Sinking Fund Capex Reserve Calculator

Reserve for future capex. This calculator sizes deposit.

Capex cost

Years until needed

Reserve earning rate %

Existing reserve balance

Monthly deposit required

$1,294

Future shortfall gap

$246,494

Existing grown by event date

$203,506

How the math works

Existing grown = current × (1+rate)^years. Shortfall = cost − grown. Monthly = FV annuity reverse.

$450k capex in 12 years, $120k existing at 4.5%: existing grows to $203k, shortfall $247k. Monthly deposit: $1,290 to fill gap. Reserve discipline prevents operational crisis when event hits.

How to Use

Enter capex cost.
Enter years until needed.
Enter reserve earning rate %.
Enter existing reserve balance.
Read monthly deposit required.

Frequently Asked Questions

Why sinking fund?

Known capex (roof at year 20, HVAC at year 15, elevator at year 25). Spread cost as monthly reserve. Avoids cash shock when event occurs. Reserves earn modest interest. Also required by many lenders for deferred maintenance risk.

Reserve amount?

Match to actual lifecycle: roof $18-30/SF every 20-25 years. HVAC $8-15/unit per month. Elevator $150-300/unit per month when building has. Parking $2-5/SF every 15-20 years. Site-specific — engineer reports useful lives.

Where hold?

Money market (safe, low yield ~4-5%). CDs (ladder by maturity). T-bills (safe, tax-advantaged for some). Lender-required escrow (often below-market interest). Prefer operator-controlled if lender allows — better yields, flexibility.