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+ toolsSimple Haversine Distance Calculator – Online City‑to‑City
Enter two city names or coordinates and get the straight‑line distance in miles/km. Local calculation.
Megapixel Calculator - Online Print Size & Resolution
Find out how large you can print based on image resolution in pixels. Understand DPI and megapixels.
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.
Elephant Toothpaste Demo Calculator - Online Reaction Ratios
Find safe mixing ratios for the classic elephant toothpaste demonstration. Volume adjustments for different container sizes.
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.
Loan Calculator - Online EMI & Amortization Schedule Generator
Calculate monthly EMIs for any loan type and see the detailed amortization schedule. Compare different interest rates and tenures with instant results.
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.
Age Calculator - Online Real-Time Age by Date of Birth
Find your exact age in years, months, and days. Calculate the time until your next birthday. All date computations are performed locally and accurately.
Koi Pond Stocking Calculator – Online Gallons per Fish
Enter pond dimensions and filtration type to estimate safe number of adult koi. Prevent overcrowding.
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.
Compound Interval Calculator - Online Daily/Weekly Growth
Compute compound interest with various compounding frequencies (daily, weekly, monthly). Compare APY with simple interest. Local and secure.
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.
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.
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.
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.
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.
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.
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.
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.
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.
Probability Calculator - Online Odds & Combinatorics Tool
Compute probability for simple events, as well as permutations and combinations (nPr, nCr). Useful for statistics and game theory. Browser-based math.
Tip Calculator - Online Free Gratuity & Bill Split Tool
Calculate tips and split bills easily. Adjust tip percentage and number of people. Perfect for dining out. All computations happen on your device.
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.
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.
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.
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.
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.
IQR Calculator - Online Interquartile Range & Box Plot
Enter a dataset to compute Q1, median, Q3, IQR, and highlight outliers. Visual box plot generated in canvas.
Bayes' Theorem Calculator - Online Probability Update Tool
Easily compute posterior probabilities given prior, likelihood, and marginal likelihood. Visual diagram. All local.
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.
Pythagorean Theorem Calculator - Online Right Triangle Solver
Enter two sides of a right triangle and get the third. Also gives area and perimeter. Simple and visual.
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.
Activity Calorie Burn Calculator - Online Exercise Estimator
Estimate calories burned for various activities like running, cycling, swimming based on duration and body weight. Informational and motivational.
Resistor Color Code Calculator - Online Band to Value
Select color bands to decode a resistor's value, tolerance, and temperature coefficient. Essential for anyone working with electronics hardware.
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.
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.
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.
Percentage Calculator - Online Find Percent, Increase & Decrease
Perform common percentage calculations: find percent of a number, percentage increase/decrease, and more. Simple, fast, and always available for free.
Candle Making Calculator - Online Wax & Fragrance Ratio
Calculate the exact amount of wax and fragrance oil needed based on container volume and desired scent load. DIY candle crafting.
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 Year Calculator - Online Ordinal Date
Find out what day number of the year any date is (1‑366). Also shows days remaining. Simple reference.
Running Splits Calculator - Online Race Pace Predictor
Enter a recent race time and predict times for other distances. Also get lap splits for different intervals.
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.
Soap Recipe Calculator - Online Lye & Oil Saponification
Create a custom soap recipe by selecting oils and their percentages. Get precise lye and water amounts. Safety warnings included.
Confidence Interval Calculator - Online Mean & Proportion
Compute confidence intervals for a population mean (known/unknown sigma) and proportion. All popular Z/T values. Local.
Poisson Distribution Calculator - Online Event Occurrence Probability
Compute Poisson probabilities for a given mean rate. Ideal for call centers, traffic analysis. Instant chart.
Aspect Ratio Calculator - Online 16:9 4:3 & Custom
Calculate new dimensions while preserving aspect ratio, or find the ratio from width and height. For video and images.
BMR Calculator - Online Basal Metabolic Rate & Calories
Calculate your Basal Metabolic Rate using the Mifflin‑St Jeor equation. Know how many calories you burn at rest. All data private.
Molar Mass Calculator - Online Molecular Weight Tool
Enter a chemical formula (e.g., H2O, C6H12O6) and calculate its molar mass. Handles parentheses and hydrates. Pure frontend.
Retirement Calculator - Online Savings & Investment Planner
Project your retirement savings growth with monthly contributions, employer match, and CAGR. Interactive chart. Financial data stays on your device.
Unit Price Calculator - Online Best Buy & Comparison Tool
Calculate the unit price of products to find the best deal. Compare multiple items at once. Perfect for grocery shopping and frugal living.
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.
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.
Children's BMI Calculator - Online Percentile & Growth
Calculate BMI for children and teens (ages 2‑19) and see the percentile based on CDC growth charts. Educational only.
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.
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.
Significant Figures Counter - Online Sig Fig Calculator
Count significant digits in a number and round to a specific number of sig figs. Perfect for chemistry and physics labs.
Run Pace Calculator - Online Min/Mile & Min/Km Splits
Calculate your running pace per mile/km, finish time for a race, and split times. Essential for runners.