Free Online Calculators
Finance, business, math, real estate, and everyday calculators — tools that run in your browser with no sign-ups.
Math & Percentage
Percentage Calculator
Calculate percentages, percentage change, increase, and decrease. Six calculators in one.
Use tool →Percentage Difference
Find the percentage difference between two values. Useful for comparing data and benchmarks.
Use tool →Percent Error
Calculate percent error between experimental and theoretical values for lab reports and analysis.
Use tool →Scientific Calculator
Full-featured scientific calculator with trig, logarithms, exponents, factorial, and keyboard support.
Use tool →Money & Shopping
Tip Calculator
Calculate tips and split bills between any number of people. Preset and custom tip percentages.
Use tool →Discount Calculator
Find the final price after any discount. Add sales tax. See exactly how much you save.
Use tool →Sales Tax Calculator
Calculate sales tax amount and total price. Enter any tax rate to see the full breakdown.
Use tool →Business
Profit Margin Calculator
Calculate gross, operating, and net profit margins from cost and revenue figures.
Use tool →Break-Even Calculator
Estimate break-even units, required revenue, and margin of safety from your cost structure.
Use tool →Markup vs Margin
Convert between markup and margin percentages. See the difference and avoid pricing mistakes.
Use tool →ROI Calculator
Calculate return on investment from initial cost and final value. See annualized returns.
Use tool →Conversion Rate Calculator
Calculate conversion rate from visitors and conversions. Compare against industry benchmarks.
Use tool →Hourly Rate Calculator
Calculate your ideal hourly rate from annual income goals, expenses, and billable hours.
Use tool →Pricing Calculator
Set profitable prices using direct costs, overhead allocation, fees, and target margin assumptions.
Use tool →Invoice Generator
Create itemized invoices with tax and discount totals, then print or save as PDF.
Use tool →Business Loan Calculator
Estimate business loan payment, total interest, fee impact, and net funding received.
Use tool →Customer Lifetime Value
Calculate CLV from purchase value, frequency, and lifespan. See CLV:CAC ratio and net value.
Use tool →Meeting Cost Calculator
Calculate the true cost of meetings based on attendee salaries and duration. See annual impact.
Use tool →Time Tracking Calculator
Log time entries, track hours worked, and calculate billable amounts with your hourly rate.
Use tool →Project Cost Estimator
Add line items with quantity and unit cost, set contingency, and get a full project estimate.
Use tool →Startup Cost Calculator
Estimate total startup costs across legal, equipment, marketing, operations, and working capital.
Use tool →Quote & Estimate Generator
Create professional quotes and estimates with line items, scope of work, terms, and automatic totals.
Use tool →Employee Cost Calculator
Calculate the true cost of hiring beyond salary — taxes, benefits, equipment, and overhead included.
Use tool →Cash Flow Forecast
Project monthly cash flow with income sources, expenses, and one-time items over 3–12 months.
Use tool →Affiliate Earnings Calculator
Estimate affiliate marketing income from traffic, click-through rate, conversion rate, and commission.
Use tool →Loans & Savings
Loan Calculator
Calculate monthly payments, total interest, and view a full amortization schedule.
Use tool →Auto Loan Calculator
Calculate monthly car payments with trade-in, down payment, and sales tax included.
Use tool →Credit Card Payoff
See how long to pay off credit card debt and how much interest you'll pay at different payment amounts.
Use tool →Debt Payoff Calculator
Compare snowball and avalanche strategies, see your debt-free date, and estimate interest savings.
Use tool →Budget Calculator
Track monthly cash flow and compare your spending mix against the 50/30/20 rule.
Use tool →Down Payment Calculator
Calculate how much to save for a home down payment and how long it will take.
Use tool →Savings Goal Calculator
Calculate monthly savings needed to reach your financial goal by a target date.
Use tool →Retirement Calculator
Project nest egg growth, target savings needs, and retirement income sustainability.
Use tool →Compound Interest Calculator
Calculate future value with compound interest, monthly contributions, and multiple compounding frequencies.
Use tool →Early Repayment Calculator
See how much time and interest you save by making extra payments on any loan.
Use tool →Salary Calculator
Convert between hourly, weekly, bi-weekly, monthly, and annual pay. Adjust hours and weeks.
Use tool →Paycheck Calculator
Calculate take-home pay after federal and state taxes, FICA, and deductions.
Use tool →Home & Real Estate
Mortgage Payment Calculator
Estimate full monthly housing payment including taxes, insurance, HOA, PMI, and closing costs.
