UD5 Toolkit
Tiny House Cost Estimator – Online DIY Build Budget Tool
Breakdown of expected costs (materials, appliances, etc.) for a tiny house. Adjust percentages or enter custom. Local calculation.
Online Calculators - Math & More
99+ toolsD&D Magic Item Price Calculator – Online by Rarity & Edition
Select item rarity and consumable state to get a price range based on Dungeon Master's Guide tables. Quick reference.
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.
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.
Roof Snow Load Estimator – Online Ground Snow & Pitch Factor
Enter ground snow load and roof pitch to estimate the effective snow load on a sloped roof. Quick structural check for snowy regions.
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.
Print Readability Calculator – Online Minimum Font for Distance
Enter viewing distance to get the minimum readable print font size. Design posters and signs.
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.
Bayes' Theorem Calculator - Online Probability Update Tool
Easily compute posterior probabilities given prior, likelihood, and marginal likelihood. Visual diagram. All local.
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.
Online Scientific Calculator - Free Advanced Math Tool
Full-featured scientific calculator with trigonometric, logarithmic, and exponential functions. Clean interface and keyboard support. No installation required.
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.
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.
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.
Koi Pond Stocking Calculator – Online Gallons per Fish
Enter pond dimensions and filtration type to estimate safe number of adult koi. Prevent overcrowding.
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.
Elephant Toothpaste Demo Calculator - Online Reaction Ratios
Find safe mixing ratios for the classic elephant toothpaste demonstration. Volume adjustments for different container sizes.
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.
Daylight Length Calculator - Online Sunrise Sunset Duration
For any latitude and date, calculate the exact daylight hours. See golden hour. Useful for gardening and travel.
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.
Quarter of Year Finder - Online Q1 Q2 Q3 Q4 Tool
Enter any date and instantly know which quarter it belongs to. Also shows fiscal quarter if start month set.
Minutes to Decimal Hours - Online Time Conversion Tool
Convert minutes to decimal hours and vice versa. Essential for billing and payroll. Instant conversion with a handy chart.
Soda Ash Soak Calculator – Online Tie‑Dye Prep Ratio
Calculate water and soda ash needed to pre‑soak fabric for tie‑dye. Achieve vibrant, long‑lasting colors.
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.
Polygon Area Calculator - Online Irregular Shape Tool
Calculate the area of an irregular polygon by entering its vertex coordinates. Uses the shoelace formula. Pure math.
Credit Card Payoff Calculator - Online Debt Repayment Plan
Calculate how long it will take to pay off credit card debt with fixed monthly payments or a payoff goal. Understand interest costs fully.
Camp Stove Fuel Calculator – Online Days Left per Canister
Enter isobutane canister weight, meal count, and burn time per meal to estimate how many days your fuel will last. Plan your resupply.
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.
Epoxy Flooring Calculator – Online Sq Ft & Kit Quantity
Enter area to calculate how many epoxy floor kits you need. Consider priming coat.
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!
Web Image Size Calculator - Online KB & Dimensions Tool
Predict the file size of an image based on pixel dimensions and format (JPEG, PNG, WebP). Rough estimate. Local.
Chemical Equation Balancer - Online Stoichiometry Solver
Enter an unbalanced chemical equation and get the balanced coefficients instantly. Supports parentheses and ions. All local JavaScript algebra.
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.
Next Prime Number Finder - Online Integer Sequence
Enter any integer and quickly find the next prime number after it. Perfect for hashing and puzzles.
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.
Sleeping Pad R‑Value Calculator – Online Temperature Matching
Enter expected low temperature and get minimum recommended pad R‑value. Visual conductivity guide for winter camping.
Tire Size Visualizer - Online Compare & Dimensions
Enter two tire sizes and see a side‑by‑side comparison of diameter, width, and speedometer error. Local math.
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.
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.
Concrete Mix Calculator - Online Cement Sand Gravel Ratio Tool
Calculate required bags of cement, sand, and gravel for a given concrete volume using standard mix ratios (1:2:4, etc.). Supports metric and imperial.
Body Fat Percentage Estimator - Online US Navy & Covert Bailey Method
Estimate body fat percentage using neck, waist, hip (if female) measurements. Supports US Navy, Covert Bailey, and 3-site skinfold methods. No data sent to server.
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.
Timecard Calculator - Online Work Hours & Timesheet
Calculate total work hours and pay from time-in/out entries. Supports overtime and breaks. Generate a printable timesheet. All local.
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.