Patient on five medications is asking which one 'costs the most' — not because of the co-payment, but the actual daily cost. You need the number to counsel them meaningfully before they consider stopping one.
Daily units = Dose per admin × Doses per day
Days per pack = Pack qty ÷ Daily units
Cost per day = Pack price ÷ Days per pack
Example: $22.50 pack · 30 tablets · 1 tablet ODDays per pack = 30 · Cost per day = $0.75 · Per year = $273.75
1 What this calculator does
Calculates the daily cost of a medication from the pack price (full cost), the number of tablets or dose units in the pack, the dose per administration, and the dosing frequency. Allows comparison of two medications side-by-side for patient counselling.
2 Formula & professional reasoning
Cost per dose = Pack price ÷ Pack quantity
Doses per day = Dose per admin × Doses per day count
Cost per day = Cost per dose × Doses per day
Pack price and days supply are not directly comparable between products because pack sizes vary dramatically. A $28.50 pack of 28 tablets at once daily costs $1.02/day. A $45 pack of 100 tablets at twice daily costs $0.90/day. Cost per day normalises for pack size and dosing frequency, giving the patient and clinician the true ongoing cost of each medication — essential for adherence counselling when cost is a barrier.
3 Worked examples
⚠️ Illustrative example only — not clinical or professional instruction.
Cost/tablet: $22.80 ÷ 30 = $0.76 · Cost/day: $0.76 × 1Cost/tablet: $38.40 ÷ 60 = $0.64 · Cost/day: $0.64 × 2PBS: $7.70 ÷ 30 = $0.26/day · Full price: $28.50 ÷ 30 = $0.95/day4 Sanity check
5 Common errors
| Error | Cause | Consequence | Fix |
|---|---|---|---|
| Using the patient co-payment instead of full pack cost | Using PBS co-payment as pack price | Daily cost vastly underestimated — not meaningful for non-PBS patients | Use the full listed price (ARTG or PBS benefit price) for cost-per-day calculation. The co-payment is the patient's out-of-pocket portion only. |
| Not accounting for dose per administration | Assuming 1 tablet per dose for all medications | Daily cost halved for 2-tablet doses or doubled for 0.5-tablet doses | Check the actual prescription dose — some medications are 2 tablets per dose, or 0.5 tablet |
| Comparing packs with different pack sizes without normalising | Comparing $30/30 tabs vs $50/60 tabs | More expensive-looking pack is actually cheaper per day | Always normalise to cost per day — never compare by pack price alone |
| Not offering PBS registration advice to unregistered eligible patients | Assuming patient already has Medicare/PBS card | Patient paying full price unnecessarily | Check whether the patient holds a Medicare card and is using it. Advise on PBS concession card if they may be eligible. |
6 Reference & regulatory links
7 Professional workflow
Common tools used alongside this one: