CalculatorPod provides 114 free formula calculators that you can use directly in your browser — no login, no app download, no cost. Each tool is built with accurate, formula-driven logic and instant results so you can get answers in seconds.

All calculators tagged formula are optimised for both desktop and mobile, and include step-by-step explanations, worked examples, and FAQs to help you understand the numbers - not just the answer.

Calculators in This Collection

Area Calculator - Calculate area and perimeter for 8 shapes: rectangle, triangle, circle, trapezoid, parallelogram, ellipse, sector, and polygon. Free, instant, all formulas shown.
BMI Calculator: Body Mass Index - Calculate your Body Mass Index with full WHO classification (8 categories). See BMI Prime, Ponderal Index, healthy weight range, and weight to target. Free.
CAGR Calculator: Compound Annual Growth Rate - Calculate CAGR (Compound Annual Growth Rate) for any investment. Find annualized return, ending value, or years needed. Shows total return, gain, and doubling time. Free.
Decimal to Percent Converter - Convert any decimal to a percentage or any percentage to a decimal instantly. See the fraction and ratio form too. Free, instant, no signup required.
Graphing Quadratic Inequalities Calculator - Solve any quadratic inequality ax²+bx+c > 0, < 0, ≥ 0, or ≤ 0. Get roots, solution set, and interval notation instantly. Free step-by-step solver.
Grouped Data Standard Deviation Calculator - Calculate mean, population SD, sample SD, variance, and CV from grouped frequency data. Enter up to 10 class midpoints and frequencies. Free, instant.
Interest-Only Mortgage Calculator - Compare your interest-only mortgage payment to a conventional payment. See the post-IO amortizing jump, total interest cost, and exactly how much extra IO costs long-term.
Lottery Tax Calculator - Calculate exactly how much of your lottery winnings you keep after federal and state taxes. Lump sum vs annuity, all 50 states. Free, instant, 2025 rates.
Matthews Correlation Coefficient Calculator - Calculate MCC from a confusion matrix or raw labels. Outputs accuracy, precision, recall, F1, specificity, balanced accuracy, and Cohen's kappa. Free.
Mean Calculator - Calculate arithmetic, geometric, harmonic, and quadratic mean from any dataset. Also compute weighted mean with custom weights. Free, instant results.
MIRR Calculator - Modified Internal Rate of Return - Calculate Modified Internal Rate of Return (MIRR) for any investment. Set finance and reinvestment rates separately. Compare with IRR and hurdle rate. Free.
NPV Calculator: Net Present Value - Calculate Net Present Value of any project or investment. Enter initial cost, discount rate, and annual cash flows to get NPV, profitability index, and accept/reject signal. Free.
Percentage Increase Classic - Classic percentage increase formula: enter old and new values to get % increase, absolute increase, and growth multiplier. Free, instant, no signup.
Relatively Prime Calculator - Check if two integers are relatively prime (coprime). Shows GCF, Euclidean algorithm steps, prime factorizations, and all common divisors. Free, instant.
Right Triangle Side and Angle Calculator - Solve any right triangle: find all sides and angles from two known values. Four input modes, all six trig ratios, area, perimeter, and altitude to hypotenuse.
ROI Calculator: Return on Investment - Calculate Return on Investment as a percentage, net profit or loss, annualized return (CAGR), and investment multiple for any asset or project. Free, instant, no signup.
Sales Tax Calculator New Jersey - Calculate NJ sales tax instantly. Standard 6.625% rate or Urban Enterprise Zone 3.3125% rate. Add tax to a price or remove it from a total. Free, instant.
Special Right Triangles Calculator - Calculate all sides, area, and perimeter of 45-45-90 and 30-60-90 special right triangles from any one known side. Free, instant, with exact ratios.
BMI Calculator for Teens - Calculate BMI for teenagers aged 10-19 using CDC growth chart percentiles. See if your teen is underweight, healthy, overweight, or obese. Free tool.
Calories Burned by Heart Rate Calculator - Calculate calories burned during exercise from your average heart rate, age, weight, and duration using the Keytel formula. Free, instant results.
Mortgage Calculator with Taxes and Insurance - Calculate your full monthly mortgage payment including principal, interest, property taxes, homeowners insurance, HOA, and PMI. Free PITI calculator.
