Calculators — 28 Free Online Tools
All calculators run 100% in your browser — free, private, no sign-up.
Quick answers for everyday maths. This collection includes a percentage calculator, age calculator, date difference and working days calculators, time and hours calculators, GPA / CGPA / marks percentage tools for students, an attendance calculator, fraction and average calculators, a full scientific calculator, plus unit converters for area, volume, speed, data storage, currency, time zones and number systems.
Every calculator shows its working instantly as you type, runs entirely in your browser, and is free with no sign-up. Students, teachers, and professionals use these daily — choose yours below.
Age Calculator
Find exact age in years, months & days.
Percentage Calculator
All common percentage calculations.
Discount Calculator
Final price after discount & savings.
Date Difference
Days, months & years between dates.
Tip Calculator
Split the bill and calculate tips.
Area Converter
Convert between sq m, sq ft, acres, etc.
Volume Converter
Convert ml, l, gallons, cups, fl oz.
Speed Converter
Convert km/h, mph, m/s, knots.
Data Storage Converter
Convert bits, bytes, KB, MB, GB, TB with base toggle.
Number System Converter
Live conversion between binary, octal, decimal, hex.
Roman Numeral Converter
Convert numbers 1–3999 to Roman numerals and back.
GPA Calculator
Add courses and calculate your GPA.
Sales Tax Calculator
Add tax or reverse-calculate price before tax.
Scientific Calculator
Advanced calculator with trig, log, memory.
CGPA to Percentage Converter
Convert CGPA to percentage or vice versa with CBSE 9.5 multiplier and custom factors.
Attendance Calculator
Check current attendance percent and know exactly how many classes you can skip or must attend.
Working Days Calculator
Count working days between dates, excluding weekends and custom holidays. Ideal for leave planning.
Currency Converter
Live exchange rates for 150+ currencies with offline caching.
Time Zone Converter
Convert date & time between any two time zones, handles DST automatically.
Grade Calculator
What score do you need on your final exam? Instant calculation with target table.
Fraction Calculator
Add, subtract, multiply, divide fractions. Mixed numbers, simplified output, and steps.
Average Calculator
Mean, median, mode, range, min, max, count, sum — paste numbers, get stats live.
Standard Deviation Calculator
Population or sample standard deviation with variance and step‑by‑step working.
Work Hours Calculator
Calculate daily/weekly work hours, breaks, and total pay. Handles overnight shifts.
Time Calculator
Add or subtract time durations and find the difference between two dates/times.
Electricity Bill Calculator
Estimate electricity bill from units. Editable slab rates, fixed charges & duty. Works for all state boards.
Fuel Cost Calculator
Calculate trip fuel cost and monthly commute. Round trip, person split, cost per km and litres needed.
Marks Percentage Calculator
Single or multi‑subject marks percentage. Also shows approximate CGPA (÷9.5).
Frequently Asked Questions
How accurate are these calculators?
Each calculator uses standard, well-documented formulas and is tested against reference values. Where conventions differ (like CGPA scales), the assumptions are stated on the tool page.
Can students use these for exams preparation?
Yes. The GPA, CGPA to Percentage, Marks Percentage, Attendance and Grade calculators are built specifically for students in India and abroad.
Do these calculators work offline?
Once a page has loaded, the calculation itself runs in your browser without needing the internet.