Rental Security Deposit Calculator

A rental security deposit is a sum of money paid by a tenant to a landlord before moving in. It serves as financial protection for the landlord against potential damages, unpaid rent, or lease violations. Understanding how much you will need to pay upfront is essential for budgeting your move.

Security deposit amounts are typically calculated as a multiple of the monthly rent. In many jurisdictions, landlords can charge between one and three months’ rent as a deposit, and a growing number of places cap it by law.

California changed in 2024 and a lot of guidance online is still wrong about it. Assembly Bill 12 took effect on 1 July 2024 and caps security deposits at one month’s rent, furnished or not. The old two-month and three-month limits are gone. A narrow exception lets a small landlord who owns no more than two residential properties totalling no more than four units charge up to two months, and that exception does not apply where the tenant is a service member.

Elsewhere: in the United Kingdom the Tenant Fees Act 2019 caps deposits at five weeks’ rent where the annual rent is under £50,000, and six weeks above it. Several US states have no cap at all.

The practical consequence is that if you are in California and a landlord asks for two months on a large portfolio, that is not a negotiation, it is unlawful.

This calculator estimates your security deposit based on your monthly rent and the deposit multiplier (how many months’ rent the deposit equals). It also calculates the total move-in cost, which typically includes the first month’s rent, the security deposit, and optionally the last month’s rent if required by the landlord.

The formula is simple: Security Deposit = Monthly Rent multiplied by Deposit Multiplier. Total move-in cost adds the first month’s rent and any additional required payments. Some landlords also charge non-refundable fees for pets, application processing, or key deposits, which you can include as an additional fee.

When budgeting for a new rental, always ask the landlord for a complete breakdown of all upfront costs. Keep records of the property condition at move-in (photos and written notes) to protect your deposit when you eventually move out. Most jurisdictions require landlords to return deposits within 14 to 60 days after the lease ends, minus any legitimate deductions for damage beyond normal wear and tear.