Liquid Dosage Calculator
Enter your bottle size, dose amount, and daily use to see how long your medicine will last, or convert between mg, ml, drops, and teaspoons.
Estimate How Long Your Bottle Will Last
A simple daily-use calculator for liquid medicine, eye drops, cough syrup, and other bottle-based doses.
Use This Tool for Everyday Liquid Medicines
This calculator works well for syrups, eye drops, oral suspensions, and other bottles where you want a simple day estimate.
Enter bottle size
Add the full amount in the bottle, such as 10 mL, 1 fl oz, or 1 cup.
Enter each dose
Type how much you use each time, like 1 mL, 2 drops, or 1 tsp.
Add times per day
Tell the calculator how often you use it each day so it can estimate daily usage.
See days remaining
You will instantly see how many days the bottle should last and the expected finish date.
Liquid Medicine Unit Conversions
Quick reference for converting between mg, mL, drops, teaspoons, and other common liquid medication units.
Converting mg to mL
Milligrams (mg) measure the amount of medication, while milliliters (mL) measure liquid volume. To convert mg to mL, you need the concentration printed on the medicine label, usually written as "mg per mL" (for example, "250 mg/5 mL").
Formula: Volume (mL) = Dose (mg) ÷ Concentration (mg per mL)
Example: If a liquid medicine is labeled 250 mg per 5 mL and a dose of 500 mg is needed, divide 500 mg by the concentration (250 mg ÷ 5 mL = 50 mg/mL), then 500 mg ÷ 50 mg/mL = 10 mL.
Concentration varies by medication and brand, so always use the value printed on your specific bottle or confirm it with your pharmacist before measuring a dose.
Converting Drops to mL
Eye drops, ear drops, and some liquid medications are dosed in drops, but bottle sizes are usually labeled in mL. Drop size varies by dropper and liquid, but a common estimate is about 20 drops per mL.
The calculator above includes a drop-conversion selector (15, 20, 25, or 30 drops per mL) so you can match your dropper's actual size if it's listed on the packaging, and get a more accurate days-remaining estimate.
Teaspoon, Tablespoon & mL Reference Table
| Unit | Approximate mL Equivalent |
|---|---|
| 1 drop | ≈ 0.05 mL |
| 1 teaspoon (tsp) | ≈ 4.93 mL |
| 1 tablespoon (tbsp) | ≈ 14.79 mL |
| 1 fluid ounce (fl oz) | ≈ 29.57 mL |
| 1 cup | ≈ 236.59 mL |
These are standard volume conversions. The calculator above uses these same values, so you can mix units (for example, a bottle measured in mL with a dose measured in teaspoons) and still get an accurate result.
Looking for your next prescription pickup date instead? Try the prescription refill date calculator to estimate when a tablet or liquid prescription will need to be refilled.
Common Questions About Liquid Medicine Usage
Short answers to the questions people usually ask before calculating bottle duration.
Enter the bottle amount, your drops per use, and how many times you use them per day. The calculator estimates how many days the bottle should last based on total daily use.
It depends on the bottle size and how much you take each day. This tool multiplies your dose by your daily frequency and then divides the bottle size by that amount.
Yes. Choose drops as the unit for your bottle size or your dose, then enter how many times per day you use it. The calculator will convert everything into a daily estimate.
If you miss doses often, the bottle may last longer than the estimate shown here. The result assumes you take the medicine exactly as entered every day.