Mortgage Prepayment Calculator - Calculate how much interest you save and time you cut by making a lump-sum or extra monthly mortgage prepayment. Free, instant results.
State Tax Calculator - Calculate state income tax for all 50 US states and DC. See your effective rate, marginal rate, and take-home pay for 2025. Free, instant results.
Acceleration Calculator - Calculate acceleration, final velocity, or time using a = (v-u)/t. Instant results in m/s², g-force, and ft/s². Free online physics calculator with worked examples.
ARM Mortgage Calculator - Calculate your ARM mortgage payment for the fixed period and after adjustment. Compare initial vs adjusted payments, see balance at reset, and max payment at cap.
BAC Calculator - Blood Alcohol Content - Estimate your blood alcohol content using the Widmark formula. Enter weight, drinks, and hours to see BAC level, impairment category, and hours to sober. Free.
Dosage Calculator - Calculate medication dose by weight using mg/kg. Get single dose in mg, suspension volume in mL, daily total, and doses per day for any frequency. Free, instant.
GCF and LCM Calculator - Find the GCF and LCM of 2 to 8 numbers simultaneously. Shows prime factorizations, Euclidean algorithm steps, and the relationship GCF × LCM = a × b.
Kinetic Energy Calculator - Calculate kinetic energy, mass, or velocity using KE = 0.5mv². Results in joules, kJ, kcal, kWh, BTU, and ft·lbf. Free online physics calculator with examples.
Quadratic Formula Calculator - Solve any quadratic equation ax²+bx+c=0 instantly. Shows discriminant, real and complex roots, vertex, axis of symmetry, and full step-by-step working. Free.
Velocity Calculator - Calculate speed, distance, or time using v = d/t. Instant conversions between m/s, km/h, mph, and ft/s. Free online velocity calculator with worked examples.
Annual Income Calculator - Convert hourly, daily, weekly, biweekly, monthly, or quarterly pay to annual income instantly. Combine multiple income sources to find your total yearly earnings.
Area of a Circle Calculator - Calculate the area, circumference, and diameter of any circle from its radius, diameter, or circumference. Shows formula and step-by-step working. Free.
Biweekly Mortgage Calculator - Calculate how much interest you save and how many years you cut by switching to biweekly mortgage payments. Free biweekly payment calculator with full comparison.
Blood Pressure Calculator - Enter your systolic and diastolic reading to get your AHA 2017 blood pressure category, Mean Arterial Pressure, Pulse Pressure, and recommended next steps. Free.
Break-Even Calculator - Calculate break-even units and revenue instantly. Enter fixed costs, variable cost per unit, and selling price to find your break-even point. Free online tool.
California Tax Calculator - Calculate your California state income tax, federal tax, SDI, and FICA for 2025. See your total tax burden, effective rate, and net take-home pay. Free, instant.
Circumference Calculator - Calculate the circumference of any circle from its radius, diameter, or area. Shows formula and all related circle properties. Free, instant, no signup.
Combination Calculator - Calculate combinations C(n,r) instantly. Enter n and r to get the count of unordered selections, full step-by-step expansion, and list all combos for small sets. Free.
Conception Calculator - Calculate your estimated conception date from a due date or last menstrual period. Shows fertile window, gestational age, trimester, and days to EDD. Free.
Discount Rate Calculator - Calculate discount rate from any present value and future value, or find the present value of any future cash flow. Free, instant, multi-currency online tool.
Down Payment Calculator - Calculate the down payment for any home price, see how long to save based on current savings and monthly contributions, and check PMI status. Free, instant.
Factorial Calculator - Calculate n! factorial, nPr permutations, and nCr combinations instantly. Shows step-by-step expansion. Free online math tool for students and teachers.
Future Value Calculator - Calculate future value, present value, interest rate, or time for any investment. Full time value of money solver. Free, instant, no signup.
GCF Calculator (Greatest Common Factor) - Find the greatest common factor (GCF) of 2-8 numbers instantly. Shows Euclidean algorithm steps and prime factorizations. Free online GCF and LCM tool.
Home Affordability Calculator - Find out how much house you can afford based on income, debts, and down payment. Calculates max home price, loan amount, PITI, and debt-to-income ratio. Free.
