OmniCalc Classic is a free online multi-calculator suite that runs entirely in your browser with no download required. It combines a basic calculator, a scientific calculator with trigonometry, logarithms, and bracket resolution, a step-by-step fraction solver, a percentage and growth calculator, and an accurate stopwatch with countdown timer in one tool. The suite supports multiple themes, keyboard shortcuts, tactile sound tones, full screen mode, and persistent calculation history, and it works on desktop and mobile browsers.
Use the mode tabs above to switch between the basic calculator, scientific calculator, fraction calculator with steps, percentage calculator, and online stopwatch and timer. Every calculator is free, works instantly in your browser, and supports keyboard input.