Free Online Calculators

Instant calculators for finance, business, health, math, and everyday decisions — no signup, just answers.

Finance

Financial calculations for investments, loans, and monetary planning.

Compound Interest

Growth of money with reinvested interest.

Simple Interest

Interest calculated only on principal.

Loan Payment

Monthly payment for borrowed amount.

Mortgage

Long-term home loan amortization.

ROI

Return relative to investment cost.

Break-Even

Point where revenue equals cost.

Profit Margin

Profit as percentage of revenue.

CAGR

Average annual growth rate.

Inflation

Purchasing power decrease over time.

NPV

Net present value of future cash flows.

IRR

Discount rate where NPV equals zero.

Growth & Change

Calculators for rates of change, growth patterns, and projections.

Percentage Change

Relative increase or decrease.

Exponential Growth

Growth proportional to size.

Linear Growth

Constant rate increase.

Doubling Time

Time required to double.

Rule of 72

Estimate doubling via interest rate.

Logistic Growth

S-curve constrained growth.

Business

Metrics for startups, SaaS, and business operations.

Customer LTV

Total revenue per customer.

CAC

Cost to acquire one customer.

MRR / ARR

Recurring revenue metrics.

Burn Rate

Monthly spending rate.

Runway

Time before funds deplete.

Contribution Margin

Revenue minus variable cost.

Churn Rate

Customer loss percentage.

Statistics & Probability

Statistical measures and probability calculations.

Average value.

Middle value.

Most frequent value.

Spread of values.

Squared dispersion measure.

Probability

Likelihood of outcome.

Expected Value

Weighted average outcome.

Bayes Theorem

Conditional probability update.

Health

Health and fitness related calculations.

BMI

Body mass index estimate.

BMR

Basal metabolic rate.

Calorie Needs (TDEE)

Total daily energy expenditure.

Body Fat %

Estimated fat proportion.

Heart Rate Zone

Target exercise range.

Time

Time-based calculations and duration tools.

Work Hours

Hours between shifts.

Time Value of Money

Present vs future value.

Math

Core mathematical operations and formulas.

Ratio

Relative comparison of values.

Proportion

Equality of two ratios.

Factorial

Product of descending integers.

Permutations

Ordered arrangements.

Combinations

Unordered selections.

GCD / LCM

Divisor and multiple calculations.

Logarithm

Inverse exponent function.

Quadratic Formula

Solve second-degree equation.

Decision & Optimization

Tools for analysis, ranking, and decision-making.

Opportunity Cost

Value of next best option.

Risk/Reward

Return relative to risk.

Engineering & Physics

Physical laws and engineering formulas.

Ohm's Law

Voltage-current-resistance relation.

Force

Mass times acceleration.

Kinetic Energy

Energy of motion.

Density

Mass per volume.

Pressure

Force per area.