Ownership Share Calculator: Work Out Each Co-owner’s Percentage
Enter what each person contributes and see the tenants-in-common split - to two decimal places, totalling exactly 100%.
To calculate each co-owner's share of a property, divide what that person contributed by the total contributed by everyone, then multiply by 100 - so $180,000 of a $300,000 deposit is a 60% share, normally recorded on the title as tenants in common.
Last updated July 2026
When two or more people buy a property together, the first number that has to be right is who owns what percentage. This calculator takes what each person is contributing and returns each owner’s share, reconciled so the percentages total exactly 100%.
Add a property value and it also shows what each share is worth in dollars today - the starting point for a buyout, a refinance, or simply checking the title matches the deal.
How this calculator works
- Enter each co-owner's name and what they are putting in - deposit, cash contribution, or the value of an existing share. Anything you all agree counts as a contribution can go in.
- Each person's percentage is their contribution divided by the total contributed. Because rounding to two decimals can leave the set at 99.99%, the residual is allocated by largest remainder so the shares always total exactly 100.00%.
- Add an optional property value to convert each percentage into a dollar figure. That is the number you would start from in a buyout negotiation.
A worked example
A parent puts in $180,000 and their daughter $120,000 towards a $300,000 deposit. The parent owns 60%, the daughter 40%, and that is what should be recorded on the title as tenants in common.
Three friends splitting evenly is where naive maths breaks: 33.33% three times is 99.99%. This calculator returns 33.34 / 33.33 / 33.33 so the shares are exactly 100% - the same rule Laddered applies to real properties.
Australia and the United States
The math is the same wherever you buy. For country-specific tax and legal detail - stamp duty and CGT in Australia, closing costs and capital gains in the US - read the guide for Australia or the United States.
Good to know
- Ownership is allocated in proportion to what each person contributes. You can agree a different split in a co-ownership agreement - contribution share is the common default, not a legal rule.
- This reflects the starting position. If contributions change over time, the shares may need to be revisited under the terms you agreed.
- Educational estimate - not legal, tax or financial advice.
Frequently asked questions
How do you calculate each owner’s share of a property?
Divide what that person contributed by the total everyone contributed, then multiply by 100. Someone putting in $180,000 of a $300,000 deposit owns 60%. Record the result on the title as tenants in common so the shares are legally documented.
What is a tenants in common percentage?
Tenants in common is the ownership structure that lets each co-owner hold a defined, unequal share - 60/40, 45/35/20, whatever matches the deal. Each owner can sell or leave their share independently, unlike joint tenancy where a deceased owner’s share passes automatically to the survivors.
Can co-owners have unequal shares?
Yes, as tenants in common. Unequal shares are the normal outcome whenever people contribute different amounts, and recording them on the title is what stops an uneven deal being treated as a 50/50 one later.
Should the mortgage repayments change our ownership percentages?
That is a decision to make up front. Some co-owners fix the shares at the deposit split; others let ongoing contributions move the percentages over time. Both work - what causes trouble is not deciding, then arguing about it years later.
Why do the percentages need to add up to exactly 100?
Because a title cannot record 99.99% of a property. Rounding three equal shares to two decimals leaves a stray hundredth, so this calculator allocates the residual to the largest remainder - giving a set that is both fair and registrable.