Investment Calculator - Calculate future value of lump sum or monthly investments. See total gains, growth %, and year-by-year table. Free online investment return calculator.
LCM Calculator (Least Common Multiple) - Find the least common multiple (LCM) of 2-8 numbers instantly. Shows step-by-step calculation and prime factorizations. Free online LCM and GCF tool.
Maintenance Calorie Calculator - Calculate your maintenance calories (TDEE) instantly. Enter age, weight, height, and activity level to find exactly how many calories you need to maintain your weight.
Mortgage Rate Calculator - Calculate your mortgage payment at any interest rate, or find the exact rate you need to hit a target monthly payment. Free, instant, multi-currency.
New York Tax Calculator - Calculate your New York State income tax, NYC city tax, federal tax, and FICA for 2025. See your full tax burden, effective rates, and net take-home pay. Free, instant.
Overtime Calculator - Calculate overtime pay for any pay period or project annual earnings with regular overtime. Supports time-and-a-half, double-time, and custom multipliers. Free.
Permutation Calculator - Calculate permutations P(n,r) instantly. Enter n and r to get ordered arrangements, step-by-step expansion, and list all arrangements for small inputs. Free.
Present Value Calculator - Calculate present value of a lump sum, ordinary annuity, annuity due, or perpetuity. Full PV formula with discount, EAR, and total payment breakdown.
Savings Calculator - Calculate how your savings grow over time. Enter initial deposit, monthly contribution, interest rate, and years to see total savings and interest earned. Free.
Standard Form Calculator - Convert any number to standard form (scientific notation) instantly. Enter a number to get A x 10^n, or convert from standard form back to decimal notation.
Texas Tax Calculator - Calculate federal income tax and FICA for Texas 2025 residents. See net take-home, property tax estimates, and savings vs. California and New York. Free.
VA Loan Calculator - Calculate your VA loan monthly payment including P&I, VA Funding Fee, property tax, and insurance. Free VA mortgage calculator for veterans and service members.
BMI Calculator for Kids - Calculate your child's BMI and CDC percentile category (ages 2-19). See if your child is underweight, healthy, overweight, or obese using CDC growth charts. Free.
BMI Calculator for Men - Calculate BMI for men with estimated body fat percentage using the Deurenberg formula. See WHO categories, healthy weight range, and weight targets by height. Free.
BMI Calculator for Women - Calculate BMI for women with estimated body fat percentage using the Deurenberg formula. See WHO categories, healthy weight range, and weight targets by height. Free.
BMR Calculator - Basal Metabolic Rate (Mifflin-St Jeor Equation) - Calculate your Basal Metabolic Rate using the Mifflin-St Jeor equation. Get BMR, TDEE, and calorie targets for any goal. Compare with Harris-Benedict. Free.
Correlation Coefficient Calculator - Calculate Pearson r, R2, regression equation, t-statistic, and p-value from raw data pairs or summary statistics. Shows interpretation. Free, instant.
FICA Tax Calculator - Calculate your 2025 FICA taxes: Social Security (6.2%), Medicare (1.45%), and Additional Medicare (0.9%). Covers employees and self-employed - free, instant.
Normal Distribution Calculator - Calculate normal distribution probabilities: P(X<x), P(X>x), P(a<X<b), z-scores, and inverse CDF. Enter mean, standard deviation, and x. Free, instant.
Percentile Calculator - Find percentile rank of any value in a dataset, or find the value at any percentile. Shows Q1, Q2, Q3, IQR, and sorted list. Free, instant.
Sample Size Calculator - Calculate the required sample size for surveys (proportion) or experiments (mean) at any confidence level and margin of error. Includes FPC. Free, instant.
Tax Bracket Calculator - Calculate your 2025 US federal income tax bracket, marginal rate, effective rate, and exact tax owed. Compare all four filing statuses instantly - free.
TDEE Calculator - Total Daily Energy Expenditure - Calculate your Total Daily Energy Expenditure (TDEE) using Mifflin-St Jeor or Harris-Benedict BMR formula. Get calorie targets for any goal - free, instant.
Variance Calculator - Calculate sample variance, population variance, and standard deviation from a dataset or grouped frequency table. Shows deviation table. Free, instant.
FHA Loan Calculator - Calculate your FHA loan monthly payment including P&I, upfront MIP, annual MIP, taxes, and insurance. Free FHA mortgage calculator with full payment breakdown.
