Calculating Days Supply

The days supply calculation is one you will be making for each and every prescription you fill as a pharmacy technician.

In most cases, “Days Supply” is calculated by dividing the maximum amount of the medication used in 1 day by the dispensed amount.

“Days Supply” means just what it sounds like: it is how many days the supply of dispensed medication will last.

Here are a couple of examples:

Example #1

Motrin (ibuprofen) 800mg, 1 tablet 3 times daily as needed, #30.

Days supply takes the maximum amount the patient could take in 1 day, in this case 3 tablets, divided into the amount dispensed of 30 pills-

30/3=10 days supply.

Example #2

Toradol (ketorolac) 10mg, 1 tablet every 4-6 hours as needed, not more than 4 per day. #80.

Quantity of pills: 80 divided by 4 (maximum amount per day) = 20 days supply.

Example #3

Celexa (citalopram) 40mg, 1 tablet daily, #30.

30/1=30 days supply.

These previous examples seem straightforward, but it gets a bit more complicated when you are dealing with other types of prescriptions.

Calculating Ear Drop and Eye Drop Days Supply are different than the example problems above.

Usually with ear and eye drops, 1ml (1 milliliter) will have 15 drops of medication.

Time for another example.

Example #4

Tobramycin Eye Suspension, 1 drop into each eye 3 times daily, 5ml bottle.

1 drop into each eye=2 drops X 3 times daily = 6 drops per day.

5ml X 15 drops per mL = 75 drops total.

75 drops / 6 drops per day = 12.5

Note: In this case the days supply is not a round number. Most pharmacy computer systems are unable to take a decimal number like 12.5. In this case you should round the number down to the nearest round number. So the answer to this example would be 12 days supply.

Topicals: Creams, and Ointments, Gels, 

These dosage forms require the pharmacy tech to calculate days supply using Fingertip Units. One fingertip unit = quantity of topical ointment/cream that when squeezed from a tube, reaches from the tip of an adult finger to the distal, or first crease of the index finger. One FTU is approximately 0.5g of the product.

Liquids: Solutions, Suspensions, Syrups

Example #5

Robutussin AC Syrup:

Take 1 Teaspoonful Every 6 Hours As Needed for Cough, 4oz.

In this example, you need to be able to convert Ounces (the American Standard System of Measurement) to Milliliters (the Metric System of Measurement.)

There are 30 ML in 1 Oz., so 4 Oz = 120 ML. There are 5ML’s in 1 Teaspoonful.

The maximum the patient could take in one day is 5ML times 4 (24 hours in 1 day, divided by 6 = 4) = 20ml used in one day. 120ML divided by 20ML = 6 Days Supply

Hopefully these examples have helped you to understand how to calculate days supply.

Days Supply Questions Answered

Have you got a Days Supply question that you just can't figure out? Submit your question below and/or scroll down for all questions and answers.

What Other Visitors Have Said

Click below to see contributions from other visitors to this page...

250mg/5mL Dispense 200mL Sig: 5mL q.i.d 
How do you set this up to solve to find the days supply?

Days Supply Question: Neurontin 300mg 1 tablet po every other day #15 
Neurontin 300 mg tablets #15 1 tab po qod What is the days supply?

Days Supply/Quantity for Stavudine (Zerit) prescription 
Your pharmacy stocks stavudine in bottles of 30 capsules. How many capsules would you need to dispense for a 90 day supply?

What is the days supply on Advair 250/50 #1 1 puff q12h? 
What is the days supply on advair 250/50 #1 - 1 puff q12h?

Days Supply Question: Norco, #35 pills, 1 tablet every 4-6 hours  
How many days should 35 Norco last me if I was given #35 at 1 every 4-6 hours?

Days Supply Question - #60 pills: Take 2 & 1/2 tablets daily 
If I had 60 pills on my rx, and I take 2 and 1/2 tablets daily, how long will the prescription last me (day supply)?

Days Supply Question - Take One Tablet by Mouth Every 4 Hours As Needed for Pain Not To Exceed 6 Per Day 
How many tablets should I be prescribed for a 30-days supply? For Hydrocodone/ Acetaminophen 10mg-325mg? If I was prescribed a smaller amount is the physician …

How To Figure Out The Days Supply On A TAPER 
David, could you please help me with this TAPER? How do you figure out the Days Supply on it? Maybe I'm making it more complicated than it is, but I don't …

Days Supply Math Question: How Many Additional Tablets Are Needed?  
10 days supply: dosage 2 tablets 3x per day. 16 tablets per bottle. How many additional tablets are needed?

Days Supply Question - #20 pills, 1.5 tablets by mouth daily 
If you have 20 pills and you take 1.5 a days what's the days supply

90 Capsules: 1 cap twice daily for 1 week then increase 
90 Capsules: 1 cap twice daily for 1 week then increase to 3 capsules twice daily. What is the day supply? How do you figure it out?

