Guides
Understand the answer, not only the number.
Plain-language explanations of formulas, assumptions, edge cases, and the choices behind Desmarto tools.
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Featured guides
Work & pay
How to Calculate Hours Worked
Learn how to calculate hours worked accurately, including break deductions, overtime, and overnight shifts.
6 min readRead guide
Finance
How Mortgage Interest Works
Learn how mortgage interest is calculated, how amortization works, and how your monthly payments are structured.
6 min readRead guide
Dates
How to Calculate Age Correctly
Learn how age is calculated precisely: years, months, days. Understand leap year handling and legal age considerations.
6 min readRead guide
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Time
5 published guides
What Is UTC?Learn what UTC is, how it differs from GMT, why it is the world's time standard, and how time zones relate to it.Time Zone Abbreviations ExplainedA complete guide to common time zone abbreviations: EST, PST, CET, GMT, IST, JST, and others explained with UTC offsets.AM vs PM ExplainedLearn the meaning of AM and PM, how the 12-hour clock works, and how to avoid confusion when converting to 24-hour time.Military Time ExplainedLearn how military time (24-hour clock) works, how to read it, and how to convert between 12-hour and 24-hour formats.How to Calculate Time DurationLearn how to calculate time duration between two times, handle overnight spans, and avoid common mistakes.
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Dates
8 published guides
How Many Days Are in a Leap YearLearn the leap year rules: why we add February 29, the divisibility rule, and which century years are exceptions.What Is a Julian DateLearn what Julian dates are, how they differ from calendar dates, and when they are used in astronomy and programming.How to Calculate Age CorrectlyLearn how age is calculated precisely: years, months, days. Understand leap year handling and legal age considerations.How Many Weeks Are in a YearA standard year has 52 weeks plus 1 day. Learn how ISO week numbers work and why some years have 53.How to Calculate Date DifferencesLearn how to calculate the exact difference between two dates, including calendar months, total days, and business days.ISO Week Dates ExplainedUnderstand the ISO week date system: how weeks are numbered, when week 1 starts, and why it matters.How to Calculate Day of YearLearn how the day of year (ordinal date) is calculated, what day number today is, and its uses.Business Days vs Calendar DaysWhen to use each and how they are calculated differently. A practical guide for deadlines, contracts, and project planning.
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Work & pay
12 published guides
How to Calculate Business DaysLearn how to count weekdays between dates and verify public holidays separately when required.How to Calculate Hours WorkedLearn how to calculate hours worked accurately, including break deductions, overtime, and overnight shifts.How Daylight Saving Time WorksLearn how DST works, which countries observe it, when clocks change, and how to avoid scheduling mistakes.Decimal Hours ExplainedLearn how decimal hours work, how to convert minutes to decimal hours, and why payroll systems use decimal time.How Overtime Is CalculatedLearn how overtime is calculated under US FLSA rules, common overtime rates, and how to calculate overtime pay accurately.Work Hours vs Paid HoursUnderstand the difference between hours worked and hours paid, including unpaid breaks, on-call time, and travel time.How to Calculate Break DeductionsLearn how break time is deducted from work hours, typical break policies, and how to use a break time calculator.Shift Scheduling BasicsLearn how to calculate shift hours, handle rotating schedules, night shifts, and shift differentials.Common Payroll Calculation MistakesLearn about the most common payroll calculation errors, including rounding mistakes, overtime miscalculations, and break deduction errors.How to Use a Time CardLearn how to fill out a time card, calculate daily and weekly hours, and avoid common time tracking mistakes.Gross Pay vs Net PayLearn the difference between gross pay and net pay, what deductions are taken, and how to calculate each.How Time Zones WorkUnderstanding UTC, offsets, DST transitions, and the IANA time zone database. A complete guide to global timekeeping.
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Finance
13 published guides
How Mortgage Interest WorksLearn how mortgage interest is calculated, how amortization works, and how your monthly payments are structured.APR vs APYLearn the difference between APR (Annual Percentage Rate) and APY (Annual Percentage Yield) and how each affects loans and investments.ROI vs CAGRLearn the difference between simple ROI and CAGR, when to use each, and how to interpret investment returns accurately.How Extra Mortgage Payments Save MoneyLearn how making extra payments on your mortgage reduces total interest and shortens your loan term dramatically.How to Calculate Loan Payments ManuallyLearn the loan payment formula, amortization calculation, and how to calculate monthly payments for any loan.Understanding AmortizationLearn how amortization works, how each payment is split between principal and interest, and why early payments are mostly interest.How Savings CompoundLearn how compound interest grows your savings over time, the Rule of 72, and why starting early matters.How Inflation Affects Your SavingsLearn how inflation erodes purchasing power, what real returns mean, and how to account for inflation in savings goals.Mortgage BasicsUnderstanding mortgage payments, amortization, interest rates, and how extra payments save money.Understanding LoansPersonal, car, and general loans explained: interest rates, amortization, and comparing offers.Compound Interest ExplainedHow compound interest works, the Rule of 72, and why starting early matters for your investments.Savings GoalsHow to set savings goals, estimate time to reach them, and account for inflation in your financial planning.Return on Investment (ROI) ExplainedWhat ROI means, how to calculate it, and what makes a good return on your investments.