ToolMars collection
Free Online Calculators – Finance, Health, Math & DIY
Finance, health, school math, and job-site estimators in one catalog. Start with the long-tail tools people actually search — bags of Quikrete per post, EMI, food cost — then browse the rest.
- Fence Post Concrete CalculatorFree fence post concrete calculator: how many bags of Quikrete per post hole. Enter hole size, post type, and bag weight for 40/50/60/80 lb bag counts, cost, and shopping list.
- Loan EMI CalculatorFree EMI calculator for home, car, and personal loans. Get monthly EMI, total interest, and amortization preview — private, no signup.
- Compound Interest CalculatorFree compound interest calculator with contributions. Project future value by compounding frequency, APY estimate, and interest earned — private, no signup.
- Mortgage CalculatorCalculate monthly mortgage payments, total interest, and a full amortization schedule instantly. Free tool with property tax estimates and CSV download.
- Hourly to Salary CalculatorFree hourly to salary converter (and reverse). Customize hours/week and weeks/year to see weekly, biweekly, monthly, and annual pay.
- Sales Tax CalculatorFree sales tax calculator: add tax to a price or reverse out pre-tax amount from a total. Instant tax math — private, no signup.
- Discount CalculatorFree discount calculator: find sale price from % off, calculate discount amount, or reverse-engineer original price and percent savings — shopping math made easy.
- Percentage CalculatorFree percentage calculator: find X% of Y, what percent A is of B, percentage increase/decrease, and reverse percentages — instant math, no signup.
- BMI CalculatorFree BMI calculator for adults. Enter height and weight in metric or imperial units to get BMI, category, and healthy weight range — private, no signup.
- Calorie CalculatorFree calorie calculator using Mifflin-St Jeor BMR and activity-based TDEE. See maintenance, loss, and gain calorie targets — private, no signup.
- A1C CalculatorConvert A1C (HbA1c) to estimated average glucose (eAG) in mg/dL or mmol/L, or reverse the calculation. Uses the ADA formula. Educational use only — not medical advice.
- Age CalculatorCalculate your exact age in years, months, days, and hours from any birth date. See total days lived, next birthday countdown, and age on past or future dates. Free tool.
- CGPA & GPA CalculatorFree CGPA calculator: enter courses, credit hours, and grades to get semester GPA and cumulative CGPA instantly. Private, browser-based, no signup.
- Semester Grade CalculatorCalculate your semester grade from weighted categories like homework, quizzes, and exams. Free, instant tool with letter grades and weight-sum warnings. No login.
- Square Footage CalculatorCalculate square footage instantly for rooms, flooring, and gardens. Free sq ft calculator with rectangle, circle, triangle shapes and waste factor.
- Gravel CalculatorFree gravel calculator: enter length, width, and depth to get cubic yards, tons, and cost estimates instantly. Perfect for driveways and landscaping.
- Cubic Feet CalculatorCalculate cubic feet from length, width, and height. Convert volume to cubic yards, US gallons, liters, and m³ instantly. Free online cubic feet calculator.
- Board Foot CalculatorCalculate board feet from lumber thickness, width, length, and quantity. Free instant board foot calculator with cubic feet conversion for woodworking.
- Markup CalculatorFree markup calculator: find selling price from cost and markup %, or reverse-calculate profit and margin. Instant results for retail and wholesale pricing.
- Dividend CalculatorCalculate dividend income and yield from shares, dividend per share, and stock price. Free instant estimates for annual, quarterly, and monthly payouts.
- Trading P&L CalculatorCalculate average cost basis, net profit, ROI, and capital gains for stocks and crypto. Free instant P&L tool with exchange fees and tax estimates.
- Rounding CalculatorRound numbers to decimal places, significant figures, or nearest step instantly. Free rounding calculator for math, science, and everyday estimates.
- Variance CalculatorCalculate variance, standard deviation, mean, and sum of squares from any number list. Switch between population (n) and sample (n−1) mode. Free statistics tool.
- Mean Median Mode CalculatorFind mean, median, mode, range, min, and max from any number list. Paste comma-separated values and get instant statistics. Free online tool for homework and data.
- Mixed Number CalculatorConvert mixed numbers to improper fractions and back, or add, subtract, multiply, and divide instantly. Free mixed number calculator with decimal results.
- Proportion CalculatorSolve a/b = c/d for any missing value using cross-multiplication. Find unknown numerators or denominators and check equivalent ratios. Free proportion calculator.
- Percent Error CalculatorCalculate percent error, absolute error, and relative error instantly. Free calculator for chemistry, physics lab reports, and science homework.
- Steps to Miles CalculatorConvert steps to miles or miles to steps using custom stride length or height-based estimates. Free, instant calculator with km and calorie estimates. No signup.
- Calculator WatchUse a free four-function calculator with a digital watch look. Add, subtract, multiply, divide, and percent — instant results in your browser.
Looking for something else? Browse all 54 tools.