Dentists recommend a pea-sized amount of toothpaste (about 0.25 g) for children and a little more for adults, twice a day. Many adults use a full strip along the brush – three or four times as much as needed – which makes tubes run out quickly.
How to use the Toothpaste Calculator
- Tube size
- Amount per brushing (pea-sized portions)
- Brushes per day
- People
- Wastage
- Price per tube
Results update as you type, and every field accepts the units shown in its menu.
How it works
Enter the tube size, the amount per brushing in pea-sized portions, brushes per day, people, wastage and the price per tube.
Tips
- Use the amounts printed on the product (ml, sheets, applications) where available.
- Count everyone in the household who shares the product.
- Buy a little extra so you never run out unexpectedly.
- Small daily habits add up – check the yearly figures for the real impact.
Common mistakes to avoid
- Forgetting that hot water costs energy as well as water.
- Underestimating how much sunscreen a full application needs.
- Comparing pack prices without checking the size of each pack.
Inputs explained
| Field | What to enter |
|---|---|
| Tube size | Units: mL, fl oz |
| Amount per brushing (pea-sized portions) | A number |
| Brushes per day | A number |
| People | A number |
| Wastage | In % |
| Price per tube | Amount in your currency |
What each result means
- Toothpaste used per day = [People]×[Brushes per day]×[Amount per brushing (pea-sized portions)]×0.25e-6×(1 + [Wastage]÷100)
- Days per tube = [Tube size]÷[Toothpaste used per day]
- Tubes per year = 365.25÷[Days per tube]
- Cost per year = [Tubes per year]×[Price per tube]
Example values
How the main result changes when Tube size changes and everything else stays at the example values above:
| Tube size (mL) | Days per tube |
|---|---|
| 50 | 23 |
| 75 | 34 |
| 100 | 45 |
| 125 | 57 |
| 150 | 68 |
| 200 | 91 |
Formula
Use per day = people × brushes per day × amount per brush (pea-sized ≈ 0.25 mL) × (1 + waste)Days per tube = tube volume ÷ daily useCost per year = tube price × 365.25 ÷ days per tubeWorked example
Inputs — Tube size: 100 mL; Amount per brushing (pea-sized portions): 2; Brushes per day: 2; People: 2; Wastage: 10 %; Price per tube: $4.
Results — Toothpaste used per day = 2.2 mL; Days per tube = 45; Tubes per year = 8; Cost per year = $32.14.
Frequently asked questions
How much toothpaste should I use?
A pea-sized amount for children over three and adults; a smear the size of a rice grain for younger children.
How long does a 100 mL tube last?
For two people brushing twice a day with two pea-sized portions, about 45 days.
Does more toothpaste clean better?
No – brushing technique and fluoride matter, not the amount.
What formula does the Toothpaste Calculator use?
Use per day = people × brushes per day × amount per brush (pea-sized ≈ 0.25 mL) × (1 + waste).