Which subtotal to use
This calculator expects the pre-tax subtotal from the receipt — the line labeled "subtotal" that appears before tax and tip. It applies tax and tip to that number.
If your receipt only shows the post-tax total, you can either enter that in the tip calculator (which does not add tax) or back out the pre-tax number by dividing by (1 + tax rate).
Worked example
Pre-tax subtotal: $92. Sales tax: 8.5%. Tip: 20%. Splitting evenly across 4 people.
- Tax: $92 × 0.085 = $7.82
- Tip on the pre-tax amount: $92 × 0.20 = $18.40
- Total: $92 + $7.82 + $18.40 = $118.22
- Per person: $118.22 ÷ 4 = $29.56
Tip on pre-tax or post-tax?
By default this calculator tips on the pre-tax subtotal, which is the technically correct method. If you'd rather tip on the post-tax total, use the "tip on post-tax total" toggle — the difference is usually a dollar or two on typical restaurant bills.
When even split isn't fair
If people ordered very different amounts, splitting the final total evenly overcharges the person who ordered the least. For those cases, use the proportional split calculator or the full BillSplitterApp itemized flow.