Computes X% of Y and what-percent-of-what (X is what % of Y) in two side-by-side panels with precise decimal arithmetic. Essential for everyday math — tips, discounts, tax rates, grade scores, and statistical comparisons where quick percentage answers are needed. Numbers never leave your device — every calculation runs locally in your browser.
Content reviewed October 2026 · About Toolzum
Compute your overall course percentage from comma-separated assignment grades and their matching weights — Exam Heavy presets included. Numbers never leave your device — every calculation runs locally in your browser.
Compute semester GPA from course grades and credit hours with credit-weighted math on the standard 4.0 scale — quick academic snapshot. See what straight B's earn — free, local, no signup.
Convert a single course percentage into its letter grade on the built-in plus/minus scale — see that an 85 earns a B instantly. Free, local, no signup.
Convert between time units including seconds, minutes, hours, days, weeks, months, and years with precise decimal results. Input never leaves your device — everything runs locally in your browser.
Computes GST-inclusive and GST-exclusive amounts for Indian tax slabs (5%, 12%, 18%, 28%) with net, GST value, and total shown.
Two modes: X% of Y (20% of ₹1,500 = ₹300) and what-percent-of-what (45 is 25% of 180). Covers tips, discounts, tax, and grade math.
A 20%-off price of ₹800 means original = 800 ÷ 0.80 = ₹1,000 — not 800 × 1.20 (₹960). Always divide by (1 − rate) to undo a percentage decrease.
10% off then 10% off again is 19% total, not 20%: ₹100 → ₹90 → ₹81. Each discount applies to the reduced base — chain them by hand by feeding each result back in as the next Y.
Full decimal precision (e.g., 33.333…% for 1/3), rounded for display only. Useful for tax and statistical comparisons where rounding early compounds errors.
No. All computation runs locally in your browser. Nothing is transmitted or stored.
Percentage Difference Calculator
Calculate the percentage difference between any two numbers. Useful for comparing data sets, prices, and measurements. Numbers never leave your device — every calculation runs locally in your browser.
Ratio Calculator
Simplify any two-number ratio to lowest terms via GCD — paint mixes, screen sizes, shares. Reduce 150:225 to 2:3 in one pass — free, runs locally.
Rounding Calculator
Round numbers using 5 modes: round half up, banker's rounding, floor, ceil, and truncate. Shows step-by-step explanation with the digit being rounded. Numbers never leave your device — every calculation runs locally in your browser.