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What Is a Prorate Calculator?
A prorate calculator figures out the exact amount you owe, or are owed, when a billing period is split partway through. Instead of paying a full month's rent when you moved in on the 18th, or a full year's subscription when you cancelled after nine months, proration gives you a charge that reflects only the days you actually used.
Proration shows up everywhere money changes hands on a schedule: residential rent, annual software licenses, employee salaries during a partial pay period, HOA fees, utilities, and insurance premiums. Any time a fixed recurring charge needs to be split across fewer days than the full cycle, proration is the right tool.
This calculator handles the most common scenarios, monthly rent, annual subscriptions, bi-weekly payroll, and custom billing cycles. Enter your numbers and it returns not just the prorated amount, but the daily rate, days charged, and how much you're saving compared to a full period.
If you want to double-check your landlord's math, verify an HR department's payroll calculation, or just understand what a service should charge you, this is where to start. Our team of financial researchers built it using the standard daily-rate method used by accountants and property managers across the U.S.
How to use this prorate calculator
The calculator takes less than a minute to use. Here's exactly what each step means and how to get an accurate result the first time.
How we calculate your prorated amount
The math behind proration is transparent and straightforward. Here's exactly how the numbers work.
Complete guide to proration
Prorated Rent: How It Works
Prorated rent is the most common use case for this calculator. When a tenant moves in partway through a month, they shouldn't pay for days before they had access to the property. The standard calculation divides the monthly rent by 30, regardless of the actual calendar month length, and multiplies by the number of days occupied.
Most landlords use this 30-day method. It means a tenant moving in on the 20th of any month pays for 11 days (20th through 30th). That's $660 on a $1,800/month apartment. If your landlord is using actual calendar days instead, the number shifts slightly, February gives tenants a better deal, July a slightly worse one.
Under the Uniform Residential Landlord and Tenant Act (URLTA), landlords in many states are required to prorate rent for partial months. Check your state's tenant rights laws if you're unsure whether your landlord is obligated to prorate. Landlords can also read our landlord proration guide for state-specific considerations and best practices.
Prorating Annual Subscriptions and Services
Software subscriptions, streaming services, and membership programs often charge annually upfront. When you cancel early or start mid-year, the question is what refund, if any, you're owed.
Most services use a 365-day year for annual proration. A $120/year subscription costs $0.329/day. Cancel after 200 days and you've used $65.75 worth of service; the remaining $54.25 is what a fair proration-based refund would look like. Whether you actually get that refund depends on the service's refund policy, but knowing the prorated value gives you a number to point to.
Salary Proration: Partial Pay Periods
HR departments prorate salaries when an employee starts or leaves mid-period, or when a pay period straddles a leave of absence. The standard method divides the period's full pay by the number of scheduled working days, then multiplies by the days actually worked.
For a monthly salary of $5,000 with 22 working days in the month, a new hire starting on day 5 who works 18 days would earn: ($5,000 ÷ 22) × 18 = $4,090.91. This calculator uses total calendar days, which is common for salaried roles, if your company uses working days, enter the appropriate numbers in the custom fields.
When Landlords Are Required to Prorate
Landlord obligations vary by state and sometimes by city. In states that have adopted the URLTA or similar tenant protection statutes, landlords must charge only for days the tenant actually occupied the unit. Some states leave it up to the lease terms. If your lease is silent on proration, the local default rules apply.
Resources like Nolo and the Consumer Financial Protection Bureau (CFPB) publish state-by-state guides to tenant rights. If you're in a dispute with your landlord over a prorated amount, knowing your state's rules is the first step.
Who should use this calculator?
