CalcKit

Free online calculators.

Fast, accurate calculators for business, finance and everyday life.

Popular calculators

PercentageFind a percentage of any number, from small amounts to large totals.Profit MarginFind your gross profit and the share of revenue you keep.LoanEstimate monthly payments, total interest and borrowing costs.Compound InterestSee how interest and regular contributions grow over time.ROIMeasure your net gain as a percentage of your investment.DiscountFind the sale price and how much you save on a purchase.AgeCalculate age in years, months and days from a date of birth.Freelance RateSet an hourly rate around your income, expenses and billable time.
Browse all 20 calculators

Find your category

BusinessUnderstand margins, pricing, growth and the numbers behind your business.5 toolsFreelancerSet sustainable rates, price projects and plan your billable time.4 toolsFinanceEstimate borrowing costs, savings growth and investment returns.5 toolsEverydayQuick answers for percentages, shopping discounts and splitting a bill.4 toolsDate & TimeFind your age or count the days between two calendar dates.2 tools

Choose a calculator for your next step

Start with the question you need to answer. For a product price, compare profit margin with markup: one measures profit against revenue, the other against cost. For a client quote, estimate billable hours before setting a freelance rate.

For borrowing, the Loan Calculator shows both monthly payments and total interest. For regular deposits, use the Savings Calculator; use Compound Interest to compare compounding frequencies. For a quick comparison or duration, try Percentage Change or Date Difference.

Read the assumptions before using a result

Every calculator includes its formula, a worked example and instructions. Keep units consistent, distinguish total returns from annualized returns, and check whether date counting includes both endpoints. Monetary inputs can use another currency when every amount uses the same unit; displays use US dollars and do not convert exchange rates. Finance tools use simplified, constant-rate models. Read our calculation methods and assumptions for details.

Calculate, compare and share

Enter your values, calculate a result, then change one input to compare scenarios. No account is needed. Calculations run in your browser. Share URL creates a link containing the values you entered, so share only information you are comfortable disclosing. Our privacy page explains shared links and traffic analytics.