Formula

  dose ordered   dose available

x volume available

Actually this is the same formula used in the "PO dosage calculator."

Examples

1)  Dr. Smith has ordered a heparin infusion of 1000 units/hour for John Doe in bed 7.  The infusion is to be mixed as 25,000 units in 500 mL .9% NS.  What rate will the IV pump be set to?  In this example,

1000 units/hr = dose ordered25,000 units = dose available500 mL = volume available

  1,000units  

25,000unitsx 500mL

which = 20 mL

So the volume to give, an infusion, = 20 mL/hour

2)  Give 40mg of Lasix® (furosemide) IVP.  The vial of furosemide contains 100 mg per 10 mL.  In the example,

40 mg = dose ordered100 mg = dose available10 mL = volume available

  40mg   100mg

x 10mL

which = 4 mL

So the volume to give, a 1x dose, = 4 mL

TO CALCULATE RATE USING MINUTES

volume   x   calibration minutes

  =  gtt/min

 

TO CALCULATE RATE USING HOURS

volume   x   calibration hours  x  60

  =  gtt/min

 

Examples

1)  Give a 50cc IVPB over 30 minutes using IV tubing with a calibration of 10.  How many drops per minute should this IVPB be set for?  See the example below.

select "x = minutes"x = 30volume = 50calibration = 10

Actual formula:

50 x   10 30

  =  16.7 or 17 gtt/min

 

2)  Using IV tubing alone (calibrated at 60), prepare an IV to infuse 1 liter over 8 hours.  How many drops per minute should the IV be set for?  See the example below.

select "x = hours"x = 8volume = 1000calibration = 60

Actual formula:

1000ml   x   60 8 x 60

  =  125 gtt/min

Note, when using microdrip tubing (calibration = 60), the drip rate will be the same as mL/hr.  This will save you the time of calculating the drip rate if asked to give the rate in mL/hr.

3)  The doctor orders an IV to infuse at 125cc/hr.  Calculate the flow rate using 10 drop/min IV tubing.

select "x = milliters/hour"x = 125calibration = 10

Actual formula:

125cc x 1060

= 20.8 or 21 gtt/min

Note

You may be wondering why a second answer is displayed in the calculator.  The first answer displays the number of drops per minute.  The second answer displays how many drops fall in 15 seconds.  Sometimes the IV rate is set by counting for 15 seconds instead of a full minute.

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time = hours

time = minutes

time

volume mL

rate mL/hour

Examples

1)  If an order was written to infuse a liter of IV fluid every 8 hours, at what rate would the IV pump be set for? Answer is 125 mL/hour.

Using the calculator, select the time to equal hours (it's already preselected).  Next enter 8 as the value for time (8 hours).  Enter 1000 mL (1 L = 1000 mL) as the volume to be infused.  Click the "solve"

button which calculates the result as 125 mL/hour.  See the example below.

 

2)  You have recieved a new admission from the E.R.  The patient has class IV CHF and the doctor has ordered a loading dose of Inocor®(amrinone lactate).  The loading dose is to be administered over 3 minutes.  Pharmacy has brought the loading dose as a 50 mL IVPB.  At what rate should the IVPB be infused? Answer is 1000 mL/hour.

Using the calculator, select time to equal minutes.  Next, enter 3 as the value for time (3 minutes).  Enter 50 as the volume to be infused.  Click the "solve" button which calculates the result as 1000 mL/hour.  See the example below. 

Formulas

TO CALCULATE RATE USING HOURS

VOLUMEHOURS   = mL/hr

 

TO CALCULATE RATE USING MINUTES

        VOLUME           (MINUTES /

60)  = mL/hr

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dose ordered (mcg)

dose available (mg)

mL available

rate (mL/hr)

Example

Start an infusion of nitroglycerin at 10 mcg/min, then titrate to chest pain.  The nitroglycerin is to be mixed as 50 mg in 250cc of D5W.  Use the example below to see how to plug the numbers into the calculator.

In this example, the nitroglycerine infusion will be set to 3 mL/hr.

Formula

First, convert mcg/min to mg/hr.For example, 10 mcg/min becomes 0.6 mg/hr.