Proration comes up for a wide range of people, not just tenants. Here's who gets the most out of this tool:
- Tenants moving in mid-month: verify the amount your landlord quotes you before handing over a check
- Tenants moving out early: calculate what you should owe for your last partial month and compare it to your landlord's invoice
- Landlords: generate a clear, defensible prorated figure to put in writing for new or departing tenants
- HR and payroll professionals: quickly check partial pay period amounts for new hires, departures, or unpaid leave
- Small business owners: prorate vendor invoices, SaaS subscriptions, or service contracts that started mid-billing-cycle
- Accountants and bookkeepers: verify client invoices or reconcile partial-period charges against contract terms
If you're handing over money, or expecting money back, for a partial billing period, this calculator gives you a number you can stand behind.
Proration guides & explainers
Need more detail on a specific proration scenario? Our guides cover the most common situations with real worked examples.
Start here if you're new to the concept.
RentStep-by-step with worked numbers.
RentWhat to expect when moving in mid-month.
RentWhich method your landlord uses and why it matters.
PayrollHR and payroll scenarios, explained.
TenantAnd how to avoid them, with dollar examples.
Frequently Asked Questions
Prorated rent is calculated by dividing the monthly rent by the number of days in the month, then multiplying by the number of days the tenant will occupy the unit. For example, if rent is $1,500/month for a 30-day month and the tenant moves in on the 15th, the prorated rent is ($1,500 ÷ 30) × 16 = $800. The move-in day itself is typically counted as an occupied day.
Both methods are legitimate. The 30-day (banker's month) method is simpler and used by many landlords and billing systems. The actual calendar day method (28-31 days) is more precise and may be specified in your lease or service agreement. Check your contract to see which method applies. If not specified, 30 days is the most common default.
Divide the full pay period salary by the total working days in that period, then multiply by the days actually worked. For salaried employees, use business days (typically 21-23 per month). For hourly or per-calendar-day calculations, use total calendar days. Many employers use the annual salary divided by 2,080 hours (52 weeks × 40 hours) for the most precise daily rate.
Typically yes, the move-in day counts as an occupied day. If you move in on March 15 in a 31-day month, you are charged for 17 days (March 15 through March 31). However, some lease agreements specify that the move-in day is not charged. Always check your specific lease terms for clarification on how move-in and move-out days are handled.
Divide the annual cost by 365 (or 366 for a leap year) to get the daily rate. Then multiply by the number of remaining days. For example, canceling a $120/year subscription with 200 days remaining: ($120 ÷ 365) × 200 = $65.75 refund or $54.25 prorated charge for the used portion.
In insurance, proration means adjusting a premium based on the actual coverage period. If you cancel a policy mid-term or make changes that affect your rate, the insurer calculates the prorated premium for the days covered. Some insurers use a "short rate" method that includes a penalty, while "pro rata" cancellation gives a true proportional refund.
If you use actual calendar days, yes, February proration will differ from March. A $1,500/month rent prorated for 10 days would be $535.71 in February (28 days) but $483.87 in March (31 days). Using the 30-day standard method avoids this variation, which is why many landlords prefer it for consistency.
For utilities, divide the total bill by the number of days in the billing cycle, then multiply by the days each party is responsible. If a roommate moves out mid-month on day 18 of a 30-day cycle with a $150 electric bill, their share is ($150 ÷ 30) × 18 = $90. The remaining tenant pays $60 for the final 12 days.
Most states do not have specific laws requiring prorated rent for partial months. However, it is standard practice in the rental industry and is typically addressed in the lease agreement. In some jurisdictions, tenants who give proper notice may be entitled to a prorated refund for unused days. California, for instance, requires landlords to refund prorated rent when a tenant provides adequate notice to vacate.
Proration divides a charge proportionally over time based on actual usage (like partial-month rent). Amortization spreads a debt or cost over a fixed schedule of payments with interest (like a mortgage). Proration is simpler, it is purely a time-based division. Amortization involves a payment schedule where each installment covers both principal and interest in changing proportions.
Prorate Calculator Team
Our editorial team includes financial researchers and property management professionals who verify every formula against AICPA standards, Nolo guidance, and the Uniform Residential Landlord and Tenant Act. We review and update all content quarterly.