---
title: "Online Calculators for Math and Everyday Numbers"
description: "Calculate percentages, fractions, averages, loan payments and other everyday numbers. Browser calculators with visible inputs and explained assumptions."
url: https://candoya.com/tools/calc/
locale: en
type: tool-category
---

# Calculators for everyday decisions

Start with the question you are trying to answer. Percentage Calculator finds a share of a number, while Percentage Change compares an old value with a new one. Fraction tools preserve a ratio in a form that decimal rounding can obscure. Statistics calculators summarize a dataset, and finance tools model payments, interest and other scenarios. The calculation runs in your browser and you can change an input to see how the answer responds.

The same numbers can answer different questions. A price rising from 80 to 100 is a 25 percent increase; falling from 100 to 80 is a 20 percent decrease. In a dataset, a population standard deviation and a sample standard deviation use different denominators. Check the labels and formula explanation instead of assuming that two calculators with similar names should agree.

For estimates involving money or health, assumptions matter more than extra decimal places. Loan models may exclude fees, taxes or insurance; an interest rate is not always an APR. Health estimates describe a formula, not an individual diagnosis. Use the result to understand a scenario, retain the inputs, and compare it with the terms or measurements that apply to your situation before making a consequential decision.

## Calculators tools

- [Aspect Ratio Calculator](https://candoya.com/tools/aspect-ratio-calculator/): Aspect ratio calculator for images, video and layouts. Reduce width:height, get CSS aspect-ratio, and calculate matching resize dimensions.
- [Big Number Calculator](https://candoya.com/tools/big-number-calculator/): Free big number calculator for exact arbitrary-precision math. Add, multiply, divide and raise huge numbers to powers with no rounding, right in your browser.
- [Correlation Coefficient Calculator](https://candoya.com/tools/correlation-coefficient/): Free correlation coefficient calculator: paste paired X and Y data and get Pearson's r, r squared, Spearman's rank, covariance and the regression line instantly. Runs in your browser.
- [Decimal to Fraction Converter](https://candoya.com/tools/decimal-to-fraction/): Convert decimals to fractions in lowest terms, including negative and repeating decimals. See exact steps and mixed numbers instantly.
- [Fraction Calculator](https://candoya.com/tools/fraction-calculator/): Free online fraction calculator to add, subtract, multiply and divide fractions and mixed numbers. Get the answer in lowest terms instantly, in your browser.
- [Fraction to Decimal Converter](https://candoya.com/tools/fraction-to-decimal/): Convert fractions to decimals online with repeating digits shown in parentheses. Exact BigInt long division, no sign-up, no upload.
- [GCD and LCM Calculator](https://candoya.com/tools/gcd-lcm-calculator/): GCD and LCM calculator for 2 to 20 integers. Get exact answers, normalized values and Euclidean algorithm steps instantly in your browser.
- [Integral Calculator](https://candoya.com/tools/integral-calculator/): Free integral calculator: enter a function and lower and upper limits to evaluate the definite integral instantly. No sign-up, no download - runs in your browser.
- [Matrix Calculator](https://candoya.com/tools/matrix-calculator/): Use this matrix calculator to add, subtract, multiply, transpose, invert, find determinants, and calculate RREF. Free, private, and instant.
- [Mean, Median & Mode Calculator](https://candoya.com/tools/mean-average-calculator/): Free mean median mode calculator: paste a list of numbers and get the mean (average), median, mode, range, sum, count and standard deviation instantly. Runs in your browser.
- [Median & Mode Calculator](https://candoya.com/tools/median-mode-calculator/): Use this median calculator to find the middle value, mode, sorted positions, and frequencies for any number set. Free and private in your browser.
- [Perimeter Calculator](https://candoya.com/tools/perimeter-calculator/): Free perimeter calculator for a rectangle, square, triangle, circle, polygon and more. Pick a shape, enter the dimensions, and get the perimeter with the formula - instantly in your browser.
- [Percentage Change Calculator](https://candoya.com/tools/percentage-change/): Free percentage change calculator: enter an old value and a new value to get the percent increase or decrease instantly, with the worked formula. Runs in your browser.
- [Percentage Calculator](https://candoya.com/tools/percentage-calculator/): Free percentage calculator: find X% of a number, what percent one number is of another, and percent increase or decrease - instantly in your browser.
