Monthly-only path
Headline × months, with escalation applied at each annual anniversary, plus admin fee, plus insurance for the full stay.
Calculator
What will storage actually cost you?
Self-storage listings show a one-month headline. Real stays average 20 months, facilities raise rates ~10%/yr on existing customers, and most quotes don't include insurance and admin fees. Plug in your numbers and see all three paths side by side.
Results
Headline × months $2,136
What renters mentally budget — ignores fees and hikes.
Month-to-month (real)
$2,556
Annual escalation + admin + insurance.
Annual prepay (year 1)
$2,449
Year 1 prepaid at discount, then monthly with hikes.
Rate-locked
$2,449
Headline held for the lock period, escalation after.
The honest gap
The renter expected the headline × months figure. Real month-to-month is $420 higher — that's fees plus rate hikes. A real rate-lock facility saves you $107 vs. the month-to-month path over your stay.
How the math works
Four pure functions, every default sourced.
Annual prepay path
Year 1 paid up front at the discount; remaining months at the escalated rate. If your stay is ≤ 12 months, the whole stay is prepaid.
Rate-locked path
Headline held for the lock duration; escalation starts at the first month after the lock expires.
Climate premium
When climate control is on and the facility doesn't expose a separate climate-controlled rate, we apply a composite +35% to the headline rent — sourced from public REIT disclosures.
All four functions live in shared/calculator-math.ts as pure (no I/O,
no DOM) TypeScript. The same module pre-computes the "12-month cost" column on
every facility page.