Know the storage deal before you make the offer.
Free underwriting calculators for self-storage buyers: rent roll, NOI, lease-up, debt and returns. They run the same engine as the Storage Underwriter iPhone app.
- 8 calculators
- No sign-up
- 100% in your browser
Quick deal check
Sheet C-00Stabilized and valued at a 6.5% cap, it could be worth $1.54M more than the asking price, before lease-up time, closing costs and financing.
Underwrite it fully →Four questions decide what a facility is worth.
What does it earn today?
Unit mix, occupancy by size and loss to lease, from the rent roll.
What does it keep?
Ancillary income, collection loss and a real P&L with your management fee and taxes.
What can it become, and how fast?
Occupancy and rent to stabilization, month by month.
What does it return on your equity?
Debt, exit and IRR, with a sensitivity grid for when you're wrong.
Every number in a storage underwrite, one tool each.
- Deal AnalyzerFull acquisition underwriting: unit mix, lease-up, NOI bridge, debt, IRR and a sensitivity grid.
- Cap Rate & ValuationValue from NOI and cap rate, or the cap rate implied by an asking price, before and after tax reassessment.
- NOI & Expense RatioBuild NOI from rents, ancillary income and a quick expense ratio or a line-item P&L.
- DSCR & Loan SizingPayments, DSCR and debt yield, the maximum loan each lender test allows, and a seller second.
- Lease-Up & StabilizationMonth-by-month occupancy, rent and NOI from today to a stabilized facility.
- Break-Even OccupancyThe occupancy that covers operating expenses, and the occupancy that also covers debt service.
- Unit Mix & Rent RollGross potential rent, loss to lease, rent per square foot and occupancy by unit size.
- Expansion Yield on CostWhether adding rentable square feet to a facility you're buying creates value.
Where stabilized NOI comes from, line by line.
This is the NOI bridge for the app's built-in sample deal, a 410-unit facility bought at 80% occupancy with rents below market and a 9,000 SF expansion. Every figure is produced by the underwriting engine these calculators share.
Sample deal · NOI bridge
Illustrative- Stabilized value
- $7.59Mat 6.75% cap
- Value creation
- +$2.10M
- Levered IRR
- 25.1%5-year hold
- Equity multiple
- 2.84x
- Stabilized DSCR
- 1.51x
- Rent upside
- 20%weighted, to market
Illustrative assumptions only. Your results depend entirely on your inputs.
The reasoning behind the numbers.
- How to Underwrite a Self-Storage DealOne facility, start to finish: rent roll, T12, stabilization, debt, exit and returns.
- Self-Storage Cap RatesWhat published surveys report for cap rates, and how to pick going-in and exit caps.
- Value-Add Self StorageWhere the NOI growth in an under-managed facility comes from, line by line.
- Physical vs. Economic OccupancyUnit, square-foot and economic occupancy, and why the gap between them matters.
- Property Tax ReassessmentWhy the seller's tax bill is not your tax bill, and how to underwrite the difference.
- Ancillary IncomeTenant protection, fees, retail and truck rental: how to underwrite each line.
- Due Diligence ChecklistWhat to request and verify, mapped to the underwriting input each item confirms.
- Reading a T12 and Rent RollHow to reconcile seller financials, the rent roll and bank deposits.
- Self-Storage ReturnsCash-on-cash, IRR, equity multiple and yield on cost: formulas and what drives them.
- Self-Storage LoansBank, SBA, CMBS and seller financing compared, and how lenders size a loan.
- SBA Loans for Self StorageSBA 7(a) and 504 terms from sba.gov and how each fits a storage acquisition.
- Seller FinancingStructuring a seller second behind a bank loan, and what it does to DSCR and returns.
Common questions
Are these self-storage calculators free?
Yes. Every calculator on this site is free, needs no account and runs entirely in your browser. Nothing you type is sent to a server.
Where do the calculations come from?
They are a TypeScript port of the calculation engine inside the Storage Underwriter iPhone app, tested against outputs produced by the app's Swift engine so that the website and the app give the same answers.
Who is this site for?
People evaluating or buying existing self-storage facilities: first-time buyers of a small facility, experienced investors screening deals, and partners checking a sponsor's numbers.
What does the iPhone app add?
Saved deals, a line-item P&L that reconciles to your expense ratio, expansion modeling, a verdict against your own targets, and an 8-page PDF investment memorandum, all stored only on your phone.