Pharmacy Math Question: How many full bottles (10 pills/bottle) and additional tablets needed to fill this prescription? 
How many full bottles and additional tablets needed? If days supply needed is 45 and dosage = 1 tab daily, and there are 10 tablets per bottle. …

Coumadin 5mg 90 day supply 
Take two Coumadin 5mg every other day for 90 days. What is the quantity for 90 day supply?

90 xanax a month, 3 a day. When is the earliest I can pick them up? With last month having 31 days 
I get #90 Xanax (generic: alprazolam) a month, with dosing 3 times daily. Last month had 31 days in it. When is the next time I can pick up my refill? …

Pravachol 40mg-How many doses are a 90-Day Supply? 
Mr. Bob Day receives Pravachol 40 mg po daily to lower his cholesterol levels. How many doses would be dispensed for a 90 day supply?

50 pills: 1 pill by mouth every 6 hours prn. What is days supply? 
50 pills, 1 pill by mouth every 6 hours as needed. How many days will this last?

Days Supply Question on Norco 10mg/325mg: Take Every 8 Hours 
Take every 8 hours. How many days supply is that?

Days Supply Question: Norco 7.5 - Take 1-2 tablets Every 4-6 Hours #40 
Written As: Take 1-2 tabs every 4-6 hours, #40. How many days will this prescription last?

Days Supply Question: 1-2 Capsules every 6-8 hours, #90 
#90. Capsules = 1-2 po every 6-8 hours?

Days Supply Question: Klonipin (clonazepam) Take 2-3 pills Daily, #68? 
Take 2 to 3 pills daily, # of pills given is 68. What is the days supply?

Victoza Days Supply Question 
I had a patient today with a script for victoza 3pak ; 3mg sq daily! I have the worst time figuring I out victoza! It doesn't have to be this particular …

Days Supply Question on Testosterone Cypionate Injection-0.5ml every 2 weeks?  
How would you calculate the day supply for 1/2 ml every two weeks?

Click here to write your own.

What is the day supply of Ferrous Sulfate 75mg/ml drops? 
Take 1.5 ml (22.5mg) by mouth every 12 hours, quantity 50 ml. What is the days supply?

Days Supply Question - Celebrex 200mg, #25 i po qd 
How do I calculate the number of days supply?

Days Supply Question for Liquid Medicine: 120ml, 10ml every 8 hours? 
4 ounces = 120ml: Take/Give 10ml every 8 hours. How many days supply is that?

How do you figure the days supply for a liquid (syrup) medication? 
120ML: 10ml every 8 hours-How many days supply is that?

Day Supply Question: 3/4 tablet every 6 hours-#35 
3/4 of a tablet every 6 hours with #35 quantity is how many days worth?

Diphenhydramine Liquid Days Supply Question 
You have received a prescription for diphenhydramine 12.5 mg/5 ml, dispense 240 ml. The patient is to take 50 mg po tid. What is the day's supply for this …

Cough Syrup: 240ml, Take 10 ml every 4 hours-What is Days Supply? 
If your cough syrup has 240 ml and you take 10ml at a rate of every 4 hours, how soon will it run out? and/or how long would it be until when you are able …

Days Supply Question with Coumadin (warfarin) half-tabs and whole tabs  
Coumadin: Take one-half tablet on sun, mon, thur, fri, and sat., then take 1 tab tues and wed. Quantity is 90 tabs/ so what would be your days' supply? …

What is the Days Supply for "1 TSP PO BID", 240ML? 
Give 1 tsp PO bid Disp: 240ml What is the days’ supply of this suspension?

Days Supply Question: Do we always round down when after figuring the Days Supply, the answer includes a fraction? 
When the days supply is calculated and the answer is a fraction do I always round down? Example SIG: Take 1-2 tabs by mouth every 4-6 hours as needed …

Days Supply on 1/2 Tablet Three Times Weekly, #20? 
How do you find a day supply of a prescription of 1/2 tablet 3 times a week (Monday, Wednesday, and Friday) with a quantity of 20?

Liquid Motrin/Ibuprofen Days Supply/Dosing Question 
Take 1/4 oz of Motrin 4 times a day for 5 days. There are 6oz in the stock bottle. How many doses are in the bottle?

Other Ways to Calculate Days Supply And Quantity???? 
I have a test tomorrow for a data entry tech but I'm getting confused with it because everyone asks how I got my answer or why I did my calculations this …

Days Supply Question when Insurance has a 21 day dispensing limitation 
Sig on prescription: take 1 tablet 3 times a day. how do I calculate the maximum quantity allowed if the 3rd party plan has a 21 day dispensing limitation …

Liquid Days Supply Question: Can You Solve This? 
The directions on a prescription read " 1 tbsp QID, ac and hs." The quantity to be dispensed for a 30 day supply is...

Day Supply Question: When figuring Days Supply, does the calculation include the day it is filled? Not rated yet
Does the day supply calculation include the first day a prescription is filled?

Days Supply on Byetta and Symlin (Injectables): Is it always a 30 Days Supply? Not rated yet
what is the day supply on Byetta and Symlin the injectables for diabetes is it always 30 days supply

Click here to write your own.

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