Billable Hours Calculator

Billable Hours Snapshot

{{ formatHours(totals.billableHours) }} billable {{ formatHours(totals.nonBillableHours) }} non-billable {{ formatMoney(totals.writeDownAmount) }} write-down {{ roundingLabel }} {{ realizationBadge }} {{ rateBadge }}

Entry mode:

Use duration for timer totals; use clock rows when start and end times need review.

Rounding increment:

Pick the policy unit: 6 minutes for tenths, 15 minutes for quarter-hour billing.

Rounding mode:

Choose nearest, up, or down to match the client billing rule before reviewing totals.

Write-down mode:

Enter write-downs as percent, flat currency, or hours removed using this selected mode.

Time entries:

Add one task per row; duration rows accept decimal hours/minutes, clock rows use HH:MM times.

Date	Client / project	Description	Duration	Unit	Start	End	Rate	Billable	{{ writeDownColumnLabel }}	Remove

{{ warning }}

Currency symbol:

Enter one symbol or short code, such as $, RM, EUR, or GBP.

Group totals by:

Group client totals by project, date, or billable status for the review table.

Allow overnight clock rows:

Turn on only when clock rows can cross midnight; leave off to catch reversed times.

Export label:

Use a short client, matter, or billing-period label for CSV and JSON output.

Entry	Recorded	Rounded	Rate	Gross	Net	Copy
{{ row.project }} {{ row.date }} · {{ row.description }}	{{ formatHours(row.rawHours) }}	{{ formatHours(row.roundedHours) }}	{{ formatMoney(row.rate) }}/hr	{{ formatMoney(row.grossAmount) }}	{{ row.billable ? formatMoney(row.netAmount) : 'Non-billable' }}

Group	Entries	Billable hours	Write-down	Subtotal	Copy
{{ row.label }}	{{ row.entries }}	{{ formatHours(row.billableHours) }}	{{ formatMoney(row.writeDownAmount) }}	{{ formatMoney(row.netAmount) }}

No billable rows with positive amounts.

Entry	Adjustment	Gross	Net	Copy
{{ row.project }} {{ row.description }}	{{ row.adjustment }}	{{ formatMoney(row.grossAmount) }}	{{ row.billable ? formatMoney(row.netAmount) : 'Non-billable' }}

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Billable hours turn recorded work time into an invoiceable quantity, which makes them more than a timesheet total. A short call, drafting session, meeting, review block, or support handoff may be recorded in raw minutes, but the billed amount usually depends on a separate policy: which rows are billable, how time is rounded, what hourly rate applies, and whether any write-down is taken before the invoice goes out.

The same recorded minutes can produce different invoice amounts when the billing rule changes. Sixth-hour billing treats six minutes as one tenth of an hour. Quarter-hour billing treats 15 minutes as the smallest unit. Rounding up, down, or to the nearest increment can turn a brief task into a larger or smaller decimal-hour entry, so the rule should come from the engagement letter, client billing guideline, internal policy, or contract rather than habit.

Recorded time, billing policy, and write-downs affect different parts of the invoice calculation.

Clean classification matters as much as arithmetic. A non-billable row may still matter for staffing analysis, client service, or internal review, but it should not add to the invoice subtotal. A billable row with a zero rate may be a deliberate courtesy, a missing rate, or a data-entry mistake. A row with a rate but a non-billable flag is another common review signal because the rate looks chargeable while the billing flag says otherwise.

Common billable-hours terms and invoice meaning
Term	Plain meaning	Why it matters
Recorded time	The actual duration before billing policy is applied.	It is the audit trail for what was worked.
Rounded time	The duration after applying the selected billing unit.	It drives the chargeable hours on hourly invoices.
Write-down	A reduction taken before the final billed amount.	It explains the gap between work value and invoice value.
Realization	Net billed value divided by gross billable value.	It shows how much billable value survived review.