Use tool →Affordability Calculator
Estimate max home price using income, debt, DTI limits, and total housing cost assumptions.
Use tool →Refinance Calculator
Compare your current loan against refinance terms with break-even and long-term cost impact.
Use tool →Rent vs Buy Calculator
Compare long-term net worth outcomes using appreciation, rent growth, and investment return assumptions.
Use tool →Property Tax Calculator
Estimate annual and monthly property tax based on home value, exemptions, and local rate.
Use tool →Net Proceeds Calculator
Estimate real estate seller proceeds after commissions, fees, taxes, and mortgage payoff.
Use tool →Commission Calculator
Calculate sales commission with flat or tiered rates. See splits, effective rate, and net to seller.
Use tool →Closing Cost Estimator
Estimate buyer or seller closing costs with itemized fees, taxes, and cash-needed-at-closing totals.
Use tool →Rental Property ROI
Analyze rental property investments with cash flow, cap rate, cash-on-cash return, and NOI calculations.
Use tool →Date & Time
Unit Conversion
Weight Converter
Convert between pounds, ounces, grams, kilograms, stone, and tons instantly with formulas and reference output.
Use tool →Length Converter
Convert between inches, centimeters, millimeters, meters, kilometers, feet, yards, and miles.
Use tool →Fahrenheit to Celsius
Convert between °F and °C with step-by-step formulas. Includes Kelvin and common temperature labels.
Use tool →Education
Health & Fitness
BMI Calculator
Calculate body mass index with visual scale and body fat estimation.
Use tool →Calorie Calculator
Calculate BMR, TDEE, and daily calorie targets for your goals.
Use tool →Macro Calculator
Split daily calories into protein, carbs, and fat with diet presets.
Use tool →Protein Calculator
Calculate daily protein needs based on weight, activity, and goals.
Use tool →One Rep Max Calculator
Estimate your one-rep max with Epley and Brzycki formulas.
Use tool →Every Calculator You Need, All in One Place
SmarterSources brings together free online calculators covering finance, business, math, real estate, and everyday life. Instead of hunting across dozens of websites cluttered with ads and pop-ups, you get clean, fast tools that run entirely in your browser. No accounts, no installs, no data collection — just open a calculator and get your answer.
Finance & Personal Money
From splitting a dinner bill with the tip calculator to planning your retirement, the finance tools help you make confident money decisions. Calculate loan payments and view full amortization schedules, figure out how long it will take to pay off credit card debt, build a monthly budget using the 50/30/20 rule, or see exactly how much you need to save each month to hit a financial goal. Every result is instant and every formula is transparent.
Business & Pricing
Running a business means making pricing and profitability decisions every day. The business calculators help you set profitable prices with full cost accounting, calculate ROI on investments, find your break-even point, generate professional invoices, and understand the critical difference between markup and margin. Whether you are a freelancer setting hourly rates or a founder modeling loan scenarios, these tools give you clarity without spreadsheet complexity.
Real Estate & Home Buying
Buying, selling, or refinancing a home involves dozens of variables. The real estate calculators break it all down: estimate your full monthly mortgage payment including taxes and insurance, find out how much house you can afford based on your income and debts, compare renting vs. buying over time, calculate seller net proceeds after all fees, and determine whether refinancing actually saves you money after closing costs.
Math & Percentages
The math calculators handle the percentage problems that come up in school, work, and everyday life. Calculate percentage change, find the difference between two values, or determine percent error for lab reports. Simple inputs, clear results, and the formulas shown so you understand the math behind every answer.
Frequently Asked Questions
Are these calculators accurate?
Yes. Every calculator uses standard, well-documented financial and mathematical formulas. Results match what you would get from a spreadsheet or scientific calculator. For financial calculators, we use the same amortization and compound interest formulas used by banks and lenders.
Can I see the formulas behind each calculator?
Many of the calculators display the formula or methodology used alongside the results. Since all tools run client-side in your browser, you can also inspect the source code directly to verify any calculation logic.
Do I need to create an account or sign up?
No. Every calculator is completely free and requires no account, email address, or sign-up of any kind. Just open the page and start calculating.
Is my financial data stored or shared?
No. All calculations happen locally in your browser using JavaScript. Nothing you enter is sent to a server, stored in a database, or shared with anyone. Your numbers stay on your device.
Can I use these calculators on my phone?
Yes. Every calculator is fully responsive and works on phones, tablets, and desktops. The interfaces are designed for touch input so you can calculate on the go without downloading an app.