- [Prime Factorization Calculator](https://candoya.com/tools/prime-factorization/): Use this prime factorization calculator to break integers up to 1 trillion into prime powers, see every division step, and copy the exact result.
- [Quadratic Equation Solver](https://candoya.com/tools/quadratic-equation-solver/): Solve quadratic equations online with real or complex roots, the discriminant, vertex, and clear quadratic formula steps. Free and private.
- [Proportion Solver](https://candoya.com/tools/proportion-solver/): Proportion calculator to solve any missing value in a/b = c/d with exact fractions, decimals, cross multiplication steps, and ratio checks.
- [Ratio Calculator](https://candoya.com/tools/ratio-calculator/): Ratio calculator to simplify two-part or multi-part ratios, find equivalent ratios, percentages and proportional shares of any total.
- [Roman Numeral Converter](https://candoya.com/tools/roman-numeral-converter/): Free Roman numeral converter: turn numbers into Roman numerals and Roman numerals back into numbers (1-3999), instantly in your browser with the worked breakdown.
- [Standard Deviation Calculator](https://candoya.com/tools/standard-deviation-calculator/): Standard deviation calculator for sample or population data. Paste numbers to get standard deviation, variance, mean, and calculation steps instantly.
- [Truth Table Generator](https://candoya.com/tools/truth-table-generator/): Truth table generator for Boolean expressions with AND, OR, NOT, XOR, implication, and equivalence. See every row, minterm, and result instantly.
- [Variance Calculator](https://candoya.com/tools/variance-calculator/): Variance calculator for sample or population data with formulas, mean, standard deviation, and every squared deviation shown. Free and private.
- [Z-Score Calculator](https://candoya.com/tools/z-score-calculator/): Free z-score calculator: enter a raw value, the mean and standard deviation to get the standard score, its percentile, and the probability - instantly in your browser.
- [Amortization Schedule](https://candoya.com/tools/amortization-schedule/): Build a dated amortization schedule with principal, interest, extra payments, annual summaries and CSV export. Free, private and instant.
- [Auto Loan Calculator](https://candoya.com/tools/auto-loan-calculator/): Auto loan calculator with sales tax, trade-in, payoff, down payment and fees. Estimate your car payment, amount financed and total interest.
- [Break-even Calculator](https://candoya.com/tools/break-even-calculator/): Break-even calculator for units, revenue, contribution margin and profit targets. Test fixed and variable costs instantly in your browser.
- [Cap Table Calculator](https://candoya.com/tools/cap-table-calculator/): Cap table calculator for startup ownership and a priced funding round. See shares, dilution and investor percentages instantly in your browser.
- [Commission Calculator](https://candoya.com/tools/commission-calculator/): Commission calculator for flat or tiered sales rates, optional base pay and clear payout breakdowns. Compare progressive and retroactive plans instantly.
- [Compound Interest Calculator](https://candoya.com/tools/compound-interest/): Free compound interest calculator: project how savings grow from a deposit, rate, compounding frequency and regular contributions - final balance and interest, live in your browser.
- [Credit Card Payoff Calculator](https://candoya.com/tools/credit-card-payoff/): Use this free credit card payoff calculator to estimate your payoff time, monthly payment, total interest and month-by-month balance. No sign-up.
- [Debt Snowball vs Avalanche Calculator](https://candoya.com/tools/debt-snowball-avalanche/): Free debt payoff calculator comparing the snowball and avalanche methods. Enter your debts and extra payment to see which clears them faster and cheaper.
- [Discount Calculator](https://candoya.com/tools/discount-calculator/): Free discount calculator to work out sale price, savings, discount percentage and original price. Instant retail math, no sign-up.
- [Gross Margin Calculator](https://candoya.com/tools/gross-margin-calculator/): Free gross margin calculator for revenue and COGS. See gross profit, margin and markup, or plan target revenue instantly in your browser.
- [Home Affordability Calculator](https://candoya.com/tools/home-affordability/): Free home affordability calculator: estimate how much house you can afford from income, debts, down payment, mortgage rate, taxes, insurance, HOA and PMI.
- [Hourly to Salary Calculator](https://candoya.com/tools/hourly-to-salary/): Hourly to salary calculator for annual, monthly, biweekly, and weekly gross pay. Adjust paid hours and weeks for a realistic estimate.
- [Loan Calculator with Amortization Schedule](https://candoya.com/tools/loan-calculator/): Free loan calculator: enter the amount, interest rate and term to get your monthly payment, total interest, total cost and a full month-by-month amortization schedule - live in your browser.
