The formula
total = Σ monthly spend × 12 × (1 + inflation)^year
Where it comes from
There is no table of spending by country here, and that is deliberate: the ones official bodies publish change every year, depend on household income and do not transfer from one country to another. The monthly figure comes from whoever knows theirs. What the calculation adds is the part nobody does in their head, which is compounding eighteen years of inflation onto a recurring amount.
How to work it out by hand
- Estimate your real monthly spend: food, clothes, childcare or school, activities and their share of housing
- Multiply by twelve for the year
- Apply inflation year by year, not once at the end
- Add up the years and add the one-off starting cost
What is worth knowing
The spending is not spread evenly across the years. The early ones are heavy because of childcare, which in many places costs more than a mortgage; then they drop once school starts, and rise again in the teens with food, clothes and activities. A flat monthly average is a convenient simplification, which is why it is worth looking at the final year too — the figure closest to what you will pay when the child is older. And it leaves out what is not paid in money: the hours of care, which in any serious study are the largest item of all.