Free online calculators for everyday maths, finance, health, and programming. The Scientific Calculator handles trigonometry, logarithms, exponents, and standard arithmetic. The Loan Calculator computes monthly payments, total interest, and amortisation schedules for mortgages, car loans, and personal loans. The BMI Calculator and Age Calculator cover health metrics. The Tip and Percentage Calculators handle restaurant bills and discount calculations. The Salary Calculator converts between hourly, daily, weekly, monthly, and annual rates with tax estimation. The Programmer Calculator works in binary, octal, decimal, and hexadecimal with bitwise operation support.

When to use Calculators

1Financial planning: use the Loan Calculator to model monthly payments and total cost for different loan amounts, interest rates, and term lengths before signing a mortgage or car loan.
2Freelance and job negotiations: use the Salary Calculator to convert a day rate to an annual equivalent, or to see the net take-home from a gross salary offer.
3Health tracking: calculate BMI to track changes over time, or use the Age Calculator to determine exact age in years, months, and days for medical forms.
4Restaurant bills: split the Tip Calculator among multiple people with different tip percentages - or use the Percentage Calculator for discount and sale price calculations.
5Low-level programming: use the Programmer Calculator for binary/hex arithmetic and bitwise operations (AND, OR, XOR, shifts) when working with flags, masks, and memory addresses.

Frequently Asked Questions

How is BMI calculated?+

BMI (Body Mass Index) = weight in kilograms ÷ (height in metres)². For example, a person who is 70kg and 1.75m tall has a BMI of 70 ÷ (1.75²) = 22.9. The BMI Calculator accepts both metric and imperial inputs. BMI is a screening tool, not a diagnostic measure - it does not account for muscle mass, bone density, age, or sex.

How do I calculate monthly loan repayments?+

Monthly payment = P × (r(1+r)^n) ÷ ((1+r)^n - 1), where P is the principal, r is the monthly interest rate (annual rate ÷ 12), and n is the number of monthly payments. The Loan Calculator does this instantly and also shows the total amount repaid and total interest paid over the full loan term.

How do I convert a contractor day rate to an equivalent salary?+

Multiply the day rate by the number of working days per year (typically 220–230 after holidays and sick days). A £400/day contractor rate equals approximately £88,000–£92,000 gross per year. However, contractors also pay self-employment taxes and receive no employer benefits, so a like-for-like comparison to a PAYE salary requires reducing by 30–40%.

What does left shift (<<) do in the Programmer Calculator?+

Left shift moves all bits of a number left by N positions and fills the vacated right bits with zeros. This is equivalent to multiplying by 2^N. For example, 5 << 2 = 20 (5 × 4). Right shift (>>) divides by powers of 2. Bitwise shifts are faster than multiplication on some processors and are commonly used in embedded systems, graphics, and cryptography.

About Calculators

When to use Calculators

1Financial planning: use the Loan Calculator to model monthly payments and total cost for different loan amounts, interest rates, and term lengths before signing a mortgage or car loan.

2Freelance and job negotiations: use the Salary Calculator to convert a day rate to an annual equivalent, or to see the net take-home from a gross salary offer.

3Health tracking: calculate BMI to track changes over time, or use the Age Calculator to determine exact age in years, months, and days for medical forms.

4Restaurant bills: split the Tip Calculator among multiple people with different tip percentages - or use the Percentage Calculator for discount and sale price calculations.

5Low-level programming: use the Programmer Calculator for binary/hex arithmetic and bitwise operations (AND, OR, XOR, shifts) when working with flags, masks, and memory addresses.

Frequently Asked Questions

How is BMI calculated?+

How do I calculate monthly loan repayments?+

How do I convert a contractor day rate to an equivalent salary?+

What does left shift (<<) do in the Programmer Calculator?+