Why You Need More Than One Calculator
Your phone's built-in calculator handles arithmetic. For anything more — mortgage payments, compound interest, BMI, unit conversions, percentage changes, tip splits — you need specialised calculators that understand the inputs and show workings. allio.tools provides 27 free calculators covering finance, health, math, and everyday calculations, all in one place, all free and browser-based.
Scientific Calculator — Beyond Basic Arithmetic
The Scientific Calculator at allio.tools/tools/calculators/scientific-calculator/ includes trigonometric functions (sin, cos, tan and inverses), logarithms (log base 10 and natural log), exponentiation, square roots, factorials, and parenthesis grouping for complex expressions. It follows standard operator precedence (PEMDAS/BODMAS), so 2+3×4 correctly returns 14, not 20. There is also a history panel showing your last 10 calculations, useful when building up multi-step solutions.
Mortgage Calculator — The Number Every Buyer Needs
The Mortgage Calculator at allio.tools/tools/calculators/mortgage-calculator/ computes monthly payment, total interest paid, and a full amortization schedule. Enter principal, annual interest rate, and term in years. The amortization table is the most valuable output: it shows, year by year, how much of each payment goes to interest versus principal. In the early years of a 30-year mortgage, over 80% of each payment is interest — a fact that motivates extra payments and reveals the true cost of borrowing.
Compound Interest Calculator — The Most Important Financial Tool
The Compound Interest Calculator at allio.tools/tools/calculators/compound-interest-calculator/ shows how money grows over time with regular contributions, a fixed annual rate, and a chosen compounding frequency. The results are expressed as a total value, total contributions, and total interest earned — breaking down exactly how much of your future wealth is the money you put in versus the interest it generated. Running this calculation for 10, 20, and 30 years makes an abstract concept visceral: starting a savings habit 10 years earlier can double the result.
Percentage Calculator — Three Formulas in One
Percentage calculations come in three forms that people confuse: 'What is X% of Y?', 'X is what percent of Y?', and 'What is the percentage change from X to Y?'. The Percentage Calculator at allio.tools/tools/calculators/percentage-calculator/ handles all three with clearly labelled fields, so you pick the question you are asking and enter the numbers you know. Useful for discounts, markups, exam scores, and financial changes.
BMI and Health Calculators
The health calculators at allio.tools/tools/health/ include BMI (Body Mass Index with WHO classification), TDEE (Total Daily Energy Expenditure — how many calories you burn daily based on activity level), daily water intake recommendation, sleep cycle calculator (showing ideal bedtimes based on your wake time), and ideal weight ranges based on height and frame. These use standard medical formulas and are provided for informational reference, not medical advice.
Unit Converter — Length, Weight, Temperature, Volume
The Unit Converter at allio.tools/tools/calculators/unit-converter/ handles the four most common conversion categories: length (mm, cm, m, km, inch, foot, yard, mile), weight/mass (mg, g, kg, tonne, oz, lb), temperature (Celsius, Fahrenheit, Kelvin), and volume (ml, L, fl oz, cup, pint, gallon). Conversions update as you type without pressing a button, and all values for a category display simultaneously so you can scan across units quickly.
Tip Calculator — Split Any Bill Instantly
The Tip Calculator at allio.tools/tools/calculators/tip-calculator/ takes a bill total, tip percentage, and number of people splitting the bill, and shows the tip amount, total bill, and per-person amount. It handles non-round splits correctly — if four people split a $67.40 bill with a 20% tip, it shows $20.22 per person, not a rounded approximation.