What is the Toothpaste Calculator?
The Toothpaste Calculator estimates how long a single tube of toothpaste will last, given how many people use it, how often they brush, and how much paste they squeeze out each time. It's handy for budgeting, stocking up, or settling debates about who's using too much toothpaste.
How to use it
Enter four values: the tube size in grams (printed on most tubes, often shown in mL or oz — 1 mL ≈ 1 g), the number of people sharing the tube, the average number of brushes per person per day, and the amount of toothpaste used per brushing in grams. Dentists recommend a pea-sized amount of about 0.25 g for adults, though most people use closer to 0.75–1 g (a full strip across the brush).
The formula explained
The calculator multiplies people × brushes per day × grams per use to find total daily consumption, then divides the tube's grams by that figure:
$$\text{Days} = \frac{\text{Tube Size (g)}}{\text{People} \times \text{Brushes/Day} \times \text{Grams/Use}}$$
Weeks and months are simply the days divided by 7 and by 30.44 (the average days in a month).
Worked example
A 100 g tube shared by 2 people, each brushing twice a day, using 0.75 g per brush: daily use = \(2 \times 2 \times 0.75 = 3\) g. $$\text{Days} = 100 \div 3 \approx 33.3 \text{ days}$$ or about 4.8 weeks (just over a month).
FAQ
How many grams is a pea-sized amount? Roughly 0.25 g. A full strip across the brush head is closer to 0.75–1 g.
My tube is in mL or fl oz — what do I enter? Toothpaste is dense, so 1 mL ≈ 1 g works well. For ounces, 1 fl oz ≈ 28 g.
Is this exact? It's an estimate. Real usage varies with technique and how much you can squeeze from a "finished" tube, so treat the result as a planning guide.
