How proportional splitting works
Each person pays a percentage of tax, tip, and fees based on their share of the pre-tax subtotal. If your items make up 30% of the food-and-drink subtotal, you pay 30% of the tax and 30% of the tip.
This is almost always fairer than splitting tax and tip evenly, because a bigger order naturally generates more tax and more server work. Someone who spent $60 on their meal should not pay the same $6 of tip as someone who spent $18.
Worked example
Three people at dinner. Tax: $12. Tip: $30. Total extras: $42.
- Alex ordered $60 (50% of the $120 subtotal)
- Jordan ordered $36 (30%)
- Priya ordered $24 (20%)
Everyone's total:
- Alex: $60 + 50% of $42 = $60 + $21 = $81
- Jordan: $36 + 30% of $42 = $36 + $12.60 = $48.60
- Priya: $24 + 20% of $42 = $24 + $8.40 = $32.40
Compare that with an even split of $42: everyone would pay $14 in extras regardless of what they ordered. Alex would save $7, Jordan would break about even, and Priya would overpay by $5.60.
When to use this instead of the full app
The proportional split calculator is great when everyone already knows their own subtotal (for example, when the receipt is already itemized in front of you).
If you'd rather each person pick their own items from a shared digital receipt and get their number automatically, use BillSplitterApp — it does the item-claiming and the proportional math without anyone having to sum their own subtotal.