Formula shown
Every result includes the arithmetic used so you can check it, learn it, or paste it into notes.
Browse the formula library →Free, transparent calculators
Calculate it. Understand it. Move on.
Apex Percent gives you a result, shows the method, and explains the important limitations—without requiring an account or sending your numbers anywhere.
What is a percentage of a number?
Find a part when you know the total and the percentage.
Answer—
One number is what percentage of another?
Express a part of a non-zero total as a percentage.
Answer—
How much did a value change?
Calculate the relative change from a positive, non-zero starting value. For a zero or negative start, read the limitation below the answer.
Answer—
For rates such as 2% changing to 3%, distinguish percentage points (1 point) from percentage change (50%). Read the full explanation.
Discount, extra discount, and tax
See the effect of sequential discounts. The optional tax is calculated after discounts; actual retail and tax rules vary by location and seller.
Final amount—
More than an answer
Every calculation explains its method
A calculator should not hide the most important assumptions. Apex Percent shows the formula, explains what the result means, and flags cases where a simple percentage can mislead.
Limits made clear
Zero bases, negative values, sequential discounts, rounding, and time-zone daylight changes are explained, not hidden.
Read the methodology →Time-zone planning
Search more than 400 cities, compare the live local time, and see a simple working-hours overlap.
Open the time planner →Practical guides
Use numbers with better context
Discounts: why 20% + 10% is not 30%
A step-by-step guide to sequential discounts, final prices, and the question to ask before comparing offers.
Read the discount guide →Percentage points vs percentage change
Learn why a one-point movement can be a very large relative change, and when each measure fits.
Read the change guide →Percentages for school and projects
Understand scores, weighted components, progress tracking, and how to show your workings clearly.
Read the learning guide →Meeting times across borders
A practical planning routine that accounts for daylight saving time and people’s working hours.
Read the time-zone guide →