured / (0.2 x albumin) + 0.1

KCL solution to tablets

KCL 10% = ___mEq/___mL

KCL 10% = 20mEq/15mL

Calcium Carbonate = ? elemental calcium

Calcium Citrate = ? elemental calcium

Carbonate = 40%

Citrate = 21%

Aminophylline to Theophylline conversion

Multiply by 0.8 ATM

Statin equivalent doses

Pitavastatin 2 mg

Rosuvastatin 5 mg

Atorvastatin 10 mg

Simvastatin 20 mg

Lovastatin 40 mg

Pravastatin 40 mg

Fluvastatin 80 mg

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Metoprolol IV:PO conversion

IV:PO = 1:2.5

Loop diuretic equivalent doses

Furosemide 40 mg

Torsemide 20 mg

Bumetanide 1 mg

Ethacrynic acid 50 mg

Furosemide IV:PO

1:2 (IV:PO)

Other loops IV:PO conversion

1:1

Insulin Conversions, usually 1:1

What are the two exceptions?

1. NPH dosed BID -> Glargine dosed QD = use 80% NPH dose

2. Toujeo -> other Glargine forms = use 80% of Toujeo dose

Levothyroxine IV:PO

0.75:1 (IV:PO)

Steroid equivalent doses

Cortisone 25mg

Hydrocortisone 20mg

Prednisone 5mg

Prednisolone 5mg

Methypred 4mg

Triamcinolone 4mg

Dexamethasone 0.75mg

Betamethasone 0.6mg

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Lithium Formulations Equivalent Doses

5 mL lithium citrate syrup = 300 mg lithium carbonate = 8 mEq Li+ ion

Opioid conversion table