Teething Timeline Calculator

Work out teething timeline instantly with clear inputs, formula shown and shareable results.

About Teething Timeline Calculator

The common paediatric rule of thumb is teeth equals age in months minus six, capped at the full set of twenty primary teeth by around thirty months. Eruption timing varies widely, so the rule is a guide for reassurance rather than a schedule, and the count of teeth still to come is the more useful planning figure.

Formulas

Expected teeth

expected teeth = age in months - 6, floored at 0 and capped at 20

Remaining

remaining = 20 - teeth already through

Worked example

With the default values below, Teething Timeline Calculator returns Teeth expected by this age of 2. Change any input above and every figure here is recalculated in your browser.

Inputs used

Baby's ageminimum 1 months: 8 months
Teeth already throughaccepts 0–20: 2

Results

Teeth expected by this age: 2
Teeth ahead of or behind the guide: 0
Baby teeth still to come: 18
Months until a full set is usual: 22.0

Step by step

1Values used
2Expected teeth
3Remaining
4Teeth expected by this age= 2
5Teeth ahead of or behind the guide= 0
6Baby teeth still to come= 18
7Months until a full set is usual= 22.0

Assumptions and limits

The result is derived only from the 2 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 1 decimal place, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

How is the Teething Timeline figure worked out?

expected teeth = age in months - 6, floored at 0 and capped at 20. The common paediatric rule of thumb is teeth equals age in months minus six, capped at the full set of twenty primary teeth by around thirty months.

Why does this matter?

Eruption timing varies widely, so the rule is a guide for reassurance rather than a schedule, and the count of teeth still to come is the more useful planning figure.

What do I need to enter?

Enter baby's age, teeth already through. The defaults shown are a realistic worked example — swap in your own figures to get a result you can use.