80+ Free Calculators — No Registration Required

Every Calculator
You'll Ever Need

From mortgage payments and BMI to binary math and DeFi analysis — JustCalculators.app is your free, instant, all-in-one calculation resource.

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💰 Financial Calculators

401(k) Calculator

Project 401k balance with employer match and tax-deferred growth

Amortization Calculator

Complete payment-by-payment loan amortization schedule

Annuity Calculator

Future value of regular deposits with compound growth

Auto Loan + Amortization

Car loan with complete month-by-month payment schedule

Auto Loan Calculator

Car payments with trade-in value and sales tax

Business Loan Calculator

Commercial loan payments and cash flow impact

Certificate of deposit value and interest at maturity

Compound Interest Calculator

Investment growth with regular contributions

Credit Card Interest Calculator

True cost of carrying a monthly credit card balance

Credit Card Payoff Calculator

How long and how much to pay off your balance

Debt Consolidation Calculator

Compare consolidating debts vs. paying separately

Debt-to-Income (DTI) Ratio

DTI ratio for mortgage and loan qualification

Depreciation Calculator

Straight-line and declining balance depreciation

Estate Tax Calculator

Federal estate tax based on 2024 exemptions

Finance (TVM) Calculator

Solve any time-value-of-money variable

Health Savings Account growth and triple tax advantage

Income Tax Calculator

Estimate federal tax, effective rate, and marginal bracket

Inflation Calculator

How inflation erodes purchasing power over time

Interest Calculator

Simple and compound interest for any loan or savings

Interest Rate Calculator

Find the implied interest rate from loan variables

Investment Calculator

Project portfolio growth with contributions and returns

Lease Calculator

Monthly lease payments for cars and equipment

Loan Calculator

Monthly payment and total interest for any installment loan

Margin Calculator

Profit margin and markup for pricing and analysis

Mortgage Calculator

Monthly PITI with amortization, PMI, taxes & insurance

Mortgage Payoff Calculator

Save years and interest with extra mortgage payments

Paycheck Calculator

Estimate take-home pay after taxes and deductions

Personal Loan Calculator

Monthly payment for any unsecured personal loan

Present Value Calculator

Discounted cash flow and time value of money

Return on investment for any business or investment

Rental Property Calculator

Cash flow, cap rate, NOI, and real estate ROI

Retirement Calculator

Are you on track? Find your retirement savings gap

Retirement Planner

Comprehensive retirement income gap analysis

Sales Tax Calculator

Calculate tax amount and total price for any rate

Savings Calculator

Project savings balance with deposits and interest

Simple Interest Calculator

Quick I=PRT interest calculations

Student Loan Calculator

Payments and payoff timeline for federal/private loans

Add or remove Value Added Tax for any rate

Wage / Salary Calculator

Convert hourly, weekly, monthly, and annual pay rates

❤️ Health & Fitness Calculators

BAC / Blood Alcohol Calculator

Estimate BAC by drinks, weight, sex, and time elapsed

Body Mass Index — imperial and metric units with health range

Calories burned at complete rest (Mifflin-St Jeor)

Body Fat Calculator

Body fat % using US Navy circumference method

Body Surface Area (BSA)

BSA for clinical and pharmaceutical dosing

Calorie Calculator

Daily calorie needs (Mifflin-St Jeor equation)

Conception Calculator

Estimate your conception date from due date or LMP

Due Date Calculator

Estimated due date from LMP or conception date

Ideal Weight Calculator

Four evidence-based IBW formulas compared

Lean Body Mass Calculator

Fat-free mass for accurate nutrition targeting

Macro Calculator

Protein, carbs, and fat targets for your goals

Ovulation Calculator

Fertile window and ovulation day from cycle length

Pace Calculator

Running pace, finish time, or distance from any two values

Pregnancy Weight Gain

IOM-recommended weight gain by pre-pregnancy BMI

TDEE Calculator

Total daily energy expenditure with activity level

Target Heart Rate

Max HR and fat-burn/cardio/threshold training zones

Waist-to-Hip Ratio

Cardiovascular risk from body shape measurements

Water Intake Calculator

Daily hydration needs by weight and activity level

➗ Math Calculators

Basic Calculator

Clean four-function calculator with memory, √, % and history

Algebra Calculator

Solve linear and quadratic equations, simplify expressions

Average Calculator

Mean, weighted average, geometric and harmonic mean

Binary Calculator

Binary arithmetic and conversion between number bases

Circle Calculator

Area, circumference, diameter from any single measurement

Fraction Calculator

Add, subtract, multiply, divide with auto-simplification

Graphing Calculator

Plot functions and visualize equations interactively

Percentage Calculator

X% of Y, what % X is of Y, and % change

Quadratic Formula

Solve ax²+bx+c=0 including complex roots

Rounding Calculator

Round to decimal places or significant figures

Scientific Notation

Convert to/from scientific notation and perform operations

Standard Deviation

Population and sample standard deviation with full analysis

Statistics Calculator

Mean, median, mode, range, variance from any dataset

Triangle Calculator

Area, angles, sides, perimeter from any known values

🔧 Utility Calculators

Exact age in years, months, days plus birthday countdown

Base64 Encoder/Decoder

Encode text to Base64 or decode Base64 strings

Binary to Text Converter

Convert between binary code and readable ASCII text

Engagement Rate Calculator

Social media engagement rate vs. industry benchmarks

Semester and cumulative GPA from letter grades

Password Generator

Strong, secure random passwords with custom settings

RGB to HEX Converter

Convert color codes for web and CSS design

Random Number Generator

Random integers in any range

Sales Tax Calculator

Calculate tax amount and total for any rate

TV Viewing Distance

Ideal TV size and viewing distance for your room

Tip amount, total, and per-person split

Length, weight, volume, temperature, speed and more

₿ Crypto / DeFi Calculators

Impermanent Loss Calculator

DeFi AMM liquidity pool IL from price changes

Why JustCalculators.app?

⚡

Instant Results

All calculations run in your browser — no server delays, no waiting, results appear immediately.

🎯

Accurate Formulas

Every calculator uses clinically- and financially-verified formulas with cited sources.

🔒

Private by Design

Your inputs never leave your device. Zero data collection on what you calculate.

📱

Works on Any Device

Fully responsive — desktop, tablet, and mobile. Any browser, any screen size.

Free Online Calculators for Every Need

JustCalculators.app provides more than 80 free online calculators across five major categories: financial, health & fitness, math, utility, and crypto/DeFi. Every tool delivers instant, accurate results directly in your browser — no registration, no subscription, no downloads required.

Our financial calculators cover the full spectrum of personal and business finance — from calculating a monthly mortgage payment with full amortization to projecting your 401(k) balance at retirement, estimating federal income tax liability, and analyzing the ROI on a rental property investment.

Our health & fitness calculators use scientifically-validated formulas: the Mifflin-St Jeor equation for calorie and TDEE calculations, CDC guidelines for BMI classification, and the US Navy circumference method for body fat estimation.

Whether you're a student solving quadratic equations, a homebuyer comparing 15-year vs. 30-year mortgages, an investor analyzing a rental property's cap rate, or someone tracking their daily nutrition macros — JustCalculators.app has the right tool, available 24/7, completely free.