Home Mortgage Calculator - Calculate your complete monthly mortgage payment including P&I, property tax, insurance, and PMI. Free home mortgage calculator with amortization table.
Hourly to Salary Calculator - Convert hourly wage to annual salary, monthly, biweekly, and weekly pay instantly. Includes an overtime calculator with time-and-a-half - free online tool.
Mortgage Amortization Calculator - Generate a full mortgage amortization schedule with monthly and yearly views. See how extra payments reduce interest and shorten your loan term. Free.
Mortgage Payoff Calculator - Calculate how extra monthly mortgage payments cut your payoff date and total interest. Enter balance, rate, term and see months saved instantly - free.
Mortgage Refinance Calculator - Calculate if refinancing your mortgage makes sense. Compare current vs new payment, monthly savings, break-even period, and total interest saved after closing costs.
Salary Calculator - Convert annual salary to hourly, daily, weekly, and monthly rates. Estimate US take-home pay after federal tax, FICA, state tax, and 401k deductions - free.
Salary to Hourly Calculator - Convert annual or monthly salary to an hourly rate instantly. See your effective hourly wage at any hours-per-week assumption - free online calculator.
Absence Percentage Calculator - Calculate employee absence rate as a percentage of total working days. Also computes the Bradford Factor for measuring impact of short-term absences. Free HR calculator.
Compound Interest Rate Calculator - Find the compound interest rate or time period needed to grow an investment. Two modes: solve for annual rate r, or solve for time t. Supports all compounding frequencies.
Median Absolute Deviation Calculator - Calculate the Median Absolute Deviation (MAD) of any dataset. Enter comma-separated numbers to get MAD, normalized MAD (σ̂), median, SD comparison, and a full deviation table with outlier flags.
MSE Calculator - Calculate Mean Squared Error (MSE), Root Mean Squared Error (RMSE), and Mean Absolute Error (MAE) for any set of actual vs predicted values. Free online tool.
Perimeter of a Triangle Calculator - Calculate the perimeter of any triangle from three sides, two sides and an angle, or base and height. Also shows area, triangle type, and all angles. Free tool.
Pooled Standard Deviation Calculator - Calculate the pooled standard deviation for two or more groups. Enter summary stats (n, SD) or raw data. Shows pooled SD, pooled variance, degrees of freedom, and per-group breakdown.
Relative Standard Deviation Calculator - Calculate Relative Standard Deviation (RSD) and Coefficient of Variation (CV) for any dataset. Enter numbers and get RSD%, mean, standard deviation, and variance instantly.
Similar Triangles Calculator - Find missing sides of similar triangles using proportional ratios. Enter three sides of Triangle 1 and one or two sides of Triangle 2. Shows scale factor and area ratio.
Triangle Angle Calculator - Find all three angles of any triangle from its side lengths using the Law of Cosines. Also classifies triangle type and shows perimeter. Instant results.
Business Loan Calculator - Calculate business loan EMI, total interest, and repayment schedule instantly. Supports any loan amount, interest rate, and tenure up to 30 years. Free online tool.
IRR Calculator - Calculate the Internal Rate of Return (IRR) for any investment or project with up to 15 cash flows. Compare IRR to hurdle rate to make smarter capital decisions.
Median Calculator - Find the median of any dataset instantly. Enter numbers separated by commas or spaces. Also shows mean, mode, range, min, max, and sorted list. Free online tool.
Pythagorean Theorem Calculator - Calculate the missing side of a right triangle using the Pythagorean theorem. Find hypotenuse, missing leg, or verify a Pythagorean triple instantly.
Right Triangle Calculator - Calculate all sides, angles, area, and perimeter of a right triangle. Three modes: two legs, hypotenuse + one leg, or angle + one side. Instant results.
Average Percentage Calculator - Calculate the average of percentages correctly. Simple mode averages a list of percentages. Weighted mode computes the true weighted average using population sizes. Free.
Doubling Time Calculator - Calculate how long it takes an investment, population, or any value to double at a given growth rate. Exact compound formula and Rule of 72 approximation. Free.
Geometric Mean Calculator - Calculate the geometric mean of any set of values. Includes CAGR mode for investment growth rates. Shows arithmetic and harmonic mean for comparison. Free, instant.
