Department № 08

Everyday.

Little tools that pull real weight.

12 tools in this department

Everyday calculators for small but common decisions: tip splitting, sleep-cycle timing, hours worked, time arithmetic, and other quick tools that don't belong to any single field. Keep them bookmarked for the moments when you need a fast, accurate answer without opening a spreadsheet or hunting through a search results page.

01
Discount Calculator
Sale price after a percentage or fixed discount.
02
GPA Calculator
Grade point average from letter grades and credit hours (US 4.0 scale).
03
Grade Calculator
What score do I need on the final to hit a target grade?
04
Hours Calculator
Compute worked hours between start and end times, minus a break — with decimal total.
05
Time Calculator
Add or subtract hours, minutes, and seconds — or find the difference between two times.
06
Sleep Cycle Calculator
Best bedtime or wake time based on 90-minute sleep cycles.
07
Password Strength
Estimate password entropy and time to crack under a plausible attack.
08
Random Number
Cryptographically-random integer in a range.
09
Dice Roller
Deterministic dice roller for any common die — reproducible, with totals and range.
10
Shoe Size Converter
Convert between US Men, US Women, EU, and UK shoe sizes using foot length.
11
Ring Size Calculator
Convert ring inner diameter or circumference to US, UK, and EU sizes.
12
Electricity Cost Calculator
Cost to run an appliance — kWh used plus monthly and yearly projections.

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