Free calculator
Pill splitter calculator
How much medicine is in half, a third or three quarters of a tablet, whether your tablet is one that may be split, and how many tablets a refill needs.
This does the arithmetic only. The amount you take is the one on your prescription. Split a tablet only when the leaflet, your prescriber or your pharmacist says it may be split.
How much is in part of a tablet?
Enter the strength printed on the box, then pick the part of the tablet.
½ of a 500 mg tablet
250 mg
a half = 50% of the tablet
Which part of the tablet is the amount on my prescription?
For checking a prescription you already have, for example "125 mg" when the box holds 500 mg tablets.
From 500 mg tablets that is
0.25 tablets
That is a quarter of a tablet. Ask your pharmacist whether this tablet may be split.
Can this tablet be split?
Tick what is true for your tablet. Check the box, the leaflet, or ask the pharmacist who dispensed it.
Tick the boxes that apply. If you are not sure, the pharmacist who dispensed the medicine can tell you in a minute.
How many tablets do I need?
For planning a refill: the tablets your prescription uses over a number of days.
Tablets needed
30
Parts of a tablet at a glance
For a few common strengths. Find the strength printed on your box in the left column.
| Whole tablet | ½ | ¼ | ¾ | ⅓ | ⅔ |
|---|---|---|---|---|---|
| 5 mg | 2.5 mg | 1.25 mg | 3.75 mg | 1.67 mg | 3.33 mg |
| 10 mg | 5 mg | 2.5 mg | 7.5 mg | 3.33 mg | 6.67 mg |
| 20 mg | 10 mg | 5 mg | 15 mg | 6.67 mg | 13.33 mg |
| 25 mg | 12.5 mg | 6.25 mg | 18.75 mg | 8.33 mg | 16.67 mg |
| 50 mg | 25 mg | 12.5 mg | 37.5 mg | 16.67 mg | 33.33 mg |
| 100 mg | 50 mg | 25 mg | 75 mg | 33.33 mg | 66.67 mg |
| 250 mg | 125 mg | 62.5 mg | 187.5 mg | 83.33 mg | 166.67 mg |
| 500 mg | 250 mg | 125 mg | 375 mg | 166.67 mg | 333.33 mg |
| 1000 mg | 500 mg | 250 mg | 750 mg | 333.33 mg | 666.67 mg |
Thirds are shown for the arithmetic only: tablets cannot be split into thirds accurately.
Read the box first
The strength is per whole tablet, for example "500 mg film-coated tablets". Letters after the name (ER, XR, SR, EC) matter: those tablets are usually not split.
Use a tablet splitter
A pharmacy splitter cuts along the score line far more evenly than a knife. Keep the other half in its own container and use it for the next dose.
Ask when unsure
The pharmacist who dispensed the medicine can tell you in a minute whether it may be split, and whether another strength or a liquid would be easier.
Questions people ask
▸What does ½ tablet mean on a prescription?
Half of one tablet. If the box says 500 mg, half a tablet holds 250 mg. Your pharmacist can check that this tablet is one that may be split.
▸How much is ⅓ or ⅔ of a tablet?
A third is the tablet's strength divided by 3; two thirds is that amount twice. Tablets cannot be cut into thirds accurately, so a prescription that needs a third usually calls for a different strength or a liquid. Ask the pharmacist.
▸How much is ¼ or ¾ of a tablet?
A quarter is the strength divided by 4, three quarters is that amount three times. Quartering only works on tablets made for it, usually with a cross-shaped score.
▸Can I split a capsule?
Usually not. Capsules hold a measured amount of powder or beads and cannot be divided evenly; some must never be opened. If a capsule dose is hard to manage, ask the pharmacist about other forms.
▸Which tablets should never be split?
Extended- or modified-release tablets (ER, XR, XL, SR, CR, LA), enteric-coated or delayed-release tablets, tablets that dissolve in the mouth, and some hormone or cancer medicines. Splitting them can release too much at once or stop them working.
▸How do I split a tablet evenly?
Use a tablet splitter from a pharmacy, put the tablet in with the score line under the blade, and press once. Split one tablet at a time and use the other half for the next dose.
Not sure what your prescription says?
Words like BID and TID, PRN or extended-release are explained in plain language, and every common medicine has its own page.