Harmonic Mean Calculator - Calculate the harmonic mean of any set of values. Includes average speed mode for round-trip journeys. Shows arithmetic and geometric mean for AM-GM-HM comparison. Free.
Percent Error Calculator - Calculate percent error between a measured (experimental) value and the true (actual) value. Instant formula, worked examples, and science/lab use cases. Free.
Percentage Decrease Calculator - Calculate the percentage decrease from one value to another instantly. Find the new value after a % decrease or reverse-calculate the original. Free, no signup.
Percentage Difference Calculator - Calculate the percentage difference between two values symmetrically. Unlike percentage change, percentage difference has no reference direction. Free, instant.
Percentage Increase Calculator - Calculate percentage increase between two values instantly. Find new value after a % increase or reverse-calculate the original. Free, instant, no signup.
Percentage Point Calculator - Calculate the difference between two percentages in percentage points. Understand the critical difference between percentage points and percent change. Free calculator.
Root Mean Square Calculator - Calculate the root mean square (RMS) of any set of values. Includes AC voltage mode: find RMS voltage from peak voltage. Shows mean, standard deviation, and sum of squares. Free.
Weighted Average Calculator - Calculate weighted average for any values and weights. Includes CGPA calculator mode for Indian grading systems. Shows full breakdown table. Free, instant.
Confidence Interval Calculator - Calculate confidence intervals for population means and proportions at 90%, 95%, or 99% confidence levels. Shows margin of error, z-score, and full formula.
Electricity Bill Calculator - Calculate your electricity bill from units consumed and tariff rate. Add fixed charges and taxes. Estimate monthly and annual costs instantly. Free online tool.
Ellipse Calculator - Calculate ellipse area, perimeter (circumference), eccentricity, foci distance, and semi-latus rectum from semi-major and semi-minor axes. Free online tool.
Parallelogram Calculator - Calculate area, perimeter, height, and diagonals of a parallelogram. Supports base-height, base-side-angle, and diagonal modes. Free, instant results.
Percentage Change Calculator - Calculate percentage change, increase, or decrease between two values instantly. Shows direction, formula, and absolute difference. Free, no signup required.
Permutation & Combination Calculator - Calculate permutations nPr and combinations nCr instantly. Enter n and r to get results with step-by-step factorial breakdown. Free online tool.
Half-Life Calculator - Calculate half-life, decay constant λ, and mean lifetime τ from any one value. Includes common isotope reference table. Free nuclear physics calculator.
Nuclear Binding Energy Calculator - Calculate nuclear binding energy from mass defect using E=Δmc². Get total binding energy in MeV and binding energy per nucleon. Free nuclear physics calculator.
Nuclear Fission Energy Calculator - Calculate nuclear fission Q-value from reactant and product atomic masses. Get energy per fission in MeV and joules, and per gram/kg of fissile material. Free.
Radiation Dose Calculator - Convert absorbed dose (Gy) to equivalent dose (Sv) using ICRP radiation weighting factors. Calculate effective dose by tissue type. Free radiation dose calculator.
Radioactive Decay Calculator - Calculate remaining nuclei, activity, and fraction decayed using N=N₀e^(−λt). Enter half-life or decay constant. Free radioactive decay calculator.

How to Use These Calculators

Every calculator on CalculatorPod follows a consistent three-step pattern:

Enter your values - fill in the input fields. Each field has a label and a sensible default so you can start immediately.
Click Calculate - results appear instantly without a page reload. No waiting.
Read the breakdown - results are accompanied by a formula explanation and a worked example so you can verify the logic yourself.

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Why Use CalculatorPod?

CalculatorPod is a free, no-signup calculator platform covering finance, math, health, science, engineering, and everyday use. Every calculator is hand-built with verified formulas - not generated approximations - and cross-checked against standard references.

Unlike generic formula pages, each CalculatorPod calculator is interactive: enter real numbers and see real results instantly. The formulas and worked examples alongside each tool mean you understand why the answer is what it is.