Replacement brush head costs: annual average and pack budget

Editorial deskUpdated September 2026Arithmetic, with the formulas and test cases published
Short answer

Enter pack size, pack price, replacement interval and number of users to get two different figures: the long-run average cost of replacing heads, and the whole-pack purchase budget for a 52-week period. The purchase estimate assumes every user starts with a new head bought from these packs and that there is no existing stock.

Those two numbers answer different questions. The average tells you whether a pack is good value per head. The budget tells you what you will actually spend in a year, because packs only come in whole boxes.

Work out the average and the budget

Every value must be a positive number. The calculator will not correct an invalid entry for you; it will return an error instead.

A whole number
The price you pay for one pack
The ADA advises every 3 to 4 months, or sooner if bristles are matted or frayed. That is roughly 13 to 17 weeks, not an exact conversion
Each person has their own head

Round currency for display only. Intermediate values are not rounded.

About this tool and its limits

Purpose: to support one decision, from numbers you supply.
Not suitable for: any medical, legal, safety or warranty decision.
Method type: arithmetic on your inputs, or an editorial rule stated below. It is not a validated model.
Accountable publisher: the editorial desk of this store.
Method version: 1.0. Last checked: 2026-09-14.

The calculation runs in your browser. This tool's own code does not save or transmit your answers. Separate site analytics and other services are described in our privacy policy.

Input What it means Accepted values
Heads per pack Used directly in the calculation. any number, default 4
Price per pack (USD) Used directly in the calculation. any number, default 20
Replacement interval (weeks) Used directly in the calculation. any number, default 13
People using these heads Used directly in the calculation. any number, default 1

Worked example

With the pre-filled values shown above, it returns:

Headline result Check your inputs

Calculation checks

Case Observed behaviour
Boundary input (highest accepted values) $10.00 per person per year (long-run average)
Invalid input (zero values) Check your inputs

These checks show the tool behaves as documented. They do not establish medical or scientific validity.

What this result cannot tell you. It is an estimate derived entirely from the numbers you enter, using the relationships described on this page. It does not measure your situation, it does not account for anything not listed as an input, and it cannot establish which product you should buy. Where the result matters for your health, safety, money or a warranty, treat it as a starting point and check it against the primary source linked at the bottom of this page.

Products and commercial interest. This store sells the products these guides discuss. Product data never changes a calculation. To report a problem, use the contact page and include this page's URL, the inputs you used and the result you expected.

The formulas, in full

Step Formula
Unit price pack price ÷ heads per pack
Long-run average cost per person per year (pack price ÷ heads per pack) × (52 ÷ interval in weeks)
Approximate cost per day annualised cost ÷ 365
Whole heads needed per person ceil(52 ÷ interval in weeks)
Total heads needed users × ceil(52 ÷ interval)
Packs to buy ceil(total heads needed ÷ heads per pack)
Purchase budget packs to buy × pack price
Unused spares (packs to buy × heads per pack) − total heads needed

Test cases, so you can check the arithmetic yourself

Inputs Expected result
7 heads, $21, 16 weeks, 2 people Unit price $3.00. Long-run average 3.25 heads and $9.75 per person per year. 8 whole heads used, 2 packs, purchase budget $42.00, 6 unused spares.
4 heads, $20, 13 weeks, 1 person Unit price $5.00. Long-run average 4.00 heads and $20.00 per person per year. 4 whole heads used, 1 pack, purchase budget $20.00, 0 spare heads.
Interval of 0 Error, with no result. The interval must be greater than zero.
Pack size of 2.5 Error, with no result. Pack size is a whole number of heads.
Negative or blank price Error, with no result. The price must be a positive number.
Why the two figures differA replacement interval rarely divides into 52 weeks exactly, and heads are only sold in whole packs. So the average per head and the amount you actually hand over in a year are different numbers, and the difference grows with more users and smaller packs.

Compare pack contents before comparing prices

Unit price depends on both the pack price and the number of heads. A cheaper pack can cost more per head. Compatibility is a separate question: a low annual cost is irrelevant if the head does not fit your handle. Check the handle models explicitly listed on the product page, and treat anything not stated as unknown rather than assuming it fits.

Product Heads stated in the listing Price checked Handle models explicitly listed
See the brush head range Read from the listing at the time of purchase Prices change. Check the product page. Where the listing names models, treat those as the only confirmed matches
What compatibility we do not establishWe do not infer compatibility from brand name, appearance, connector resemblance or a photograph. If the listing does not name your handle model, compatibility is not stated, and you should confirm with the manufacturer or your dental professional before buying.

Questions people ask

How does pack size change the cost?
It changes the unit price and it changes how many packs you must buy to cover a year. A larger pack normally lowers the unit price, but if you cannot use the heads before the bristles age, the effective cost per month of use can be worse.
How often should heads be replaced?
The American Dental Association advises every three to four months, or sooner if the bristles are matted or frayed. Three to four calendar months is roughly 13 to 17 weeks, which is why the calculator takes weeks directly rather than assuming an exact conversion. Manufacturer instructions for your handle take precedence.
Can two people share one brush head?
No. This calculator assumes each person has their own head. Whether two people can share a powered handle is a separate question governed by the manufacturer instructions.
Is the annualised figure what I will spend?
Not necessarily. It is a rate, not a budget. Use the purchase budget line for what you actually pay in a year, and the annualised figure for comparing packs and brands.

Sources

  1. American Dental Association. Toothbrush care and replacement guidance — www.ada.org/resources/ada-library/oral-health-topics/toothbrushes
  2. NHS. How to keep your teeth clean — www.nhs.uk/live-well/healthy-body/how-to-keep-your-teeth-clean/
  3. Cochrane review. Powered versus manual toothbrushing (CD002281) — www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD002281.pub3/full

Brush heads with the listed compatibility and pack size

Head counts, handle models and prices stated on the listing rather than left to inference.

See the brush head range