Money Tools

Security Deposit Interest Calculator

Estimate simple interest earned on a security deposit over time.

Updated April 18, 2026
Free online tool
Planning and research use

Why this page exists

Some renters want to estimate whether a security deposit may have earned interest during the lease, especially in places where tenant-deposit interest rules exist. This calculator helps visitors estimate simple interest earned on a security deposit from the deposit amount, annual interest rate, and time period entered.

Interactive tool

Run the estimate

Enter your numbers and read the result first, then use the sections below to understand what affects the outcome.

Calculator

Security deposit interest calculator

Estimate simple interest earned on a security deposit over a chosen number of years.

Result

$54

Estimated simple interest earned on the security deposit from deposit amount multiplied by the annual interest rate and time period entered.

Estimated interest earned$54

Total value with interest$1,854

Deposit amount used$1,800

Rate and time used1.50% for 2.00 years

$1,800 at 1.50% for 2.00 years produces about $54 of simple interest in this estimate.
This helps with move-out planning when the real question is how much interest may have accumulated on top of the original deposit amount.
Treat the result as a planning figure only, because some locations require specific rates or handling rules and others do not require tenant deposit interest at all.

This is a simple-interest estimate only. Tenant-deposit interest rules vary by state, city, lease type, and how the deposit is actually held.

Planning note

Last updated April 18, 2026. Use this tool to compare scenarios and plan ahead, then confirm important details with the lender, employer, insurer, contractor, or other qualified provider involved in the final decision.

How it works

What the calculator is doing

Enter the original security deposit, annual interest rate, and time period in years.

The calculator applies simple-interest math to estimate interest earned over the time entered.

It shows both the estimated interest and the total deposit value with interest added.

Understanding your result

This is a simple estimate meant for planning and comparison. It can help frame whether deposit interest might be meaningful, but actual legal requirements and payout rules vary by location and lease details.

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Examples

Ways people use this tool

Example scenarios help turn a quick estimate into a more useful comparison or planning step.

Estimate possible deposit interest before move-out

A renter can use the result to understand whether deposit interest may be material enough to review in the final accounting.

Compare short and long lease terms

Running two time periods shows how a one-year stay and a multi-year stay can change the potential interest amount.

When to use it

Good times to run this calculator

Use this when you want a quick estimate of how much simple interest a security deposit may have earned over the lease period.

It is especially useful when you are reviewing move-out expectations and want a rough number before checking the local rules or final landlord statement.

Assumptions and limitations

The estimate assumes simple interest rather than compounding interest and assumes the same annual rate over the full period entered.

It does not determine whether deposit interest is legally required, what rate must be used, or how the landlord must account for it.

Common mistakes

Avoid the usual input mistakes

Using a guessed rate that does not match the rule or account treatment in the relevant location can make the estimate feel more precise than it really is.

Treating the result like a legal entitlement without checking local tenant rules can lead to the wrong expectation.

Practical tips

Use the estimate as a starting point, then compare it with the final deposit accounting and the actual tenant rules that apply where the rental is located.

If the lease lasted across multiple years with different rates, run separate scenarios to see how sensitive the estimate is.

Worked example

Walk through a realistic scenario

A worked example shows how the estimate behaves when the inputs resemble a real planning decision.

Estimate simple interest on a held deposit

A renter wants to translate a held deposit into a rough interest estimate before checking the final move-out paperwork.

1. Enter the deposit amount, annual interest rate, and time period in years.

2. Estimate the interest earned with simple-interest math.

3. Add the interest to the original deposit to see the total value in the planning estimate.

Takeaway: The result helps frame the conversation, but the real answer still depends on the lease terms and the local deposit-interest rules.

FAQ

Common questions

How is deposit interest estimated here?

The calculator uses simple-interest math: deposit amount multiplied by annual interest rate multiplied by the time period in years.

Does every rental deposit earn interest?

No. Deposit-interest requirements vary by state, city, lease type, and how the deposit is held, so some rentals may not owe interest at all.

Why is this different from a legal deposit statement?

Because the calculator does not try to model local statutes, required rates, bank-account rules, or notice requirements. It only provides a simple planning estimate.

Related tools

Keep comparing

Security-deposit, return, rent-proration, and budget tools help connect the interest estimate to the broader move-in and move-out cash picture.

Simple-interest and rent-to-income tools add nearby context when the deposit question is part of a wider rent and cash-planning decision.

Money ToolsUpdated April 17, 2026