What is the pro rata share?
Type a full amount, your part and the whole it is for, such as a $60,000 salary for 24 of 40 hours. The pro rata calculator gives your proportional share, the percent and the amount per unit. Or split an amount among several parties in proportion to their shares, days or hours.
- Pro rata amount
- $36,000.00
The pro rata amount is $36,000.00 of $60,000.00.
- Share of the whole
- 60%
- Rest of the amount
- $24,000.00
- Amount per unit
- $1,500.0000
- Answer
- The pro rata amount is $36,000.00 of $60,000.00
Pro rata amount: $36,000.00. The pro rata amount is $36,000.00 of $60,000.00.
The results are estimates for information only. They are not financial, tax, or legal advice. Check the numbers with your lender or a qualified professional before you decide. Terms of use
How to calculate
Works out a pro rata share: an amount × part ÷ whole, such as a part-time salary or a bill for days used, or an amount split among several people in proportion to their shares.
Example with the default inputs (Work out One share, Full amount $60,000.00, Your part 24, The whole 40): The pro rata amount is $36,000.00 of $60,000.00.
Method: Pro rata amount = full amount × part ÷ whole. In a split, each party gets full amount × its units ÷ all units.
- The part and the whole are in the same units (hours, days, shares, square feet).
- A part larger than the whole gives more than the full amount, as with overtime.
- Amounts in the split list are rounded to the cent one by one, so they can differ from the full amount by a few cents in total.
Worked examples
Each example is checked against the calculator on every build.
- Work out One share, Full amount $60,000.00, Your part 24, The whole 40 gives Pro rata amount $36,000.00, Share of the whole 60%, Rest of the amount $24,000.00, Amount per unit $1,500.00.Source: IRS, Instructions for Form 1120-S, Shareholder’s Pro Rata Share Items, General Rule (each shareholder’s pro rata share is determined by the number of shares of stock owned each day and the total shares outstanding each day), https://www.irs.gov/instructions/i1120s (retrieved 2026-10-02)
- Work out One share, Full amount $1,200.00, Your part 73, The whole 365 gives Pro rata amount $240.00, Share of the whole 20%, Answer The pro rata amount is $240.00 of $1,200.00.Source: IRS, Instructions for Form 1120-S, Shareholder’s Pro Rata Share Items, General Rule (each shareholder’s pro rata share is determined by the number of shares of stock owned each day and the total shares outstanding each day), https://www.irs.gov/instructions/i1120s (retrieved 2026-10-02)
- Work out Split among parties, Full amount $10,000.00, Parties 50; 30; 20 gives Pro rata amount $5,000.00, Each party Party 1: $5,000.00 (50%); Party 2: $3,000.00 (30%); Party 3: $2,000.00 (20%).Source: IRS, Instructions for Form 1120-S, Shareholder’s Pro Rata Share Items, General Rule (each shareholder’s pro rata share is determined by the number of shares of stock owned each day and the total shares outstanding each day), https://www.irs.gov/instructions/i1120s (retrieved 2026-10-02)
- Work out Split among parties, Full amount $100.00, Parties 1; 1; 1 gives Pro rata amount $33.33, Each party Party 1: $33.33 (33.33%); Party 2: $33.33 (33.33%); Party 3: $33.33 (33.33%).Source: IRS, Instructions for Form 1120-S, Shareholder’s Pro Rata Share Items, General Rule (each shareholder’s pro rata share is determined by the number of shares of stock owned each day and the total shares outstanding each day), https://www.irs.gov/instructions/i1120s (retrieved 2026-10-02)
How it works
One share. For a full amount A, your part p and the whole w (in the same units):
- pro rata amount = A × p ÷ w
- share of the whole = p ÷ w × 100%
- rest of the amount = A − pro rata amount
- amount per unit = A ÷ w
Split among parties. For parties with units u₁, u₂, … and U = u₁ + u₂ + …:
- party k gets A × uₖ ÷ U, which is uₖ ÷ U × 100% of the amount
- amount per unit = A ÷ U
- the headline and the share of the whole are party 1's
This is the IRS's pro rata rule for S corporation items when the shares held do not change during the year; when they change, each day's shares are used, which is the same as using share-days as the units.
The maths runs in double precision.
Rules
- The full amount is $0 to $1 trillion. Parts and units are 0 to 10¹²; the whole is 10⁻⁹ to 10¹². The sum of the units must be more than 0.
- A part larger than the whole is allowed and gives more than the full amount.
- 2 to 20 parties.
Output format. Money in dollars and cents; the amount per unit to 4 decimals; the share to 4 decimals. "Each party" reads "Party 1: $5,000.00 (50%)", joined with "; ": each amount is rounded to the cent (halves up, from the value written to 15 significant digits), and each percent is Math.round(percent × 100) ÷ 100 with trailing zeros dropped. The answer sentence uses the same cent rounding.
Worked examples by hand
A $60,000 salary for 24 of 40 hours. 60,000 × 24 ÷ 40 = $36,000, 60% of full time; the rest is $24,000; $1,500 per weekly hour.
A $1,200 yearly bill for 73 days. 1,200 × 73 ÷ 365 = $240, 20%.
$10,000 split by 50, 30 and 20 shares. U = 100: $5,000 (50%), $3,000 (30%), $2,000 (20%).
$100 split three equal ways. 100 ÷ 3 = 33.333…: $33.33 each (33.33%).
Other questions people ask
What does pro rata mean?
"In proportion." A pro rata share is the part of an amount that matches your part of the whole: if you own 30 of 100 shares, you get 30% of a payout; if you use a service for 73 of 365 days, you pay 20% of the yearly fee.
How do I calculate a pro rata amount?
Multiply the full amount by your part and divide by the whole: pro rata amount = amount × part ÷ whole. A $1,200 yearly bill for 73 days is 1,200 × 73 ÷ 365 = $240.
How do I work out a pro rata salary?
Use hours (or days) as the part and the whole. A $60,000 full-time salary for 24 hours of a 40-hour week is 60,000 × 24 ÷ 40 = $36,000 a year, 60% of full time.
How is income shared pro rata among S corporation shareholders?
The IRS instructions for Form 1120-S say each shareholder's pro rata share is based on the shares owned each day and the total shares outstanding each day. If the shares do not change during the year, that is simply each holder's shares ÷ all shares. With 50, 30 and 20 of 100 shares, $10,000 splits into $5,000, $3,000 and $2,000.
Why do my split amounts not add up to the total?
Each amount is rounded to the cent on its own. $100 split three ways is $33.33 each, which adds to $99.99. Decide who gets the extra cent; the unrounded shares add up exactly.
Is prorated rent the same thing?
It is one case of it: rent × days lived there ÷ days in the month. The prorated rent calculator handles the month lengths and move-in dates for you.