Reverse and original-price tools
Work backward from a percentage or a sale price without losing the base.
Explore reverse percentages →Free, transparent calculators
Calculate it. Understand it. Move on.
CleanPercent 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—
Expanded tool library
More everyday questions, one clear method at a time
Explore additional percentage tools, planning calculators, user-assumption salary math, compound-return illustrations, and transparent trade arithmetic. Each tool stays in your browser and states what it cannot know.
Score and progress tools
Calculate weighted results, percentage points, and task progress clearly.
Explore score tools →Salary and returns math
Use your own assumptions for take-home pay and compound-return illustrations.
Explore money tools →Trade arithmetic, not signals
Calculate hypothetical long or short outcomes and stop-distance unit math.
Explore trade math →Three-city planning
Compare three clocks before trying to find a fair meeting time.
Open three-city planner →Future meeting checker
Choose a date first, then compare the local time in two places.
Check a future date →More than an answer
Every calculation explains its method
A calculator should not hide the most important assumptions. CleanPercent shows the formula, explains what the result means, and flags cases where a simple percentage can mislead.
Formula shown
Every result includes the arithmetic used so you can check it, learn it, or paste it into notes.
Browse the formula library →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 →