How to choose a calculator
Start with the real need: convert a unit, estimate a cost, compare two scenarios or verify a formula. Then open the tool whose fields match your data without mixing periods, currencies or units.
Free tools
All calculators
Browse every Calcunia calculator by category: finance, math, health, business, conversions, real estate and more.
Calcunia method
What you can verify
Why the directory is limited
This page highlights reviewed core calculators. Unvalidated programmatic pages are kept out of the public directory and the standard sitemap so the visible set remains useful, readable and checkable.
Estimator, converter or formula
A converter changes a value between units, an estimator projects a result from assumptions, and a financial calculator often depends on a rate, duration and schedule. This distinction helps you read the output correctly.
Check the assumptions
Before comparing two results, confirm that values use the same period, currency, perimeter and unit system. A correct formula can still lead to a weak conclusion when the inputs describe different situations.
Read each tool’s limits
Each important page should explain what is not included: fees, taxes, inflation, rounding, edge cases, local rules or professional context. This prevents an exact-looking number from being overread.
Check before deciding
For an important decision, compare several scenarios, review rounding and read the limitations shown on the calculator page. The result is a calculation aid, not personalized professional advice.
Tools to explore
Compound Interest
Project your future wealth through disciplined contribution and time.
Simple Interest
Calculate uncompounded interest earned or paid on a principal sum over time.
Savings Goal
Calculate the monthly contribution required to reach your savings goal, visualize capital growth, and compare realistic optimization scenarios.
Future Value
Calculate future value from capital, rate, duration and compounding frequency, with interest earned and growth scenarios.
Loan Amortization
Visualize periodic payments and the total cost of debt over time.
ROI Calculator
Analyze the total profitability and yield of capital investments.
CAGR Calculator
Compute the smoothed annualized yield of an investment over a specified duration.
Rule of 72
Instantly estimate how long it takes for a fixed-rate investment to double in value.
Livret A Simulator 2026
Calculate how your French Livret A savings account grows based on your initial capital, monthly deposits and duration. 2026 rate: 2.5%. Cap: €22,950.
Borrowing Capacity Calculator
Estimate your mortgage borrowing capacity based on income, existing debt, rate and duration. HCSF rule: debt ratio ≤ 35%.
Retirement Savings Simulator
Project your retirement capital based on age, contributions and expected return. Compare it with the capital needed for your target pension.
Inflation Calculator
Calculate the impact of inflation on money: future cost, remaining purchasing power, real loss and scenarios over 5, 10, 20 or 30 years.
APR Calculator (TAEG)
Calculate the real cost of your loan with APR: payment, interest, insurance, application fees, guarantee costs, amortization table and scenario comparison.
Debt Payoff Calculator
Plan the payoff order for several debts with avalanche, snowball or balanced strategy, extra payment, charts, schedule, total interest and debt-free date.
Mortgage Refinance Calculator
Compare your current mortgage with a refinance scenario: payment, real savings, fees, insurance, estimated APR, term change and break-even point.
Credit Card Payoff Calculator
Simulate credit card payoff time: minimum payment, fixed payment, accelerated payment, interest, fees, payoff date and potential savings.
Emergency Fund Calculator
Calculate the ideal safety reserve from essential expenses, risk profile, income stability and target months of coverage.
Investment Fee Calculator
Measure the real impact of fees on investment growth: entry fees, management fees, exit fees, inflation, net return and final value after costs.
Dividend Yield Calculator
Calculate dividend yield for a stock: gross annual income, net income after estimated tax, yield on cost, projection, reinvestment and required capital.
Dollar Cost Averaging Calculator
Simulate recurring investments: total invested, accumulated units, average cost, projected value, potential gain, fees, inflation and return scenarios.
Net Worth Calculator
Calculate net worth with assets, debts, real estate, savings, investments, debt ratio, liquidity, productive assets and wealth projection.
