Date & Time
Calculate dates, times, spans, and working days.
Free Online Calculator Tools
Precision tools for dates, math, units, and daily planning. Built for speed and accuracy.
Math
Solve percentages, formulas, and geometry checks.
Everyday
Useful calculators for daily life and work.
Popular Converters
View all 12 toolsLengthTranslate units while keeping the original value visible.AreaTranslate units while keeping the original value visible.WeightTranslate units while keeping the original value visible.VolumeTranslate units while keeping the original value visible.SpeedTranslate units while keeping the original value visible.Data SizeTranslate units while keeping the original value visible.
Tools Classification
Pick a calculator category by purpose and open the directory that fits your task.
Why use it
Fast checks without losing context.
QK Calculator keeps the input, category, and result close together, so quick answers stay readable when you return to a task later.
- Static pages load quickly on desktop and mobile.
- Calculator pages link to related tools and guides.
- No account is needed for everyday calculations.
Result30 daysMay 19 to June 18
Related6 toolsDate, time, math, units
Guides30 postsSmall practical examples
Tools Guides
Three starter guides connect everyday questions to calculator pages.
Date planning
How to Plan a Project Date Without Rebuilding Your Schedule
Plan project finish dates from a fixed start and known durations—without rebuilding the...Read guide Related: Date Difference CalculatorConversion
Centimeters to Inches: A Practical Workflow for Mixed Specs
Convert cm to inches in a repeatable workflow when product specs, drawings, and store...Read guide Related: LengthMath
Percent of a Number Examples for Discounts, Grades, and Budgets
Work percent-of-a-number problems for discounts, grades, and budget slices—with examples...Read guide Related: Percentage CalculatorFrequently Asked Questions
Short answers for visitors who want to choose a calculator quickly.
Are these tools free?
Yes. The calculator pages are available without sign-up and run as lightweight static pages.
Do calculator inputs leave my browser?
The current calculator interactions run in the browser, so quick values can be checked without an account workflow.
Can I open tools on mobile?
Yes. The home modules, category pages, calculator forms, and blog cards use responsive layouts.
Where should I start?
Use Quick Access for the full directories, or start from a category card when you already know the type of tool.
Quick Access
Jump straight to the main directories.