Calculators
Everyday calculators for dates, health, and numbers. 26 tools
Arithmetic that is easy to get subtly wrong: percentages in both directions, what a loan actually costs once interest compounds, an age in years and days, the same moment in two time zones, the right split on a bill.
Each shows the working rather than only the answer, which matters when the result is going into something you have to defend — a quote, an invoice, or a deadline.
All 26 calculators
Paint Coverage Calculator
Estimate paint and whole cans from area, openings, coats and your product's coverage.
Tile Calculator
Estimate tile quantities and full boxes with explicit waste and metric or imperial units.
Percentage Calculator
Calculate percentages, reverse changes, compound changes and percentage points with a CSV breakdown.
Age & Birthday Calculator
Calculate calendar age, completed months and birthday milestones with explicit leap-day rules.
Unit Converter
Convert length, weight and temperature — mm to inches, kg to pounds, Celsius to Fahrenheit.
Electrical Load Calculator
Build an appliance schedule; estimate demand, kW, kVA, phase current, tariff and load headroom.
Land Plot Area Calculator
Area of a four-sided plot with unequal sides, in bigha, katha, guntha, acre or hectare.
NPK Calculator
Audit fertilizer blends and targets, split NPK ratios, and convert P2O5 to P or K2O to K.
DAP Calculator
Calculate DAP and urea bags, exact application kg, leftovers, nitrogen credit and field coverage.
Fertilizer Calculator
Find a least-cost whole-bag mix for an N-P-K target using your products, prices, stock and dealer limits.
Loan / EMI Calculator
Calculate monthly payments, total interest, and payoff schedule.
Tip Calculator
Calculate a tip, exclude included tax and split every cent fairly with clear rounding.
Random Number Generator
Generate exact random integers with exclusions, no repeats and local TXT or JSON downloads.
LCM & GCF Calculator
Find exact LCM and GCF/HCF/GCD answers with prime-factor and Euclidean steps you can verify.
Volume Calculator
Calculate mixed-unit shapes and partly filled tanks, with diameter input and a CSV calculation.
Grade Calculator
Work out your weighted grade and the letter it lands on, plus the score you need on the work still ahead.
Date Calculator
Add or count dates with custom weekends, excluded dates, endpoint rules and a CSV breakdown.
Printable Calendar
A calendar for any year or one month, weeks starting Monday or Sunday, ready to print or save as a PDF.
Dice Roller
Roll tabletop dice with keep-highest or lowest rules, modifiers, visible rolls and history export.
Compound Interest Calculator
Model compound growth with monthly deposits, clear timing, inflation and a downloadable schedule.
Aspect Ratio Calculator
Read image dimensions, resize proportionally, and calculate fit, crop or anamorphic output.
Time Zone Converter
Convert a time between cities, then compare your own list of them side by side at that same moment.
Pomodoro Timer
Run custom focus and break cycles with elapsed-time tracking, pause controls and a CSV session log.
Plaster Calculator
Calculate cement bags, sand in cubic feet or brass, and plaster coverage after doors and windows.
BMI Calculator
Calculate body mass index in metric or imperial units.
Calorie Calculator
Estimate the calories you burn a day, and what to eat to lose, gain or maintain.
What to know before you pick one
A calculator is only as good as its assumptions
Two loan calculators disagreeing usually means they assume different things, not that one is broken: whether interest compounds monthly or daily, whether a payment lands at the start or end of the period, how a part-month is handled. Where a calculation on this page depends on an assumption, the page says which one it makes. Before relying on a figure for anything that matters, check that its assumption matches your actual agreement.
What an EMI figure does and does not tell you
A monthly instalment is the smallest useful number and the least informative one. The figures that change decisions are the total interest paid over the full term, and how that total moves when the term changes: a longer term lowers the monthly figure and raises the total, sometimes substantially. Comparing two offers on the monthly payment alone is how people end up paying more for the option that felt cheaper.
Percentages are where most everyday errors happen
A rise of 20% followed by a fall of 20% does not return you to where you started, because the second percentage applies to a larger number. A discount applied before tax gives a different total from the same discount applied after. These are not edge cases — they are the ordinary arithmetic of prices and salaries, and they account for most of the mistakes people make by hand.
Dates and times carry hidden rules
Working out the gap between two dates has to account for leap years, months of unequal length, and whether both endpoints count. Add time zones and daylight saving and the same instant can be two different calendar days. This is why an age or duration worked out in your head often disagrees by a day with one worked out properly.
Nothing you enter is transmitted
Every calculator here runs in the browser, so the figures stay on your device. That is deliberate for this category in particular: loan amounts, salaries, ages and health measurements are exactly the sort of details that should not be sitting in someone else’s server log because you wanted a quick answer.