Real Return Calculator
Calculate real return after inflation, fees and recurring contributions: nominal value, real value, purchasing power, cumulative inflation and scenarios.
Retirement Withdrawal Calculator
Simulate retirement savings withdrawals with available capital, monthly income, inflation, fees, tax estimate, portfolio duration and prudent scenarios.
Percentage Calculator
Quick and precise calculations for margins, changes, and ratios.
Rule of Three
Solve for variables through direct mathematical proportion.
Fraction Calculator
Add, subtract, multiply and divide fractions with a simplified result.
Ratio Calculator
Compare two quantities, simplify A:B, convert the ratio to percentages and scale it to a real total.
Average Calculator
Calculate a simple or weighted average, inspect coefficients, median, spread, contribution and distribution charts.
Percentage Change Calculator
Calculate an increase, decrease, absolute delta, multiplier and target gap between an initial and final value.
Discount Calculator
Calculate a final price after discount, promo code, tax, fees and quantity, then compare real savings scenarios.
Tip Calculator
Calculate a tip, taxes, fees, total with tip and per-person share for restaurants, delivery or shared bills.
Scientific Notation Converter
Convert numbers between standard, scientific and engineering notation with mantissa, exponent and significant digits.
Probability Calculator
Calculate simple, conditional, union, intersection and complement probabilities with fractions, percentages, odds and expected frequency.
BMI Calculator
Calculate BMI, identify the adult category and complete the reading with healthy weight range, waist measurement, activity and indicator limits.
BMR Calculator
Estimate resting energy needs, compare activity levels and turn this benchmark into maintenance, weight-loss or lean-gain targets.
Daily Calories
Calculate daily calories by age, height, weight, sex, activity and goal. Estimate BMR, TDEE, maintenance, weight loss, lean gain and macronutrients.
Due Date Calculator
Calculate your estimated due date from the last period, conception or ultrasound. Follow pregnancy weeks, trimester, remaining days and key milestones.
Ideal Weight Calculator
Estimate a reference weight range from height, profile, morphology and goal. Compare Lorentz, Devine, Creff and the healthy BMI range without reducing the result to a single number.
Body Fat Percentage Calculator
Estimate body fat percentage with US Navy, Deurenberg and BMI-based methods. Compare fat mass, lean mass, category, target zone and trend.
Water Intake Calculator
Calculate daily water needs by weight, age, activity, climate and exercise. Estimate liters per day, glasses, bottles, hourly plan and hydration tips.
Protein Intake Calculator
Calculate protein needs by weight, activity and goal. Estimate grams per day, g/kg, protein per meal, optimal range and food equivalents.
Target Heart Rate Calculator
Calculate target heart rate from age, resting HR, intensity and the Karvonen method. Get cardio zones, bpm, max HR, reserve HR and training tips.
Calories Burned Calculator
Calculate calories burned by activity, weight, duration and intensity. Estimate kcal, MET, calories per minute, weekly projection, cardio zones and activity comparison.
Macro Calculator
Calculate macronutrients by calories, weight, activity and goal. Estimate protein, carbs, fat, grams per meal, ratios, scenarios and food equivalents.
Calorie Deficit Calculator
Estimate maintenance calories, daily deficit, target intake, macronutrients and a weekly weight-loss projection.
Pregnancy Weight Gain Calculator
Place pregnancy weight gain in context by pre-pregnancy BMI, week, trimester and pregnancy type with a cautious reading.
Ovulation Calculator
Estimate ovulation date, fertile window, most favorable days, next period and key cycle phases with cautious interpretation.
Sleep Cycle Calculator
Calculate an ideal bedtime or wake-up time from complete cycles, sleep latency, sleep duration and recovery goal.
Waist-to-Hip Ratio Calculator
Calculate waist-to-hip ratio, compare ranges, understand your result and learn how to measure waist and hips correctly.
Running Calorie Calculator
Calculate calories burned while running from distance, duration, pace, body weight, terrain and intensity with charts, zones and advice.
