Tip Calculator

WHAT IT DOES

Tip Calculator takes the guesswork out of dining out, group bills, and service gratuities. Enter your bill amount and instantly see the tip amount, total bill, tip per person, and total per person. Choose from preset tip percentages (10%, 15%, 18%, 20%, 25%) or enter a custom percentage for precise control. Specify how many people are splitting the bill, and the panel divides everything equally — no more mental math or awkward group calculations. All results update in real-time as you type.

WHERE IT RUNS

This script runs on every website you visit. Whether you are planning a dinner out, calculating delivery tips, splitting a group order, or working with expense reports, the panel is always available. It works alongside whatever you are doing — restaurant websites, delivery apps, group planning sites, or online calculators — staying accessible without interrupting your workflow.

HOW TO USE

Enter the bill total in the first field. Click a preset percentage button or type a custom percentage in the custom field. Enter the number of people splitting the bill. The results update automatically: tip amount, total bill with tip, tip per person, and total per person. Save custom percentages as presets by clicking "Set Custom" after typing your preferred rate — the panel remembers your custom presets across sessions. Click any history entry to reload previous calculations. Use the "Copy Total" button to copy the per-person total to your clipboard.

THE RECURRING CALCULATION MECHANISM

Tip Calculator uses a precise financial rounding model that matches how real point-of-sale systems handle currency. Each intermediate value — tip amount, total bill, per-person amounts — is rounded to two decimal places using standard rounding rules. This avoids the common problem of accumulating rounding errors from floating-point arithmetic, which can cause final totals to be off by a few cents when split among multiple people. The calculation sequence applies tips to the original bill first, then splits the total, ensuring that the per-person tip plus per-person bill always equals the total divided by the number of people.

THE PANEL

The panel is fully draggable and remembers its position per site. It minimizes to a compact floating bubble when collapsed. All settings — custom tip presets, default tip percentage, default number of people, and calculation history — persist across browser sessions using GM_setValue storage. Press the Escape key to close the panel. The panel automatically focuses the bill input field for quick keyboard entry.

PLEASE NOTE

This script requires the free BotGentz extension to run. Websites change their structure and behavior over time; if any functionality stops working, the script may need an update. No user data is sent anywhere — all calculation history, presets, and settings are stored locally in your browser. The script never reads or modifies password, hidden, or file input fields.