Toothpaste Usage & Cost Calculator

If you brush your teeth twice a day, every single day (and we hope you do), you're bound to go through toothpaste faster than you'd think—especially in a household. This calculator is here to help you estimate how long your toothpaste will last and how much it costs you per month or week.

To get your result, you'll need to enter the following values:

• Toothpaste capacity: This is the volume of the tube, usually written on the packaging in milliliters (ml) or fluid ounces (fl oz). It represents how much paste you get in one purchase.
• Wastage: No matter how carefully you squeeze, there’s always a bit of paste that refuses to come out. This value estimates what percentage of the toothpaste is wasted and not used.
• Pea-sizes of toothpaste per wash: A single brushing session should use a pea-sized amount—about 0.25 ml. Some people use more, so feel free to adjust based on your typical amount.
• Daily brushes per person: How many times each person brushes per day. Most people brush once or twice daily.
• People in the household: Enter how many people use the same tube of toothpaste. This helps estimate how quickly the tube will be consumed.
• Durability unit: Choose how you want to view the result—whether in months, weeks, or days.
• Toothpaste price: The cost of one tube. This allows the calculator to figure out your total and per-time-period costs.

Once you enter these details, the calculator will tell you:

• How long the toothpaste will last based on your inputs.
• How much you're spending on toothpaste per selected time unit (e.g., per month).
• Use this tool to plan your household purchases better, reduce unexpected runs to the store, or even compare different brands and sizes more effectively.

This calculator follows a step-by-step logic to help you estimate how long your toothpaste will last and how much it costs you over time. Here’s a full breakdown of the process:

1. Daily Usage (Base Consumption)

This is the starting point—how much toothpaste your household consumes per day.

Formula:

Daily Usage = Pea-size × Brushes per person × Number of people

A standard “pea-size” of toothpaste is about 0.25 ml

If each person brushes twice a day, they use 0.5 ml/day

Multiply that by the number of people using the toothpaste

Example:

Let’s say:

Pea-size = 0.25 ml

2 brushes per person

3 people in the household

Then:
0.25 × 2 × 3 = 1.5 ml of toothpaste used per day

2. Adjust for Wastage

Not all toothpaste gets used — some gets stuck in the tube, especially near the end. This step accounts for that loss.

Formula:

Adjusted Daily Usage = Daily Usage ÷ (1 – Wastage%)

If wastage is 5%, you’re only using 95% of the tube’s content. So, you need to divide your usage by 0.95 to know the real rate.

Example:

Daily usage = 1.5 ml
Wastage = 5% (or 0.05)
Adjusted = 1.5 ÷ (1 – 0.05) = 1.5 ÷ 0.95 ≈ 1.58 ml/day

This means you effectively “consume” 1.58 ml/day from the toothpaste due to unavoidable wastage.

3. Durability

Now that we know how much toothpaste is effectively used each day, we can calculate how many days the entire tube will last.

Formula:

Durability (in days) = Toothpaste Capacity ÷ Adjusted Daily Usage

Example:

Toothpaste Capacity = 100 ml
Adjusted Usage = 1.58 ml/day
Durability = 100 ÷ 1.58 ≈ 63.29 days

So, your toothpaste will last for about 63 days before you need a new one.

4. Total Cost Per Time Unit

This is where you translate the durability into real cost per chosen time unit (like per month, per week, etc.). You’re essentially calculating how much the toothpaste “costs” you per period.

Formula:

Cost per unit = Price ÷ (Durability ÷ Unit factor)

Where:

Price = how much you paid for the toothpaste

Durability = how long it lasts (in days)

Unit factor = number of days in your chosen time unit

For months: ~30.5 days

For weeks: 7 days

For years: 365 days

Example:

Toothpaste lasts = 63.29 days
Tube price = $3
Selected unit = month (30.5 days)

Cost per month = 3 ÷ (63.29 ÷ 30.5) = 3 ÷ 2.075 ≈ $1.45/month

So, this toothpaste costs your household about $1.45 per month.

Summary

• You calculate how much toothpaste is used daily, considering how many people brush and how often.
• You adjust that amount to include paste wasted in the tube.
• You check how many days your tube will last at that usage rate.
• You divide the cost of the tube by how many “time units” (months/weeks) it will last, to get the cost per unit.

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