Guide
How Tip & Loan Calculator works
A closer, formula-level look at exactly what happens when you click Calculate.
"How much should I tip" and "what will my monthly payment be" sound like two unrelated questions, but both reduce to a short formula that is surprisingly easy to fumble by hand, particularly once a bill needs splitting unevenly or two loan offers need comparing.
The tip side of the tool takes the bill, applies a tip percentage, totals it, and divides evenly among the group. The loan side runs the same amortization math banks use internally, converting a principal, an annual interest rate, and a term in months into a single fixed monthly figure.
Step by step
1. Pick a mode
Switch between “Tip & split” for a restaurant bill and “Loan payment” for financing math.
2. Enter your figures
For a tip: the bill, tip percentage, and number of people. For a loan: the amount, annual rate, and term in months.
3. Read three results at once
Each mode shows a small set of related numbers together, so you see the whole picture rather than one isolated figure.
4. Adjust and compare
Change the tip percentage or loan term and watch every number update immediately, which makes comparing options fast.
Checked examples
Both formulas below are the exact ones used by the calculator above, worked through with a fresh set of numbers.
| Calculation | Formula | Result |
|---|---|---|
| $108 bill, 22% tip, split 6 ways | tip = 108 × 22/100; total ÷ 6 | $21.96/person |
| $20991 loan at 5.9% for 60 months | M = P·r(1+r)^n ÷ ((1+r)^n−1) | $404.84/mo |
Good situations to use this in
- Deciding how much to tip when the group disagrees on the right percentage.
- Working out how much interest a loan will cost in total over its lifetime.
- Checking that a tip suggested by a payment terminal actually matches the percentage shown.
- Planning ahead for how a longer loan term trades off against a higher total interest cost.
- Splitting a restaurant or bar tab fairly among a group, including the tip.
Try it yourself
Head back to the tip & loan calculator to run your own numbers, or try the simple interest calculator for a related calculation.