Next, solve the rest by using the IV dosage formula.In the example given, 0.6mg is the dose ordered,

50 mg is the dose available,and 250 mL is the volume available.

If you're lucky enough to have new IV pumps that accept mcg/min, obviously this entire process is unnecessary.

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dose ordered (mcg)

weight (kg or lbs)                             

dose available (mg)

mL available

rate (cc/hr)

Example

Dr. Smith wants a dopamine drip started at 20mcg/kg/min on John Doe in Bed 7.  John Doe's weight is 70 kilograms.  He wants an 800mg vial of dopamine mixed in 500 mL of D5W.  Plug in the amounts in the calculator as shown below.

Click the box to enter weights in pounds

Using the calculator, John Doe's IV pump is set to deliver 53 cc/hr of Dopamine.

Formula

(mcg x kg) X 60

1000

First, convert mcg/kg/min into mg/hr.In the example above, the dose would be 84 mg/hr.

(20mcg x 70kg) X 60 = 84

1000

Next, use the IV dosage formula to solve the rest of the problem.

dose ordered X volume available

dose available

In the example, 84 mg is the dose ordered,800 mg is the dose available,

500 mL is the volume.

84mg X 500ml = 52.5 ml/hr

800mg

 

If you're lucky enough to have new IV pumps that accept mcg/kg/min, obviously this entire process is unnecessary.

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IV pump

No IV pump

enter volume

enter ml/hr

enter gtts/min

enter IV calibration 

hours

minutes

Formulas

Basic Time

VolumeRate

= Hours

Time Calculated Using IV Tubing Only

Volume / (     gtt/min   Calibration

x  60 ) = Hours

Examples

1. Using a volumetric IV pump calculate to duration of 1000 mL of normal saline infusing at 125mL/hour.

select "IV pump"volume = 1000 millilitersrate = 125 mL/hr

Actual formula:

1000mL125

= 8 Hours

2. There are 250 mL of D5W infusing at 33 gtt/min on IV tubing calibrated at 10 gtt/mL.  Calculate the infusion time.

select "No IV pump"volume = 250 mLrate = 33 gtt/mincalibration = 10 gtt/mL

Actual formula:

250 / (   33 gtt/min 10

x  60 ) = 1.26 Hours

0.26 x 60 = 16 minutesSo 1.26 Hours = 1 Hour & 16 minutes

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rate or volume given

dose available

volume available

dose ordered

Example

You have received report on a patient with a heparin drip but the nurse forgot to say what dosage the drip was infusing at.  The heparin bag is labeled 25,000 units in 250 mL NS and the IV pump is infusing at 20 mL/hr.  In this example,

20 mL/hr = rate, an infusion.25,000 units = dosage available250 mL = volume available

So the dosage ordered, an infusion, = 2000 units/hour

See the example below.

Formula

          rate             x dose available

mL available

Using the formula on the example above looks like this:

20cc/hr250mL

x 25,000units

which = 2000 units/hr

It doesn't matter if you use milligrams or units or something else in the formula.

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IV rate mL/hr

dose available

mL available

mcg/min

Example

A patient is on a norepinephrine drip infusing at 56 cc/hr.  There is no titration table table at the bedside.  The IV bag is labeled 32 mg norepinephrine in 500cc Dextrose 5%.  How many mcg/min is the patient receiving?  Use the example below to see how to solve this problem with the calculator.

rate = 56mL/hrdose available = 32mgmL available = 500mL

With the calculator, we see the patient is recieving 60 mcg/min of norepinephrine.  This is a higher than recommended dose!!!

Formula

In this example, first determine how many milligrams/hour is being delivered by the IV pump. The rate of the IV pump (mL/hr) is divided by the volume of the IV bag (mL available), then multiply this result by the total amount of medication (mg) in the IV bag.

          rate             mL available

x dose available

becomes

  56mL/hr  

500mLx 32mg

which = 3.58 mg/hr

Next, after the milligrams/hour has been determined, use the next formula to convert from milligrams/hour to mcg/min.

  mg     60min

x 1000

becomes

  3.58mg  

60minx 1000

which is 59.7 mcg/min (yikes!)

