Online Tools / General Tools

General Tools

Everyday calculators and practical utility tools for percentages, discounts, dates, time, education, construction, networking and common tasks.

Percentage Calculator

Calculate percentages, percentage increases, decreases and what percentage one number is of another.

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Discount Calculator

Calculate discount amounts, savings and final prices quickly.

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Age Calculator

Calculate exact age between two dates in years, months and days and show total days.

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Business Days Calculator

Calculate business days between two dates with configurable weekends and optional custom holidays.

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Time Calculator

Add or subtract days, hours, minutes and seconds and calculate a resulting duration.

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Date Calculator

Find date differences or add and subtract days, weeks and months from a starting date.

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Hours Calculator

Calculate elapsed hours and minutes between two clock times, including overnight shifts.

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Grade Calculator

Calculate weighted course grades and estimate the score required on remaining work to reach a target.

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GPA Calculator

Calculate a credit-weighted GPA on common numeric scales and optionally include prior cumulative credits.

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Conversion Calculator

Convert common length, mass, temperature, area, volume, speed, time, energy and data units.

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Concrete Calculator

Estimate concrete volume for rectangular and circular forms and convert the result to common volume units.

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Subnet Calculator

Calculate IPv4 subnet boundaries and basic IPv6 prefix information from an IP address and CIDR prefix.

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Password Generator

Generate random passwords locally with controls for length, character sets and repeated characters.

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General Tools

Everyday calculators and practical utility tools

Use Tervilo General Tools for quick calculations and practical everyday tasks involving percentages, discounts, dates, time, education, construction, networking and other common problems. The tools are designed to give you a useful result quickly while keeping the inputs and units clear.

When a calculation needs more explanation, the related Calculator Guides show the formula, explain the inputs and provide worked examples. This combination lets you solve a task first and then understand how the result was obtained.

Calculator Guides

Learn the formulas and methods behind common everyday calculations with clear examples and practical explanations.

How to Calculate Business Days Between Two Dates Learn how to calculate business days between two dates, including weekends, custom holidays, inclusive and exclusive date counting, and common mistakes. Password Generator Guide: Length, Entropy and Safer Passwords Generate random passwords locally with controls for length, character sets and repeated characters. Subnet Calculator Guide: CIDR, Network and Host Addresses Calculate IPv4 subnet boundaries and basic IPv6 prefix information from an IP address and CIDR prefix. Concrete Calculator Guide: How It Works, How to Use It and Important Limitations Estimate concrete volume for rectangular and circular forms and convert the result to common volume units. Hours Calculator Guide: How It Works, How to Use It and Important Limitations Calculate elapsed hours and minutes between two clock times, including overnight shifts. Date Calculator Guide: How It Works, How to Use It and Important Limitations Find date differences or add and subtract days, weeks and months from a starting date. Age Calculator Guide: How It Works, How to Use It and Important Limitations Calculate exact age between two dates in years, months and days and show total days. Conversion Calculator Guide: How It Works, How to Use It and Important Limitations Convert common length, mass, temperature, area, volume, speed, time, energy and data units. GPA Calculator Guide: Credits, Grade Points and Cumulative GPA Calculate a credit-weighted GPA on common numeric scales and optionally include prior cumulative credits. Grade Calculator Guide: Weighted Grades and Final Grade Planning Calculate weighted course grades and estimate the score required on remaining work to reach a target. Time Calculator Guide: How It Works, How to Use It and Important Limitations Add or subtract days, hours, minutes and seconds and calculate a resulting duration. How to Calculate Age from Date of Birth: Formula and Examples Learn how exact calendar age is calculated from a date of birth, including years, months and days, with examples.

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