Free Online Calculator Tools 20 tools
This collection covers the everyday calculations people actually search for: percentages, discounts, sales tax, tips, and bill splitting for money math; BMI, calories, and age for health and personal use; compound interest, margins, and mortgage payments for financial planning. Developers and network admins get a subnet mask calculator, pixel density (PPI) tool, CPM and bandwidth calculators, plus practical date and time difference calculators that count days, months, or hours between two points. Running pace, GPA, and aspect ratio are covered too. Every calculator updates the result live as you type and states its formula clearly, so you can trust and verify the number. All computation happens locally in your browser — no data leaves your device, no account is required, and the answer is there in milliseconds.
Percentage Calculator
Find what percent one number is of another, plus percentage increase and decrease.
Percentage Change Calculator
Calculate the percent increase or decrease between two values instantly.
Aspect Ratio Calculator
Calculate missing width or height to keep any aspect ratio, with common presets.
Discount Calculator
Work out the sale price and amount saved from any discount percentage.
Sales Tax Calculator
Add or remove sales tax from a price and see the tax amount clearly.
Compound Interest Calculator
Project compound interest growth with monthly contributions and compounding periods.
BMI Calculator
Calculate Body Mass Index from height and weight with category guidance.
Age Calculator
Calculate exact age in years, months, and days from any birthdate.
Date Difference Calculator
Count the exact number of days, weeks, months, and years between two dates.
Time Difference Calculator
Calculate the duration between two times or dates in hours and minutes.
CPM Calculator
Calculate cost per mille for ad campaigns from spend and impressions.
Margin / Markup Calculator
Convert between profit margin and markup from cost and selling price.
GPA Calculator
Calculate GPA from course credits and letter grades, 4.0 scale.
Calorie Calculator
Estimate daily calorie needs using BMR formulas and activity level.
Pace Calculator
Calculate running pace, speed, and estimated finish times from distance and time.
Mortgage Calculator
Estimate monthly mortgage payments from loan amount, rate, and term.
Tip Calculator
Split a bill and tip among friends with per-person totals in seconds.
Subnet Mask Calculator
Compute subnet masks, network and broadcast addresses, and usable hosts.
Pixel Density (PPI) Calculator
Calculate pixels per inch from screen resolution and diagonal size.
Bandwidth Calculator
Estimate transfer time for files over any connection speed.