Cycling Calorie Calculator
Calculate calories burned while cycling from duration, distance, speed, body weight, bike type, terrain and intensity with charts, zones and advice.
BAC Calculator
Estimate blood alcohol level cautiously from drinks, drinking duration, body weight and profile with clear safety reminders.
Daily Step Goal Calculator
Set a realistic daily step goal from your current average, available walking time and sustainable weekly progression.
Unit Converter
Convert measurements between metric and imperial systems: length, mass, volume, temperature, area and speed.
Length Converter
Convert meters, centimeters, millimeters, kilometers, inches, feet, yards and miles with visible factors.
Weight / Mass Converter
Convert kilograms, grams, milligrams, tonnes, pounds, ounces and stones with visible factors.
Volume Converter
Convert liters, milliliters, centiliters, cubic meters, US gallons, imperial gallons, cups, pints and fluid ounces with clear factors.
Area Converter
Convert square meters, square centimeters, square millimeters, hectares, acres, square feet and square inches with clear factors.
Temperature Converter
Convert Celsius, Fahrenheit, Kelvin, Rankine and Réaumur with formulas and practical references.
Speed Converter
Convert km/h, m/s, mph, knots, ft/s and Mach with formulas and practical references.
Pressure Converter
Convert pascals, bars, PSI, atmospheres, mmHg, kPa and MPa with formulas and practical references.
Data Storage Converter
Convert bits, bytes, KB, MB, GB, TB, KiB, MiB, GiB and TiB with decimal and binary references.
Kitchen Mass-Volume Converter
Convert grams, milliliters, cups, spoons, ounces and pounds by ingredient with density, tables and recipe examples.
Energy Converter
Convert kWh, joules, Wh, MJ, kcal, BTU, thermies and electronvolts with a table, formulas, indicative cost and practical references.
Shoe Size Converter
Convert EU, UK, US men, US women, centimeters and inches with a table, foot measurement guide, fit advice and purchase currency.
Clothing Size Converter
Convert FR, EU, US, UK, international sizes and body measurements with a table, fit guide, cm measurements and purchase currency.
Profit Margin Calculator
Calculate net profit margin from revenue, cost of goods sold, fixed costs, variable expenses, discounts and profitability scenarios.
Markup Rate Calculator
Calculate markup rate, gross margin, unit profit and recommended selling price from costs, discounts, VAT and volume.
Gross Profit Calculator
Calculate gross profit, gross margin, direct costs, profit per unit and scenarios from revenue, cost, discount and volume.
CPM Calculator
Calculate cost per thousand impressions and analyze advertising campaigns with budget, impressions, clicks and conversions.
VAT Calculator
Extract or append consumption taxes for accurate commercial invoicing.
Break-Even Point
Determine the exact sales volume required to cover all fixed and variable costs.
Salary Converter
Translate gross compensation across hourly, monthly, and annual formats.
Recipe Scaler
Resize ingredient quantities from one serving size to another.
Paint Calculator
Estimate wall area and the amount of paint needed for a room.
Grade Average
Calculate a weighted average from several grades and coefficients.
Duration Calculator
Convert days, hours, minutes and seconds into total duration units.
Fuel Cost Calculator
Estimate fuel required and trip cost from distance, consumption and fuel price.
Electricity Cost
Calculate electricity use, kWh cost, peak/off-peak split and monthly or yearly projection for an appliance.
Download Time
Estimate how long a file download takes from file size and connection speed.
Density Calculator
Calculate density from mass and volume for science and lab exercises.
Travel Budget
Estimate a complete travel budget with accommodation, meals, transport, activities, daily cost, currency and contingency buffer.
Income Tax Calculator 2026
Estimate 2026 French income tax from 2025 income, family situation, tax shares, deductible expenses, tax credits and effective rate.
Rental Yield
Estimate the real performance of a rental investment with gross yield, net yield, cash flow, expenses, loan, vacancy and scenarios.