- [Markup vs Margin](https://candoya.com/tools/markup-vs-margin/): Convert markup to margin or margin to markup instantly. Compare the two profit percentages and see the price from any sample cost.
- [Mortgage Calculator with Taxes, Insurance & PMI](https://candoya.com/tools/mortgage-calculator/): Free mortgage calculator: enter home price, down payment, rate and term to get your full monthly payment - principal, interest, property tax, home insurance and PMI - plus a live amortization schedule.
- [Mortgage Overpayment Calculator](https://candoya.com/tools/mortgage-overpayment/): Mortgage overpayment calculator for recurring and one-off extra payments. Compare interest and time saved with a clear payoff schedule.
- [MRR and ARR Calculator](https://candoya.com/tools/mrr-arr-calculator/): MRR and ARR calculator for SaaS plan mixes. Normalize monthly, quarterly and annual subscriptions into clear recurring revenue totals instantly.
- [NPV Calculator](https://candoya.com/tools/npv-calculator/): NPV calculator with editable cash flows, a discounted period table and worked net present value result. Free, private and no sign-up required.
- [Profit Margin Calculator](https://candoya.com/tools/profit-margin-calculator/): Free profit margin calculator to work out margin, markup, profit and target selling price. Instant pricing math, no sign-up.
- [Rent vs Buy Calculator](https://candoya.com/tools/rent-vs-buy/): Use this free rent vs buy calculator to compare home equity, rent, mortgage costs, maintenance, appreciation and invested savings over time.
- [Retirement Calculator](https://candoya.com/tools/retirement-calculator/): Retirement calculator to project your savings, income target and monthly contribution. Include inflation and expected return with no sign-up.
- [ROI Calculator](https://candoya.com/tools/roi-calculator/): ROI calculator for gain or loss, return percentage, break-even value and optional annualized ROI. Clear formulas, no sign-up and no upload.
- [ROAS Calculator](https://candoya.com/tools/roas-calculator/): ROAS calculator for return on ad spend as a multiple, ratio and percentage, with optional break-even ROAS from gross margin. Free and private.
- [Startup Runway Calculator](https://candoya.com/tools/runway-calculator/): Startup runway calculator for cash, monthly expenses and revenue. See net burn, months remaining, zero-cash date and an 18-month target check.
- [Savings Goal Calculator](https://candoya.com/tools/savings-goal-calculator/): Savings goal calculator to find how much to save each month for a target and deadline. Include current savings and APY, with no sign-up.
- [Invoice Generator](https://candoya.com/tools/invoice-generator/): Free invoice generator for creating printable invoices with line items, tax, discounts, payments and HTML download. Private, no sign-up.
- [Tip Calculator](https://candoya.com/tools/tip-calculator/): Free tip calculator to work out gratuity, tax, total and split bill amounts instantly. Round the total or each share, no sign-up.
- [Unit Price Comparison](https://candoya.com/tools/unit-price-comparison/): Unit price calculator to compare two packages by item, weight, or volume. Convert mixed units instantly and see which option costs less.
- [VAT Calculator](https://candoya.com/tools/vat-calculator/): VAT calculator to add or remove VAT and split any price into net, tax and gross amounts. Use any rate and currency, with no sign-up.
- [Vesting Schedule Calculator](https://candoya.com/tools/vesting-schedule/): Free vesting schedule calculator for RSUs, stock options and equity grants. Set your start date, cliff and term to see exactly what has vested and when.
- [BMI Calculator](https://candoya.com/tools/bmi-calculator/): Free BMI calculator. Enter your height and weight in metric or imperial units to get your Body Mass Index and WHO weight category instantly in your browser.
- [BMR Calculator](https://candoya.com/tools/bmr-calculator/): Free BMR calculator using the Mifflin-St Jeor equation. Estimate resting calories from age, sex, height and weight in metric or US units.
- [Calories Burned by Activity Calculator](https://candoya.com/tools/calories-burned-by-activity/): Free calories burned by activity calculator. Pick an activity, enter weight and minutes, and estimate kcal with the standard MET formula in your browser.
- [Running Pace Calculator](https://candoya.com/tools/running-pace-calculator/): Free running pace calculator for pace per km and mile, speed, and even race splits. Enter distance and time in metric or imperial units.
- [TDEE Calculator](https://candoya.com/tools/tdee-calculator/): Free TDEE calculator for daily calorie needs. Estimate maintenance calories from age, height, weight, sex and activity in metric or US units.

[All tools](https://candoya.com/tools/)

---

*Markdown edition of <https://candoya.com/tools/calc/>, published for AI agents and other automated readers. Index of key pages: <https://candoya.com/llms.txt>.*