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IV rate cc/hr

weight (kg)

dose available

mL available

mcg/kg/min

Example

You have received a patient from another hospital on a dopamine drip except no information was given about it.  The bag is labeled with the concentration of 800 mg in 500cc of D5W.  The IV pump is infusing at  53 cc/hr and the patient weighs 70kg.  How much dopamine is this patient receiving?  Use the example below to see how this problem was solved.

rate = 53mL/hrweight = 70kgdose available = 800ml available = 500

Using the calculator, we know the patient is receiving 20 mcg/kg/min of dopamine.

Formula

Using the example above, first determine how many milligrams/hour is being delivered by the IV pump. The rate of the IV (cc/hr) is divided by the volume of the IV bag (mL available), then multiply this result by the total amount of medication (mg) in the IV bag.

          rate             mL available

x dose available

becomes

  53mL/hr  

500mLx 800mg

which = 84.8 mg/hr

Next, after the milligrams/hour has been determined, use the next formula to convert from milligrams/hour to mcg/kg/min.

  mg     60min

x 1000 / kg

becomes

84.8mg60min

x 1000 / 70

which = 20.2 mcg/kg/min

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weight (kg)

height (cm)

adult dose

child dose

I want to use a nomogram to determine BSA

Example

The doctor has ordered an antibiotic whose average adult dose is 250 mg per day.  What would the dosage for this medication be on a child who is 100 cm in length and weighs 25 kg?  See the example below.

In this example, 115 mg of medication would be given.

Formula

First, the body surface area (BSA) must be determined:

kg0.425 x cm0.725 x 0.007184 = BSA

The above formula is just one method for determining BSA.  Results with other formulas will vary.

Next, the following formula* is used:

BSA x adult dose = approx. child dose1.73

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weight kg

hours NPO

mL 1st hr

mL 2nd hr

mL 3rd hr

Example

What is the NPO deficit for a patient who weighs 50 kg who has been NPO for 10 hours prior to surgery?  The answer is 1 liter (500 mL 1st hour, 250 mL 2nd hour, and 250 mL 3rd hour).  See how the numbers were used on the calculator below.

Formula

IV fluid replacement for NPO  deficit = 2mL/kg for each hour NPO prior to surgery. 

50% of this deficit is replaced within the first hour of surgery with the remaining 50% being replaced over the next 2 hours.  If the patient stayed in the hospital overnight with an IV infusing while NPO, subtract this amount from the NPO deficit.

In the example above:

2 mL/kg/hr = 2 x 50 x 10 = 1000@1st hr, 500 mL will be replaced2nd hr, 250 mL will be replaced

3rd hr, 2hr 250 mL will be replaced

If in this example, the patient stayed in the hospital overnight with an IV infusion at 100 mL/hr while NPO, all their NPO deficit (1 liter) would already be replaced.

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male

female

weight   

height   

IBW

IBW + 30%

ABW

Formula

IBWEstimated ideal body weight in (kg)Males: IBW = 50 kg + 2.3 kg for each inch over 5 feet.Females: IBW = 45.5 kg + 2.3 kg for each inch over 5 feet.

ABWEstimated adjusted body weight (kg)If the actual body weight is greater than 30% of the calculated IBW, calculate the adjusted body weight (ABW): ABW = IBW + 0.4(actual weight - IBW)

The IBW and ABW are used to calculate medication dosages when the patient is obese.

This formula only applies to persons 60 inches (152 cm) or taller.  If calculating by hand use formula as shown (inches & kilograms).  Formulas referenced from GlobalRPH.

Examples

Example 1

Calculate the ideal body weight (IBW) of a man who is 64 inches tall and weighs 70 kilograms.  If this man is obese (> IBW + 30%), calculate the adjusted body weight.

To solve the example using the calculator, select the radio button for male. Next, enter the height (inches)  and weight (kilograms):

weight = 70 kgheight = 64 inchesIBW = 59.2

Or solve using formula:

IBW = 50 kg + 2.3 x each inch over 5 feet (60inches)IBW = 50 kg + 2.3 x 4 inchesIBW = 50 kg + 9.2IBW = 59.2 kg

The man's actual weight is less than IBW + 30% so it is not necessary to calculate the adjusted body weight (ABW).

