proratacalc Pro rata calculators that show their work.

FINANCIAL CALCULATOR

Pro Rata Calculator

This free pro rata calculator works out a proportional amount for any partial period — and shows the exact formula with your own numbers. Choose the day-count basis your employer, landlord, or contract actually uses, so your figure matches theirs.

Calculate a pro rata amount Sample values shown — edit any field to calculate instantly.

Pick Salary to scale an annual figure to your hours or days; pick Amount over a period for a one-off proportional split (rent, a fee, a refund).

Start from a common case:
$
Day-count basis and endpoint counting

Day-count basis

— why your number might differ

Counts the real number of days in both the period and the part you used. Leap years count Feb 29 automatically.

Count both the first and last day?
Pro rata amount
$840.00 That’s 70% of the full amount.
Per-day value: $40.00 · Days used: 21 of 30
Calculation method See the exact formula with your numbers
Day-count basis
Actual / actual
Endpoints
Inclusive
Counted days
21 of 30
  1. Days in the full period (Actual / actual): 30
  2. Days used (Actual / actual): 21
  3. Proportion used: 21 ÷ 30 = 0.70
  4. Pro rata amount: $1,200.00 × 0.70 = $840.00

Figures are illustrative. Change the day-count basis above to see how each convention moves the result.

Where it shows up

The same proportion, in a lot of places

Pro rata is one idea — a share of a full amount for the part of a period that applies — but it turns up under different names. The most common places people need it:

Insurance refund Cancel a policy early and the unused part of your premium comes back pro rata. See the insurance refund calculator — or, if an early-cancellation penalty applies, the short-rate cancellation calculator. To go further and estimate what actually reaches your account after fees and a minimum-earned clause, use the prorated calculator for insurance.
Prorated pay Start or leave a job mid-period and your salary is scaled to the days you actually worked. The prorated salary calculator matches payroll's working-day method.
Any partial amount A fee, a bonus, a shared cost — anything split by time or quantity. Use the calculator above with the day-count basis your contract, employer, or insurer uses.

▲ Why the day count changes the answer

The only thing that moves a pro rata figure is how you count the units. A year can be treated as a real 365 days, a fixed 360, or 366 across a leap year; a month can be calendar days or working days. If a figure you were given doesn't match, switch the day-count basis above and compare the steps — that is usually where the gap is.

How it's calculated

In proportion — nothing more

Pro rata simply means in proportion. Take the value of one unit (one day, one month, one share), then multiply by the number of units that apply to you:

pro rata amount = full amount × (units used ÷ total units)

The only thing that changes the answer is how you count the units — which is exactly what the day-count basis above lets you control.

Questions

Frequently asked

What does "pro rata" mean?
Pro rata means "in proportion". It splits a full amount across the part of a period that actually applies — a partial-month salary, the unused part of an insurance premium, a refund, or any figure tied to time or quantity. The calculator above works out that proportion and shows the formula on your own numbers.
How do I calculate a pro rata amount?
Take the value of one unit — one day, one month, one share — then multiply by the units that apply to you: full amount × (units used ÷ total units). Enter your figures above and the steps show the exact math on your own numbers.
What is a pro rata insurance refund?
When you cancel a policy early, the pro rata refund is your unused premium — the premium for the days left on the term, with no penalty. The dedicated insurance refund calculator works it out with the exact day count so you can check the figure your insurer gives you.
Pro rata or short-rate on a cancellation?
A pro rata refund returns your unused premium in full proportion — usually when the insurer cancels. A short-rate refund subtracts an early-cancellation penalty, so it comes out smaller — common when you cancel mid-term. Your policy says which one applies.
Should I use working days or calendar days?
There is no single correct basis — calendar days, working days, or a fixed 360 / 365 all give different figures. The calculator shows the day-count basis it used, so you can match the one your employer, insurer, or contract actually applied instead of guessing.
Pro rata vs prorated — are they the same thing?
"Prorated" is the common US spelling and "pro rata" the original Latin phrasing; both mean the same proportional calculation.
Why doesn't my figure match the one I was given?
Usually the day-count basis or a rounding rule differs — or, on an insurance cancellation, a short-rate penalty. Switch the basis above and compare the steps until it lines up with the figure you were given.
Is a pro rata salary before or after tax?
Before. Pro rata gives a proportion of the gross figure; tax and deductions come off afterwards, so your take-home is lower. For a mid-month paycheck, the prorated salary calculator matches payroll's method.

Also try

More single-purpose calculators

Insurance refund calculator →Short-rate cancellation calculator →Prorated salary calculator →Prorated bonus calculator →