Splitting party costs equally between families is only fair if both invite the same number of guests. This calculator splits the shared costs, such as the venue, equally, and the costs per guest, such as food and party bags, by how many guests each family invited. Friends of both children are split between the families.
How it works
- Enter the shared costs: things that cost the same however many guests come, like the venue, an entertainer or the cake.
- Enter the cost per guest: food, drinks and a party bag for each child.
- For each family, enter the guests only they invited. Enter friends of more than one family once, under “Guests invited together”.
- Each family pays its part of the shared costs, plus the cost of its own guests and its part of the guests invited together.
The formula
Family’s share = shared costs ÷ number of families + cost per guest × (own guests + guests invited together ÷ number of families).
If you choose to split the shared costs by guests instead, each family’s part of the shared costs follows its number of guests too. Every amount is rounded to the cent, so the shares add up to the exact total.
Worked example
Mia and Leo have a joint party. The venue and an entertainer cost 240.00 EUR. Food and a party bag cost 12.00 EUR per child. Mia’s family invited 14 children, Leo’s family invited 9, and 5 children are friends of both.
| Family | Guests | Shared costs | Guest costs | Total |
|---|---|---|---|---|
| Mia’s family | 14 + 2.5 | 120.00 EUR | 198.00 EUR | 318.00 EUR |
| Leo’s family | 9 + 2.5 | 120.00 EUR | 138.00 EUR | 258.00 EUR |
| Total | 28 | 240.00 EUR | 336.00 EUR | 576.00 EUR |
Split equally, each family would pay 288.00 EUR, so Leo’s family would pay 30.00 EUR towards guests that Mia’s family invited.
Common questions
Should the shared costs be split by guests too?
You can choose either in the calculator. Splitting the venue equally treats it as the cost of having a party at all; splitting it by guests treats it as part of what each guest costs. Agree on one before booking.
Can more than two families share a party?
Yes. Add as many families as you need. Guests invited together are split equally between all of them.
What about a child who is a friend of only some of the families?
The calculator splits guests invited together between every family. For a child shared by only two of three families, add the child to one of those families’ own guests, or settle that cost between the two separately.
What about extras one family wants?
Leave them out of the calculator, and let that family pay for them, for example a second cake or a gift for its own child.
Can I send the result to the other family?
Yes. Create a link to share and send it. The amounts travel inside the link; nothing is stored on this website.