You can track storage unit rentals in a spreadsheet with one row per unit, one row per tenant and one row per payment, and it works for a small facility. Move to software when late fees, autopay, online rentals or lien dates start to slip, and move payments and reminders first because that is where money leaks.
The outline below is a free template you can build in Excel or Google Sheets in about an hour.
What you need to track
Every rental has five facts that must always be right:
- Which unit it is and its size.
- Who rents it and how to reach them.
- The rent and the due date.
- What has been paid and what is owed.
- What has happened if they are late.
If your system answers those five at any time, it works. If it cannot, it is time to change.
A free spreadsheet template (outline)
Use three tabs. Each one has a clear job.
Tab 1: Units
| Column | Example | Notes |
|---|---|---|
| Unit ID | B12 | Match the door |
| Size | 10x10 | |
| Square feet | 100 | Width x length |
| Type | Interior | Drive-up, climate, outdoor |
| Street rate | $110 | Today's price to a new tenant |
| Status | Rented | Rented, vacant, reserved, locked, hold |
Tab 2: Tenants and leases (your rent roll)
| Column | Example | Notes |
|---|---|---|
| Unit ID | B12 | Links to the Units tab |
| Tenant name | ||
| Phone | ||
| Mailing address | Needed for lien notices | |
| Alternate contact | ||
| Move-in date | 2026-03-18 | |
| Rent | $105 | In-place rate |
| Due day | 18 | Or "1st" if first-of-month billing |
| Paid through | 2026-11-17 | See paid-through date |
| Balance | $0 | Formula from Tab 3 |
| Autopay | Yes or No | |
| Notes | Calls, promises, issues |
This tab is your rent roll: every unit, tenant, rent and balance on one page.
Tab 3: Payments and charges
| Column | Example |
|---|---|
| Date | 2026-10-18 |
| Unit ID | B12 |
| Type | Rent, late fee, payment, refund |
| Amount | $105 |
| Method | Card, cash, check, bank |
| Note |
Balance for a unit = sum of charges minus sum of payments for that unit. In Google Sheets or Excel, use a SUMIF on the Unit ID. Keep every row; never overwrite a payment.
A worked example: finding past-due rent
Say you have 40 units rented at an average of $80, so billing is $3,200 a month. On the 20th, you filter the Tenants tab for balance above $0 and find 5 tenants owing $80 each and one owing $160.
- Past-due tenants: 6 of 40 = 15%.
- Past-due balance: 5 x $80 + $160 = $560.
- Share of billing: $560 / $3,200 = 17.5%.
If this takes five minutes, the sheet is working. If it takes an hour because the sheet is out of date, that is a sign.
Rules that keep a spreadsheet honest
- One person edits. Two editors cause conflicts.
- Update the same day. Enter a payment when it arrives.
- Never delete rows. Mark vacated tenants as "moved out" and move them to an archive tab.
- Back it up. Download a copy weekly to a different place.
- Lock formulas. Protect the balance column.
- Use a date format that does not change (YYYY-MM-DD).
- Write notes for every call or promise, with the date.
Where spreadsheets break
| Problem | What happens |
|---|---|
| Late fees | You forget or apply them unevenly |
| Autopay | Not possible; you chase every payment |
| Online rentals | None; tenants must call or visit |
| Reminders | Manual emails or texts |
| Lien dates | You track notice and sale dates by hand; a miss can ruin a sale |
| Gate codes | Changed by hand, if at all |
| Proration | Easy to get wrong. See anniversary vs first-of-month billing |
| Reports | Take time to build, easy to get wrong |
| Records | One lost file loses everything |
| Growth | Past a few dozen units, errors multiply |
This is a general picture, not a count. There is no fixed number of units where you must switch. The test is whether you are missing things.
The five signs it is time to switch
- You have missed a late fee or a lien date.
- Tenants ask to pay online and you say no.
- You are spending hours on reminders and reconciling.
- You have more than one site or more than one editor.
- You cannot answer "what is my occupancy and delinquency?" in ten minutes.
What to move to software first
You do not have to move everything at once. In order:
- Payments and autopay. The fastest gain: fewer late payers, fewer calls. See autopay and payments.
- Reminders and late fees. Automatic and consistent.
- Online rentals. Tenants rent at any hour. See online rentals.
- Lien tracking. Timelines by state. See self storage lien laws.
- Reports. Rent roll, occupancy, delinquency. See reports.
- Gate codes. Tied to accounts. See gate access.
Choosing software
Read how to choose self storage software for 25 questions to ask. For the category, see storage unit software. Compare the total monthly cost at your size on the pricing page and others.
Moving your spreadsheet in
Clean your data first.
- Make sure every unit has a unique ID.
- Fix duplicate or missing tenants.
- Check that every rent and balance is correct.
- Give each tenant a phone and email.
- Export each tab as a CSV file.
- Send it to the new vendor.
- Check the import. Totals must match your sheet.
Tenants who pay by cash or check have nothing to carry over. Tenants who want autopay add a payment method online. Read how to switch self storage software for the full plan. Keep the spreadsheet as a record.
Keep your records
Keep the sheet, bank statements and receipts. The IRS says you must keep records that support an item of income, deduction or credit on your return until the period of limitations for that return runs out, generally 3 years and longer in some situations. Lease and lien records may need longer for legal reasons; ask your attorney.
Mistakes
- Using one sheet for everything.
- Overwriting numbers instead of adding rows.
- Skipping the mailing address, then needing it for a lien notice.
- No backup.
- Waiting until a lien deadline is missed to switch.
Handy formulas for the sheet
Assuming your Tenants tab has rows 2 to 200 and columns as listed above:
| Goal | Formula idea |
|---|---|
| Rented units | Count of rows where Status is Rented |
| Physical occupancy | Rented units divided by total units |
| Monthly billing | Sum of the Rent column for rented units |
| Past-due tenants | Count of rows where Balance is above 0 |
| Past-due balance | Sum of Balance where Balance is above 0 |
| Balance for one unit | Sum of Amount in Payments where Unit ID matches |
The exact function names differ between Excel and Google Sheets, but each of these is a count or a sum with a condition.
What software adds that a sheet cannot
A sheet records what happened. Software also does things: it charges the card, sends the reminder, posts the late fee, turns off the code and tracks the lien dates. Ask yourself which of those you do by hand now, and how many hours a month they take. If the answer is more than a few hours, price the software against your time. The pricing page lists Stitch plans, and storage unit software covers the category.