Accurate, instant calculators for everyday math, finance, and date operations. All free, no sign-up, works on any device.
Calculate exact age in years, months, days, hours, and seconds. Includes zodiac sign, Chinese zodiac, planet ages, and next birthday countdown.
8 calculation modes: basic percentage, increase/decrease, discount, profit margin, GST, and markup. Instant results with copy button.
Calculate monthly EMI, total interest payable, and full amortization schedule for home, car, or personal loans.
Find the exact difference between two dates in years, months, days, weeks, and working days.
Convert between 100+ units across length, weight, temperature, area, volume, speed, and more.
Calculate shipping costs, volumetric weight, and dimensions for packages and parcels.
Online calculators go beyond simple arithmetic. They handle complex, multi-step calculations that would be tedious or error-prone by hand — such as EMI amortization schedules, GST-inclusive pricing, percentage changes across multiple values, or precise date difference calculations that account for leap years and calendar irregularities.
Unlike spreadsheets, online calculators are purpose-built with the right formula, the right input validation, and clear output — reducing the chance of mistakes. They also provide contextual information: our Age Calculator, for example, doesn't just show your age in years — it shows your age in heartbeats, hours of sleep, and your position on multiple cultural calendars.
All DocsConverter calculators run entirely in your browser. There's no data sent to any server, no account needed, and no waiting for a response from an API. Just instant, accurate results.
How does the Age Calculator handle leap years?
Our Age Calculator uses JavaScript's Date object which correctly handles all calendar rules including leap years. It calculates your precise age by comparing your birth date to the current moment, accounting for every calendar irregularity.
What is EMI and how is it calculated?
EMI (Equated Monthly Instalment) is a fixed payment made by a borrower to a lender at a specified date each calendar month. EMI = [P × R × (1+R)^N] / [(1+R)^N - 1], where P is the principal loan amount, R is the monthly interest rate, and N is the number of monthly instalments.
How do I calculate a percentage increase?
Percentage increase = ((New Value - Original Value) / Original Value) × 100. Our Percentage Calculator handles this and 7 other calculation modes automatically — just select the mode and enter your values.
What is GST and how does the GST calculator work?
GST (Goods and Services Tax) is an indirect tax used in India. Our calculator supports both adding GST to a base price and removing GST from a GST-inclusive price. Select the GST rate (5%, 12%, 18%, or 28%) and your direction (add or remove).
How accurate are these calculators?
All calculations use IEEE 754 double-precision floating-point arithmetic (JavaScript's native number type). For most practical calculations, this provides accuracy to 15+ significant digits. For critical financial decisions, always verify with a qualified professional.