About this tool

Basic Calculator

A premium glassmorphic calculator. Supports basic arithmetic operators (+, -, *, /), signs, and calculation history.

This Basic Calculator lets you type a whole expression across the display — for example 12 + 7 * 3 — and evaluates it with standard operator precedence, so multiplication and division resolve before addition and subtraction rather than left to right the way a cheap pocket calculator does. Results are rounded to 8 decimal places to suppress binary floating-point noise, and the last 20 calculations stay in a log you can click to reload. It is for anyone doing quick arithmetic in a browser tab who wants to see the full expression, correct it, and check what they entered.

How to use Basic Calculator

1. 1

   Open Basic Calculator on AltFTool — it loads instantly in your browser.

2. 2

   Press the number keys (0-9) and the . key to build a value. AC resets the display to 0, the back-arrow key rubs out the last character, and +/- flips the sign.

3. 3

   Pick an operator from the tinted column — the keys are ÷, ×, - and + — or type +, -, * or / on your keyboard, which is also wired to the digits, Enter, Backspace and Escape.

4. 4

   Press = (or Enter) to evaluate. The answer replaces the display, the expression moves to the small line above it, and the run is added to the Calculation Log, which keeps the last 20 entries; anything the calculator cannot evaluate shows Error.

Why use Basic Calculator

• Precedence is respected

  2 + 3 * 4 returns 14, not 20, because the whole expression is evaluated at once instead of each operator being applied as you press it.

• Floating-point noise is trimmed

  Results are rounded to 8 decimal places and trailing zeros dropped, so 0.1 + 0.2 comes back as 0.3 rather than 0.30000000000000004.

• Full keyboard control

  Digits and the decimal point, + - * /, Enter or = to evaluate, Backspace to delete, and Escape or C to clear all work without touching the mouse.

Common use cases

• You are checking an invoice line and want to enter 4 * 250 + 18 as one expression instead of running three separate steps.
• You mistyped a digit halfway through a long sum and need backspace on the expression rather than starting over with AC.
• You worked out a figure two calculations ago and want to click it in the log to bring it back into the display.

Frequently asked questions