How Is a Pay Estimate Calculated? | HourStamp

The short answer

Most timesheets hand you a total and expect you to trust it. HourStamp keeps the working on the estimate itself: the hourly basis, the pay-period cycle dates, and the multiplier applied to each day. You choose a pay scheme and enter your base salary or rate; the app then works day by day, detecting whether a date is a weekday, a weekend, or a statutory holiday from a built-in holiday calendar and applying the matching overtime multiplier — weekday ×1.5, weekend ×2, statutory holiday ×3. Every amount is broken out item by item instead of collapsing into a single figure, so when a number disagrees with your payslip you have somewhere specific to point.

What it is not: every amount is an estimate for personal record keeping, not a wage determination or legal advice.

Why you want the working, not the total

The real question behind "how is this calculated?" is usually not curiosity. It is that the number in your bank account and the number in the app do not match, and you have no way to find out why. That situation has three common causes, worth separating before you go looking in the app:

• The day was classified differently. Your employer counted a date as a normal working day; the calendar says it was a statutory holiday. At ×3 versus ×1.5, the same eight hours is a large gap.
• The hourly basis is different. Two people on the same job with the same base salary can get different hourly rates depending on which divisor is used to turn a monthly salary into an hourly figure. This one is silent — no date looks wrong.
• Overtime hours were never recorded the same way. Rounded, estimated, or logged a day late. Nothing in the calculation is wrong; the input differs.

A total hides all three. An estimate that shows its hourly basis, its cycle dates and its multipliers turns the disagreement into a specific, answerable question — not that HourStamp's number is more authoritative than your employer's, but that you can see what each number was built from.

What the calculation actually does

The sequence is short, and each step is something you set rather than inferred:

1. Pick a pay scheme. HourStamp's first release focuses on monthly-salary overtime logging and estimates, so the base you enter is a salary or an hourly rate rather than a piece rate.
2. Enter the base salary or rate. This is the figure every later number is derived from.
3. Log shifts and overtime by pay period. Each entry is attached to a date, and the date is classified automatically against the holiday calendar.
4. Apply the multiplier for that day type — covered below.
5. Read the estimate. Cycle dates say which period the figure covers; the amount is itemised day by day.

Two properties of that pipeline matter more than they look.

The period is a boundary, not a label. Because estimates are reviewed by pay period, a figure always has a stated start and end. A monthly cycle running from the 25th to the 24th is a different calculation from one running calendar-month, and the cycle dates on the estimate are what tell you which one produced the number in front of you.

Nothing is a black box at the day level. Hourly basis, cycle dates and multipliers stay visible, and every wage is broken out item by item — so a mismatch is normally localised to one day or one item rather than to the total.

The hourly basis is where the argument lives

This is the part most apps hide, and it generates the hardest arguments — because it produces no visibly wrong day. Every date looks fine. The rate is just different.

Turning a monthly base salary into an hourly rate requires a divisor, and the choice in circulation is between 21.75 days / 174 hours and the statutory 166.64. Those are not interchangeable numbers, and the difference is applied to every hour of ordinary work as well as every overtime hour. Two ledgers built from the same shifts, overtime and base salary will produce different totals purely because of this one input.

HourStamp spells the choice out so you can make it yourself rather than picking one silently. Without knowing which basis produced your payslip figure, you cannot tell a classification error from a divisor difference — and those need different conversations with your employer.

Settle this before you interpret any mismatch: check one payslip against your estimate for a period where you worked no overtime at all. If the figures already disagree on straight time, the basis is the likely cause and the overtime multipliers are irrelevant until it is fixed.

Day type drives the multiplier

Once the basis is agreed, the remaining variable is what kind of day each entry falls on:

Day type	Overtime multiplier
Weekday	×1.5
Weekend	×2
Statutory holiday	×3

The day type is detected from a built-in holiday calendar rather than typed by you, removing the most error-prone manual step. It covers statutory holidays for 44 regions across 2024–2027, including the official mainland China schedule and Taiwan's labour holidays with their make-up workdays — weekdays nominally marked as holidays, which a tool that does not model them will miscount. See how the holiday calendars and make-up days work.

One more refinement, because a flat rate is not always right. Where the law distinguishes hours within a day, the multiplier can be tiered by hour — as Taiwan's Labor Standards Act does. A flat rate across the whole day gets that case wrong in a hard-to-notice way, exactly the class of error this app is trying to avoid.

Comparing the estimate against a payslip

Once your basis is settled, the estimate's remaining use is as a check on what you were actually paid. HourStamp supports this on device: photograph or choose a payslip, and it recognises common pay items and compares them against your ledger estimate.

The honest limit belongs in the same breath. If recognition is incomplete, rely on the original payslip and a manual review. Optical recognition narrows where to look; the original document is the authority. Treating a recognised total as settled is precisely how a mismatch gets missed — the items it failed to read are exactly the ones nobody then checks.

Why an old estimate does not quietly change

An estimate you can inspect is only useful if it still means the same thing weeks later. Three mechanisms protect that:

• Stamping a record freezes its device time, the pay settings captured at the time, and the day-level calculation. The record you read in November is the one made in November, under the pay settings then in force — not recalculated against whatever your rate is now.
• Explicit later edits retain a revision entry rather than overwriting, so a record that changed is visibly a record that changed.
• Ledgers are stored on your device by default, with no account required, and you can export a backup file manually. Worth knowing plainly: automatic iCloud sync is not promised as a first-release capability, so the manual export is the thing to actually use rather than assume.

One boundary stated exactly: a stamp is not third-party trusted time. It is your device's record of a moment — useful for personal record keeping, not a notarised timestamp. The personal record page covers what the stored trail and the PDF export do and do not establish.

What HourStamp does differently

The differentiator is not the arithmetic. It is that nothing in the chain is allowed to be implicit: the basis is chosen rather than assumed, the day type is detected rather than typed, the multiplier is visible per day, and the amount is itemised.

Two supporting choices matter for a tool holding an income record: no loans and no ads, and local-first with no account — camera, photos and location are used only after you grant permission, with no cross-app tracking.

The honest limits, so this is not read as more than it is:

• Recognition is an aid, not an authority. Incomplete reads stay incomplete.
• The first release centres on monthly-salary overtime. It is not a piece-rate or contract calculator.
• The PDF is a personal record summary, not a legal determination — not an arbitration or court finding of fact or amount.
• No automatic iCloud sync yet. Manual export is the backup story.
• The figures are estimates. They show what your own records imply, not what you are legally owed.

What to do with this

The decision you can now make is whether you want a timesheet that tells you a number, or one that lets you check it. If the second, the test is concrete: can you reproduce any figure from the hourly basis, the cycle dates and the per-day multipliers — and does the payslip comparison actually find a specific line that disagrees?

The free tier covers logging, estimates, ledgers and statistics, so you can answer that without paying. HourStamp Pro unlocks the shareable PDF personal record summary and is offered monthly, yearly, or as a one-time lifetime purchase — listed at $0.99 a month or ¥6, $3.99 a year or ¥28, and $9.99 once or ¥68.

If your answer is yes, HourStamp is on the App Store. Start by settling the hourly basis against one overtime-free period — that single step resolves more mismatches than any other.