💯 Calculators

Three live calculators for every percent problem.

Exact age plus totals and next birthday.

Calculate BMI instantly — metric or imperial.

Future value with compound interest and deposits.

Birth date to all three Korean age systems.

Estimate monthly net pay after Korean taxes.

Weighted GPA from grades and credits, 4.0 or 4.5.

Monthly payment, interest total, amortization schedule.

Trig, log, roots, factorial — safe offline evaluator.

Final price and savings for any sale or stacked deal.

Bedtime or wake-up times based on 90-min sleep cycles.

Days, weeks, months, years between two dates.

Split bill and tip by party size instantly.

Compare price per unit across products.

Find the selling price for a target profit margin.

Find the units needed to break even.

See how many months of cash runway you have left.

Estimate customer LTV and your LTV:CAC ratio.

Compute Net Promoter Score from 0–10 responses.

Calculate customer acquisition cost and payback months.

Odds over many tries: at least once, exactly k, expected count.