Free Online Tools
46 calculatorsFree Online Calculators
Financial, health, and date calculators — all free, instant, no account needed.
Every calculator runs entirely in your browser — results are instant, private, and require no account. Whether you're planning a mortgage, tracking your BMI, estimating retirement savings, calculating fuel costs, or counting days from today — each tool gives you a clear, accurate answer in seconds using standard formulas.
Financial Calculators
Mortgage Calculator
Estimate your monthly mortgage payment and total cost.
OpenLoan Calculator
Calculate payments for any type of personal or business loan.
OpenAuto Loan Calculator
Find your monthly car payment and total loan cost.
OpenPersonal Loan Calculator
Plan repayments for personal loans at any interest rate.
OpenCredit Card Payoff Calculator
See exactly how long until your credit card is paid off.
OpenDebt Payoff Calculator
Map your debt-free date using avalanche or snowball strategy.
OpenRefinance Calculator
Compare your current loan against a new refinance rate.
OpenAmortization Calculator
View your full loan payment schedule month by month.
OpenInvestment Calculator
Project returns on any investment over time.
OpenRetirement Calculator
Estimate how much you need to retire comfortably.
OpenCompound Interest Calculator
See how compound interest grows your savings over time.
OpenInflation Calculator
Understand the real purchasing power of money over time.
OpenSalary Calculator
Convert between hourly, weekly, monthly, and annual pay.
OpenMonthly Budget Planner
Plan your monthly income and expenses with ease.
OpenSavings Goal Calculator
Find out exactly when you'll reach any savings target.
OpenExpense Splitter
Fairly split shared costs between any number of people.
OpenSales Tax Calculator
Quickly add or remove sales tax from any amount.
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Health & Lifestyle
BMI Calculator
Check your Body Mass Index and healthy weight range.
OpenCalorie Calculator
Find your daily calorie needs for weight loss, gain, or maintenance.
OpenBody Fat Calculator
Estimate your body fat percentage accurately.
OpenPregnancy Calculator
Calculate your due date and key pregnancy milestones.
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Date & Age
Age Calculator
Find your exact age in years, months, days, and hours from your date of birth.
OpenDate to Date Calculator
Count days, working days, weeks, and months between two dates.
OpenDate Difference Calculator
Find the exact number of days, weeks, months, and years between any two dates.
OpenDays From Today Calculator
Find the exact date that is N days from today — instantly.
OpenDays Ago Calculator
Find the exact date that was N days ago from today.
OpenAdd or Subtract Days from a Date
Add or subtract any number of days from any starting date to find the resulting date.
OpenBusiness Days Calculator
Add or subtract business days (Mon–Fri) from any date, skipping weekends.
OpenWorkdays Between Two Dates
Count the exact number of working days (Monday–Friday) between any two dates.
OpenCountdown Timer
Count down the days, hours, minutes, and seconds to any future date or event.
OpenDay of the Week Calculator
Find what day of the week any date falls on — past or future.
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Automotive
Fuel Cost Calculator
Estimate the fuel cost for any trip based on distance, fuel efficiency, and manual fuel price input.
OpenFuel Economy Calculator
Calculate your vehicle's fuel economy in MPG, L/100km, or km/L from distance and fuel used.
OpenCost Per Mile / km Calculator
Find your true cost per mile or kilometer driven, including fuel, insurance, maintenance, and depreciation.
OpenCar Depreciation Calculator
Calculate how much your car loses in value over time using a custom annual depreciation percentage.
OpenTire Size Calculator
Decode any tire size code and get diameter, width, sidewall height, and circumference.
OpenTire Comparison Calculator
Compare two tire sizes side-by-side: diameter difference, speedometer error, and fitment guidance.
OpenSpeedometer Error Calculator
Calculate how different tire sizes affect your speedometer and odometer readings.
OpenEV Charging Time Calculator
Estimate how long it takes to charge your electric vehicle based on battery capacity and charger power.
OpenTowing Capacity & Payload Calculator
Check if your vehicle can safely tow a trailer by calculating tongue weight, payload, and remaining capacity.
OpenWheel Offset Calculator
Calculate wheel backspacing and determine how a new offset affects wheel position and clearance.
OpenEngine RPM Calculator
Calculate engine RPM from vehicle speed, gear ratio, and tire size — or find your speed at any RPM.
OpenHorsepower to Weight Ratio
Calculate your car's power-to-weight ratio in hp/lb and hp/ton for a quick performance benchmark.
OpenTop Speed & 0–60 Estimator
Estimate your car's theoretical top speed and 0–60 mph time from horsepower, weight, and drag.
OpenBrake Pad Life Calculator
Estimate how many miles remain on your brake pads based on wear percentage and driving habits.
OpenOil Change Interval Calculator
Find out when your next oil change is due based on mileage, driving style, and oil type.
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Why use Nivesly calculators?
Every calculator runs entirely in your browser — results are instant and nothing is stored. Whether you're comparing mortgage rates, tracking your BMI, or calculating days between dates, each tool gives you a clear, accurate answer in seconds.
- No sign-up or account required
- Instant calculations in your browser
- Full amortization schedules
- Science-based health formulas
- Retirement and investment projections
- Inflation-adjusted results