You need to make a surprising number of hires to attain net increases in ops capacity

In an org with a moderate growth rate, an operations team will often need to hire for half of its staffing every year. Consider a 10-person operations team inside a 40-person organisation which is moderately growing — say 20% per year — and which wants its ops capacity to stay in equilibrium with organisational demands, rather than improve or worsen its net service delivery. The sliders below show what they should expect.

Annual growth of the rest of the organisation; ops headcount keeps up, holding the ops share of staff steady (unless you set catch-up growth below).
Total staff today, including the ops team.
Of whom this many are operations staff.
Annual expected turnover.
Annual rate of ops staff who leave to go to other teams — a loss to the ops team, often a win for the org.
This increases the operations team by x% relative to the org compared to today — e.g. +10% takes a team that's 25% of staff to 27.5% by year end. (The maths accounts for the new ops staff themselves adding to org size, which is why catching up takes more hires than you'd naively think.) Consider whether you want to keep operations capacity, relative to the organisational demands placed upon it, increasing, decreasing, or staying the same. If you're currently under capacity, you'll want to hire enough to catch up with the organisation (and you might need to stay there for a while in order to work through systems debt). If, given trade-offs, you're okay where you are, hold this steady. If you're currently over capacity, you should reduce growth and let org demands catch up (perhaps significantly, if you don't have operational systems debt).
hires this year

Replacing staff who leave the org Replacing moves to other teams Keeping up with org growth

On the default numbers: my gut thinks this is awfully high — but I think it's what I should take as my prior. Wild…

Run it forward five years

Headcount compounds with growth; the hiring load compounds with it. Fractional hires are shown as-is — in practice they arrive lumpy.

YearOps team at startOrg sizeOps share of orgHires neededAs % of teamCumulative hires

Caveats: this treats the rates as independent and stable, assumes service delivery just holds its progress (there's no crazy AI shit going on, etc.), and the equilibrium framing means hiring isn't an occasional interruption to running an ops team — it's a permanent workstream.