Example 2

Calculate the ideal body weight (IBW) of a woman who is 64 inches tall and weighs 80 kilograms.  If this woman is obese (> IBW + 30%), calculate the adjusted body weight.

To solve the example using the calculator, select the radio button for female. Next, enter the height (inches)  and weight (kilograms):

weight = 80 kgheight = 64 inchesIBW = 54.7

Or solve using formula:

IBW = 45.5 kg + 2.3 x each inch over 5 feet (60inches)IBW = 45.5 kg + 2.3 x 4 inchesIBW = 45.5 kg + 9.2IBW = 54.7 kg

The woman's actual weight is greater than the IBW + 30%, so calculate the ABW:

ABW = 54.7 kg + 0.4( 80kg - 54.7 kg)ABW = 54.7 kg + 0.4( 25.3 kg )ABW = 54.7 kg + 10.1kgABW = 64.8 kg

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 pH

 CO2

 HCO3

Normal Arterial Blood Gas Values

pH 7.35-7.45PaCO2 35-45 mm HgPaO2  80-95 mm HgHCO3  22-26 mEq/LO2 Saturation 95-99%BE  +/- 1

Four-Step Guide to ABG Analysis

1. Is the pH normal, acidotic or alkalotic?2. Are the pCO2 or HCO3 abnormal?  Which one appears to

influence the pH?

3. If both the pCO2 and HCO3 are abnormal, the one which deviates most from the norm is most likely causing an abnormal pH. 

4. Check the pO2.  Is the patient hypoxic?

I used Swearingen's handbook (1990) to base the results of this calculator. The book makes the distinction between acute and chronic disorders based on symptoms from identical ABGs. This calculator only differentiates between acute (pH abnormal) and compensated (pH normal). Compensation can be seen when both the PCO2 and HCO3 rise or fall together to maintain a normal pH. Part compensation occurs when the PCO2 and HCO3 rise or fall together but the pH remains abnormal. This indicates a compensatory mechanism attempted to restore a normal pH. I have not put exact limits into the calculator. For example, it will perceive respiratory acidosis as any pH < 7.35 and any CO2 > 45 (i.e. a pH of 1 and CO2 of 1000). These results do not naturally occur.

pH PaCO2 HCO3

Respiratory AcidosisAcute < 7.35 > 45 NormalPartly Compensated

< 7.35 > 45 > 26

Compensated Normal > 45 > 26

Respiratory AlkalosisAcute > 7.45 < 35 NormalPartly Compensated

> 7.45 < 35 < 22

Compensated Normal < 35 < 22

Metabolic AcidosisAcute < 7.35 Normal < 22Partly Compensated

< 7.35 < 35 < 22

Compensated Normal < 35 < 22

Metabolic AlkalosisAcute > 7.45 Normal > 26Partly Compensated

> 7.45 > 45 > 26

Compensated Normal > 45 > 26

Mixed Disorders

It's possible to have more than one disorder influencing blood gas values.  For example ABG's with an alkalemic pH may exhibit respiratory acidosis and metabolic alkalosis.  These disorders are termed complex acid-base or mixed disorders.

*This table is able to classify most clinical blood gas values but not all.  In cases where blood gas values do not fall into any of the above classifications, an answer "unable to determine" will appear when using the interpreter.  For example a pH of 7.428, pCO2 43.6, and a HCO3 of 29.1 do not match any of the classifications (I found these results in someone's chart).  While the pH and pCO2 are normal, the HCO3 is abnormally high.

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convert fahrenheit & celsiusnursing calculators search site map

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enter temperature

convert to Fahrenheit

convert to Celsius

result

solution

Directions  

Enter temperature to be converted in degrees Fahrenheit (°F) or Celsius (°C aka centigrade) in box.  Select either Fahrenheit or Celsius button to perform conversion.  Press "convert" button to display result at bottom.

Formula

°C  x  9/5 + 32 = °F

(°F  -  32)  x  5/9 = °C

Examples

1)  Convert 37°C to Fahrenheit.

37°C x  9/5 + 32 = 98.6°F

OR

37°C x 9 + 32 = 98.6°F 

5

2)  Convert 98.6°F to Celsius.

