ToolsGuru

Calculators

Free online calculators for finance, health, dates, and everyday math.

10 tools available

Percentage Calculator

Popular

Calculate percentages, percentage change, and percentage of a number with clear step-by-step results.

Updated today

BMI Calculator

Calculate your Body Mass Index using metric or imperial units with healthy range guidance.

Updated today

Age Calculator

Calculate exact age in years, months, days, hours, and minutes from any date of birth.

Updated today

Loan Calculator

Calculate monthly loan payments, total interest, and amortization for mortgages, auto, and personal loans.

Updated today

Compound Interest Calculator

See how investments grow with compound interest. Adjustable contribution, rate, and compounding frequency.

Updated today

Tip Calculator

Calculate tips and split bills between people instantly, with custom tip percentages.

Updated today

Discount Calculator

Calculate sale prices, discount amounts, and percentage savings for shopping and pricing.

Updated today

Date Difference Calculator

Calculate days, weeks, months, and years between two dates. Includes business-day counting.

Updated today

Random Number Generator

Generate random numbers in any range, with options for uniqueness, quantity, and sorting.

Updated today

Fuel Cost Calculator

Estimate trip fuel costs from distance, fuel efficiency, and price per litre or gallon.

Updated today

About our calculators

Everyday calculations deserve better than a bare number pad: you want to see the working, adjust the inputs, and trust the result. ToolsGuru's calculators are purpose-built for the questions people actually ask — what's the monthly payment on this loan, what will this investment grow to, how old exactly, what's a fair tip, and what discount am I really getting.

The collection covers money (loan payments with amortization, compound interest with contribution schedules, tips with bill splitting, discounts, fuel costs), health (BMI with healthy-range guidance), time (exact age down to the day, date differences with business-day counting), and numbers (percentage calculations in three modes, random number generation).

Each calculator shows its reasoning, not just an answer — the percentage calculator displays the formula it used, the loan calculator breaks payments into principal and interest, and the compound interest tool charts growth year by year. All calculations run instantly in your browser with nothing recorded or transmitted.

Why choose ToolsGuru

Shows the working

See formulas and breakdowns, not just a number — useful for checking and learning.

Real-world modes

Business-day counting, bill splitting, MPG or L/100km — built for actual use cases.

Adjust and compare

Change any input and watch the result update instantly. Great for what-if planning.

Completely private

Financial and health inputs are never transmitted or stored.

Frequently asked questions

How is the loan payment calculated?

Using the standard amortization formula: M = P × r(1+r)ⁿ / ((1+r)ⁿ−1), where P is the principal, r the monthly interest rate, and n the number of payments. The calculator also totals interest over the life of the loan and handles 0% financing correctly.

How accurate is the BMI calculator?

It applies the WHO formula (weight ÷ height²) exactly, in metric or imperial units, and maps the result to the standard categories. BMI is a screening indicator, not a diagnosis — athletes and older adults should interpret it with professional advice.

What's the difference between simple and compound interest?

Simple interest is earned only on the principal; compound interest is earned on the principal plus previously earned interest, so growth accelerates over time. The compound interest calculator lets you set the compounding frequency and monthly contributions to model realistic saving.

Are the random numbers truly random?

They're generated with your browser's cryptographically secure random source where uniqueness matters, which is more than sufficient for draws, sampling, and games. For regulated lotteries or cryptographic keys, use certified dedicated systems.