Toothpaste Calculator

Plan toothpaste smarter with live cost per brush tube days fluoride dose and refill reminders. Pick smear or pea size add people and brushes per day and see exactly how long each tube lasts with clear guidance for kids and adults plus quick CSV and PDF export. No signup mobile friendly simple and accurate.

Inputs

Live results update as you type

Currency symbol

Use your local currency symbol.

Tube size

If in ml, density converts to grams.

Tube price

Density (g/ml)

Default 1.30. Adjust if your paste is thinner/thicker.

Fluoride (ppm)

Used to estimate fluoride per brush: mg = grams × ppm / 1000.

RDA (abrasivity)

RDA ≤ 250 is within ADA Seal criteria.

Household profiles

Group	People	Brushes/day/person	Grams per brush

Tip: smear/rice-size ≈ 0.10 g, pea-size ≈ 0.25 g.

Visual dose changes with grams/brush

Per‑group fluoride estimate

Group	Grams/brush	Fluoride ppm	Fluoride mg/brush

Formula: mg fluoride = grams per brush × (ppm / 1000).

Summary

Transparent math

Total brushes/day: 0
Daily grams used: 0.00 g
Tube mass: 0 g
Days per tube: 0
Cost per brush: $0.00
Monthly cost: $0.00
Fluoride mg/avg brush: 0.00 mg
RDA check: —

Disclaimer: values are illustrative. For personal dental guidance, consult your dentist.

How this calculator works

We estimate household toothpaste usage based on your profile rows. Each row has a group name, the number of people, how many times each person brushes per day, and grams of paste used per brush. We multiply people × brushes × grams to get daily grams for that row, then sum across rows for the household daily grams. If your tube size is given in milliliters, we convert to grams using density (default 1.30 g/ml), then compute how long the tube lasts by dividing tube grams by daily grams. Cost per brush uses the price divided by total number of brushes per tube.

Quantity	Formula
Daily grams (household)	`∑(people × brushes/day × grams/brush)`
Tube grams	`(unit == g) ? size : size × density`
Days per tube	`tube_grams / daily_grams`
Brushes per tube	`tube_grams / avg_grams_per_brush`
Cost per brush	`price / brushes_per_tube`
Fluoride mg/brush	`grams_per_brush × (ppm/1000)`

Helpful suggestions

Smear/rice-size ≈ 0.1 g and pea-size ≈ 0.25 g; you can edit grams per brush to match your routine.
RDA ≤ 250 is within ADA Seal criteria; higher RDA means more abrasive relative to reference dentin.
Results are averaged across rows; see the per‑group table for mg fluoride per brush.
Use the Copy shareable link to save your setup or send to family.

Deep‑dive: formulas, assumptions & worked example

This section explains exactly how the Toothpaste Calculator turns your inputs into clear, practical outputs. The goal is to make the math transparent so you can tune the assumptions to real household behavior. The calculator models your family as one or more profiles (e.g., adults, children, a specific person). Each profile has four inputs: number of people, average brushes per day per person, and grams of paste used per brush, plus a label. The app multiplies these fields for each profile and then sums them to get the household totals. If your tube size is provided in milliliters, we convert to grams using density (default 1.30 g/ml, which you can adjust). With tube grams and daily grams known, we can compute days per tube, brushes per tube, and all cost metrics.

The fluoride estimate uses a straightforward relationship between concentration (in ppm, or mg per kg) and mass used per brush. Because 1 ppm equals 1 mg of fluoride per kilogram of paste, the dose per brush in milligrams is grams_per_brush × (ppm / 1000). This is a geometric property of the units, not a health directive. The value is shown per profile in the table above and averaged across the whole household in the summary card.

Quantity	Symbol	Formula
Daily grams per profile	`G_p`	`people × brushes/day × grams/brush`
Household daily grams	`G`	`∑ G_p`
Tube grams	`T_g`	`size_g` or `size_ml × density`
Days per tube	`D`	`T_g / G`
Brushes per tube	`B`	`T_g / avg_grams_per_brush`
Cost per brush	`C_b`	`price / B`
Monthly cost	`C_m`	`C_b × (total_brushes/day) × 30`
Fluoride per brush	`F_b`	`grams/brush × (ppm/1000)`

Worked example (2 adults, 1 child 3–6)
Tube size & unit	`100 g`
Price	`$4.99`
Fluoride	`1450 ppm`
Profiles	Adult ×2: 2 brushes/day, 0.25 g; Child ×1: 2 brushes/day, 0.10 g
Total brushes/day	`(2×2) + (1×2) = 6`
Daily grams	`(2×2×0.25) + (1×2×0.10) = 1.20 g`
Days per tube	`100 ÷ 1.20 ≈ 83.3 days`
Avg grams/brush	`1.20 ÷ 6 = 0.20 g`
Brushes per tube	`100 ÷ 0.20 = 500`
Cost per brush	`$4.99 ÷ 500 = $0.00998 ≈ $0.010`
Monthly cost	`$0.010 × 6 × 30 ≈ $1.80`
Fluoride mg/avg brush	`0.20 × (1450 / 1000) = 0.290 mg`

A few practical notes improve accuracy. First, grams per brush drive everything: try weighing a typical pea on a kitchen scale or roughly calibrate using the blue bar visual—smear is around 0.10 g and a pea around 0.25 g. Second, milliliter tubes vary in density by formulation; if your paste is runnier or extremely thick, nudge the density until the results match your lived experience (e.g., how long the last tube actually lasted). Third, cost per brush is most meaningful when comparing brands or sizes; the Compare two tubes approach is to duplicate your setup in another tab and change only the product details.

Edge cases and guardrails: if total daily grams is zero (for example, all grams/brush are blank), days per tube and cost per brush resolve to zero by design. If you model a high number of people without updating grams/brush, your days per tube can shrink quickly; scan the summary and adjust rows. The RDA flag is an informational check based on common criteria for abrasivity; it does not rank medical suitability. Always prioritize your dentist’s recommendations for age‑appropriate amounts, product choice, and technique.