UD5 Toolkit
Shoelace Length Calculator – Online Eyelet Pairs & Pattern
Enter number of eyelet pairs and lacing style to find the correct shoelace length in inches/cm. Never buy too short.
Advanced Online Scientific Calculator - History & Memory
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Simple Haversine Distance Calculator – Online City‑to‑City
Enter two city names or coordinates and get the straight‑line distance in miles/km. Local calculation.
Fishing Sinker Weight vs. Depth Calculator – Online Drift Speed
Estimate the sinker weight needed to hold bottom in current based on line diameter, depth, and current speed.
Jigsaw Puzzle Size Calculator – Online Table Size for Pieces
Enter piece count and piece size to estimate finished dimensions. Check if it fits your table.
Toilet Paper Stock Calculator – Online How Long Will It Last?
Enter rolls remaining and household size to estimate weeks of supply. A humorous yet practical aid.
Popcorn Yield Calculator – Online Kernels to Popped Volume
Enter amount of kernels and see estimated popped volume. Plan movie night snacks perfectly.
Speaker Placement Calculator - Online Home Theater Stereo Angle
Calculate ideal stereo speaker placement (toe-in, distance from wall) for best soundstage. Visual diagram. For audiophiles. Local tool.
TV Viewing Distance Calculator - Online Size vs Resolution Guide
Find the optimal TV size for your room or the best viewing distance based on screen size and resolution (1080p, 4K, 8K). Simple THX/SMPTE reference.
Blood Alcohol Content Estimator - Online BAC Calculator
Estimate BAC based on gender, weight, drinks consumed, and time. Uses Widmark formula. Educational tool, never encourage drunk driving. Local only.
Simple Interest Calculator - Online Principal Rate Time Tool
Compute simple interest and final amount given principal, annual rate, and duration. Also reverse-calculates rate or time. Local only.
Week Number & Start/End Dates - Online ISO 8601
Enter any date and get its ISO week number, plus the start and end dates of that week. Quick reference.
Relative Luminance Calculator - Online WCAG Metrics
Enter a hex color and get its relative luminance per WCAG definition. Understand why this matters for contrast.
Workday Calculator with Holidays - Online Add Business Days
Add N business days to a date, skipping weekends and optionally entering custom holidays. Regional presets.
Date Duration Calculator - Online Calendar & Workdays
Calculate the exact number of days, weeks, months, and workdays between two dates. Visual calendar highlights. Perfect for projects.
Bubble Tea Recipe Calculator - Online DIY Boba Proportions
Choose your cup size and sweetness level, and get exact proportions for tea, milk, syrup, and tapioca pearls. Perfect homemade boba every time.
Battery Series/Parallel Calculator - Online Voltage & Capacity
Combine multiple identical batteries in series and parallel and see the resulting voltage and total capacity. Electronics helper.
Subscription Rename & Cost Calculator - Online Saver
Track your subscriptions, calculate monthly and yearly totals, and find savings by pausing unused services. Local data.
Sample Size Calculator - Online Survey & A/B Test Tool
Determine the minimum sample size needed for a survey or A/B test with a given confidence level and margin of error.
Bayes' Theorem Calculator - Online Probability Update Tool
Easily compute posterior probabilities given prior, likelihood, and marginal likelihood. Visual diagram. All local.
Megapixel Calculator - Online Print Size & Resolution
Find out how large you can print based on image resolution in pixels. Understand DPI and megapixels.
F‑Stop Calculator - Online Aperture & Depth of Field Reference
Learn about f‑stops and their effect on light and depth. Calculate equivalent exposure adjustments. Educational.
CAGR Calculator - Online Compound Annual Growth Rate
Find the CAGR of an investment given start and end values over a time period. Instant growth rate.
Waist‑to‑Hip Ratio Calculator - Online Body Shape Health Indicator
Measure your waist‑to‑hip ratio and learn about associated health risks. WHR interpretation. Educational only.
Day of the Week Calculator - Online Find Weekday from Date
Find what day of the week any past or future date falls on. Uses Zeller’s congruence. Fun historical reference tool.
Polygon Centroid Calculator - Online Center of Mass
Find the centroid (center of mass) of any convex polygon by entering vertex coordinates. Useful for physics and design.
Timeline Creator - Online Generate Visual History Chart
Build a vertical timeline by entering events with dates and descriptions. Export as image or HTML. Perfect for project milestones.
Tip Pool Calculator - Online Fair Share Splitter for Staff
Fairly distribute pooled tips among staff based on hours worked or points. Customizable percentages. All calculations local and private.
Sales Tax Calculator - Online U.S. State Tax Estimator
Estimate the total price after adding US state sales tax. Select state, enter amount, and see breakdown. Simple and quick, perfect for shoppers.
Compound Interest Calculator - Online Investment Growth Tool
Project how your savings and investments grow over time with compound interest. Interactive chart and detailed table. Free and anonymous.
Mortgage Calculator - Online Home Loan & Amortization Tool
Estimate monthly mortgage payments with amortization schedule. Input loan amount, interest rate, and term. All calculations performed securely on your device.