(98.6°F  -  32)  x  5/9 = 37°C

OR

(98.6°F - 32) x 5 = 37°C 

9

Formulae

cm x 0.39* = in

in = ft

12

in  x  2.54 = cm

Examples

If a woman is 5 foot, 3 inches (5' 3"), what is her height in centimeters?

(5' x 12) + 3" = 63"

63" x 2.54 = 160 cm

 

If a woman is 5 foot, 8 inches (5' 8"), what is her height in centimeters?

(5' x 12) + 8" = 68"

68" x 2.54 = 172.7 cm

If a man is 203.2 centimeters tall, what is his height in feet and inches?

203.2 cm x 0.3937008 = 80"

80 = 6.67' 

12

.67 x 12 = 8.04 remainder

80 = 6 ft and remainder = 8 in

12

OR

6' 8"

Dosage By Weight Questions

Given the weight of a patient and a dosage specified in terms of weight, calculate

the necessary dosage. These problems are a type of pediatric dosage

calculations. 

Formula:

Weight in Kg * Dosage Per Kg = Y (Required Dosage)

Example: A doctor orders 200 mg of Rocephin to be taken by a 15.4 lbinfant

every 8 hours. The medication label shows that 75-150 mg/kg per day is the

appropriate dosage range. Is this doctor's order within the desired range?

Weight in Kg * Dosage Per Kg = Y (Required Dosage)

Convert 15.4 lb to kg.

lb → kg    ( ÷ by 2.2 )

15.4 lb ÷ 2.2 = 7 kg7 kg * 75 mg/kg = 525 mg (Minimum Desired Dosage)

7 kg * 150 mg/kg = 1,050 mg (Maximum Desired Dosage)

24 hours in one day and the medication is ordered every 8 hours.

24 hrs / 8 hrs = 3 times per day doctor ordered medication

200 * 3 = 600 mg ordered per day

600 mg is within the desired range of 525-1,050 mg

Yes doctor has ordered a dosage within the desired range. 

Example: Solumedrol 1.5 mg/kg is ordered for a child weighing 74.8 lb.

Solumedrol is available as 125 mg / 2mL. How many mL must the nurse

administer?

Weight in Kg * Dosage Per Kg = Y (Required Dosage)

Convert 74.8 lb to kg.

lb → kg    ( ÷ by 2.2 )

74.8 lb ÷ 2.2 = 34 kg34 kg * 1.5 mg/kg = 51 mg

This is now an ordinary Mass/Liquid For Liquid Question. 51 mg is ordered

and the medication is available as 125 mg / 2 mL.Ordered

Havex Volume Per Have = Y (Liquid Required)

51 mg

125 mgx 2 mL = 0.82 mL

Fluid Maintenance Requirement Questions

Given the weight of a child or infant, calculate the necessary amount of fluid per

day. Different hospitals may have different policies, but for learning how to

perform these pediatric dosage calculations, the following commonly used table

of fluid requirements may be used. 

Weight Range Required Daily Fluid

0-10 kg 100 mL per kg

10-20 kg 1,000 mL + 50 mL per each kg above 10 kg

20-70 kg 1,500 mL + 20 mL per each kg above 20 kg

Over 70 kg 2,500 mL (adult requirement)

Example: An infant weighs 4 kg. What is the required amount of fluid per day in mL?

0-10 kg 100 mL per kg

4 kg x 100 mL/kg = 400 mL

Example: An infant weighs 30.8 lb. What is the required IV flow rate in mL/hr to

maintain proper fluid levels? 

Convert 30.8 lb to kg.

lb → kg    ( ÷ by 2.2 )

30.8 lb ÷ 2.2 = 14 kg

10-20 kg 1,000 mL + 50 mL per each kg above 10kg

14 kg - 10 kg = 4 kg (There are 4 kg over 10 kg).

1,000 mL + (50 mL/kg x 4 kg) = 1,200 mL/day

This is now an ordinary IV Flow Rate - mL Rate Question. The required

volume is 1,200 mL and the time is one day.Volume (mL)

Time (hr) = Y (Flow Rate in mL/hr)

There are 24 hours in one day.

1 day x 24 = 24 hr1,200 mL

24 hr = 50 mL/hr