UD5 Toolkit
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.
Tag: Calculator - Basic & Scientific
99+ toolsWeek 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.
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.
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.
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.
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.
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.
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.
Popcorn Yield Calculator – Online Kernels to Popped Volume
Enter amount of kernels and see estimated popped volume. Plan movie night snacks perfectly.
Megapixel Calculator - Online Print Size & Resolution
Find out how large you can print based on image resolution in pixels. Understand DPI and megapixels.
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.
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.
Workday Calculator with Holidays - Online Add Business Days
Add N business days to a date, skipping weekends and optionally entering custom holidays. Regional presets.
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.
Bayes' Theorem Calculator - Online Probability Update Tool
Easily compute posterior probabilities given prior, likelihood, and marginal likelihood. Visual diagram. All local.
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.
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.
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.
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.
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.
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.
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.
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.
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.
Subscription Rename & Cost Calculator - Online Saver
Track your subscriptions, calculate monthly and yearly totals, and find savings by pausing unused services. Local data.
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.
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.
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.
Moon Age Calculator - Online Days Since New Moon
Calculate the age of the moon in days since the last new moon. See illumination percentage. Simple algorithm.
Water Leak Cost Calculator – Online Drip to Gallon Waste
Select drip speed or running toilet and see gallons wasted per day and annual cost. Fix leaks!
Road Trip ETA Calculator - Online Arrival Time with Stops
Estimate arrival time with driving duration, breaks, and time zone changes. Plan your road trip precisely.
Body Fat Percentage Calculator - Online US Navy & BMI Method
Estimate body fat percentage using the US Navy circumference method or BMI-based formula. Private and instant, all data stays on your device.
Free Fall Calculator – Online Time, Speed, Distance
Enter height and get fall time and impact speed. Simple physics demo. Good for students.
Antenna Length Calculator - Online 1/4 Wave & Dipole Tool
Calculate antenna element lengths for a given frequency (or vice versa). Supports 1/4 wave, 1/2 wave, dipole. Useful for ham radio. Local only.
SVG Path Length Calculator - Online Measure Path
Paste an SVG path and calculate its total length. Useful for stroke‑dasharray animations and drawing effects.
Solar Noon Calculator - Online When Is Sun Highest
Enter a location and date to find the exact time of solar noon, sunrise, and sunset. Astronomy tool.
Elapsed Time Calculator - Online Duration Between Dates/Times
Enter two date‑time values and get the exact years, months, days, hours, minutes difference. Word output also.
Golden Ratio Calculator - Online Find Balanced Proportions
Enter a number to find its golden ratio long and short segments. Use for pleasing design layouts. Instant.
Macronutrient Calculator - Online Protein Carb Fat Split
Determine your ideal daily macronutrient intake based on TDEE, goal, and diet preference. Free nutrition planning tool with local computation.
Hourly Pay Calculator - Online Wage & Overtime Estimator
Calculate your weekly, monthly, or annual pay based on hourly wage and hours. Include overtime rates. Accurate and private.
Break‑Even Point Calculator - Online Units & Sales
Calculate the break‑even point in units and dollars. Input fixed costs, variable cost per unit, and price.
Sleep Debt Tracker - Online Cumulative Sleep Loss Calculator
Log daily sleep to see cumulative sleep debt or surplus over weeks. Visualizes chronic sleep loss trends. Stores data locally in your browser only.
Bike Gear Inch & Ratio Calculator - Online Cycling Tool
Calculate gear inches, meters of development, and speed ratio for any chainring/cog combination. For cyclists.
BMI Calculator - Online Body Mass Index Tool
Check your Body Mass Index using standard or metric units. Get a health category analysis instantly. Educational purpose only; data stays private.
Binary Calculator - Online Add Subtract Multiply Binary Numbers
Calculate with binary numbers: addition, subtraction, multiplication, and division. Also bitwise AND, OR, XOR. Programmer's tool, fully client-side.
Fraction Calculator - Online Add Subtract Multiply Divide
Perform arithmetic on fractions and get simplified results. Handles mixed numbers and improper fractions. Step-by-step display. Educational and precise.
Coaxial Cable Attenuation Calculator – dB Loss per 100 ft
Select a common coaxial cable type and frequency to see the signal loss in dB per 100 feet or meters. Plan your feedline with confidence.
Canning Altitude Adjuster - Online Boiling Water Processing Time
Enter your altitude to adjust canning processing times or pressure. Prevent botulism. Based on USDA guidelines. Essential for home canners.
Day of Year Calculator - Online Ordinal Date
Find out what day number of the year any date is (1‑366). Also shows days remaining. Simple reference.
Markup Percentage Calculator - Online Price & Margin
Compute the selling price from cost and desired markup percentage, or find the markup from cost and price.
Bandwidth & Download Time Calculator - Online
Estimate how long it takes to download/upload a file given bandwidth speed. Also convert between bits and bytes.
Discount Calculator - Online Sale Price & Savings Tool
Quickly find the final price after a percentage discount. Also works in reverse to find the original price. Handy for budget shoppers.
Crochet Hat Sizing Guide – Online Measure & Increase
Enter head circumference to get crown diameter and length. Perfect fit top‑down hats.
Liquid Fertilizer Dilution Calculator – Online Mix Ratio
Calculate how much liquid fertilizer concentrate to add per gallon of water based on desired N concentration.
Percent Error & Relative Error Calculator - Online Lab Report Tool
Calculate absolute error, relative error, and percent error between experimental and theoretical values. For science students. Instant local math.
Tree Carbon Sequestration Calculator - Online Environmental Tool
Estimate how much CO2 a tree captures over its lifetime based on species, age, and climate. Learn about your green impact. Educational local tool.
Aquarium Water Change Calculator - Online Safe Volume Replacement
Calculate how much water to change weekly to keep nitrates under control. Based on current nitrate level, desired level, and tank volume.
Color Distance ΔE Calculator - Online Perceptual Difference
Enter two hex colors and compute the CIE76, CIE94, and CIEDE2000 color difference. Understand how humans perceive color similarity.
DIY Electrolyte Powder Calculator – Online Sodium Potassium Glucose Ratio
Create your own oral rehydration solution by mixing salt, potassium, and sugar to WHO formula. Convert to teaspoon amounts.