Write-downs are not the same as non-billable time. Non-billable time is excluded from the invoice value from the start. A write-down starts from a billable row and then reduces the amount, often because of budget limits, client guidelines, duplicated effort, training time, a courtesy discount, or senior review. Keeping those ideas separate makes the invoice easier to explain and makes realization easier to track.

Billable-hours math is useful only when the policy behind it is valid. Payroll rules, legal-fee rules, government time-and-materials contracts, and private engagement terms can all use different standards. A worksheet can show what a chosen rule does to the numbers, but it cannot decide whether that rule is allowed, fair, or contractually approved.

How to Use This Tool:

Start with the way the time was captured, then apply the billing policy before reviewing invoice totals.

Use the live timer controls when you need to capture a new work session. Start, Pause, and Log create a duration row from the elapsed timer, using the first existing billable rate when one is available.
Choose Entry mode. Duration rows accept decimal hours or minutes. Start and end time rows accept clock times in HH:MM format.
Add one Time entries row per client, project, task, day, or invoice line. Fill Date, Client / project, Description, Duration or Start and End, Rate, and the Billable checkbox.
Set Rounding increment and Rounding mode before judging totals. The available increments run from 1 minute through 60 minutes, and the mode can round to the nearest increment, up, or down.
Choose Write-down mode, then enter each row's write-down as a percent, flat amount, or billable hours removed. Leave the value at zero when no adjustment applies.
Open Advanced when you need a different Currency symbol, grouping by Date or Billable status, overnight clock rows, or an Export label for files.
Review warnings before using the subtotal. A reversed clock row, zero hourly rate on billable time, capped write-down, or rated non-billable row can change the invoice interpretation.

Use Line Items for row-level audit, Client Totals for rollups, Billing Realization for gross-versus-net comparison, Write-down Ledger for adjustment review, and JSON when you need a structured handoff.

Interpreting Results:

The large amount at the top is the net invoice subtotal after write-downs. The nearby badges show rounded billable hours, rounded non-billable hours, total write-down amount, the active rounding policy, realization percentage, and the effective hourly rate after adjustments.

Check Line Items when a subtotal looks wrong. The Recorded column shows the raw time. The Rounded column shows the time after the selected increment and rounding direction. Gross is calculated from rounded billable hours and the hourly rate. Net is the amount left after the row's write-down, while non-billable rows show as Non-billable instead of adding to the invoice.

Client Totals roll up the same row math by client/project, date, or billable status. The subtotal column is sorted from highest invoice value to lowest.
Billing Realization compares gross and net amounts for groups that have billable value or write-downs. A lower net bar points to discounts, removed hours, or other reductions.
Write-down Ledger is the fastest place to review why a row moved from gross to net, including percent, flat amount, hours removed, and non-billable exclusions.
The realization badge changes review color at 90% and 75%. Treat the color as a review cue, not as a universal benchmark.

A clean subtotal still needs a policy check. Match the rounding increment, rounding direction, hourly rate, and write-down treatment against the client agreement or billing guideline before sending an invoice.

Advanced Tips:

Set the rounding increment and direction before entering final review rows. Changing from nearest sixth-hour billing to round-up quarter-hour billing can move both gross amount and write-down size.
Use the live timer for new work sessions and duration rows for imported totals. Clock rows are better when start and end times need review or when an overnight span may be disputed.
Group by client/project for invoice review, by date for daily timekeeping checks, and by billable status when you need to separate chargeable work from internal support time.
Choose the write-down mode that matches the review note. Percent write-downs explain proportional discounts, flat amounts explain invoice caps, and hours removed explain reduced chargeable time.
Use the realization chart after row warnings are clear. A low realization bar is meaningful only after reversed times, zero rates, capped write-downs, and non-billable rate conflicts have been reviewed.

Technical Details:

Billable-hours calculation begins by converting every row to minutes. Duration rows use the entered unit. Clock rows subtract the start time from the end time, and an overnight option adds 24 hours only when the row intentionally crosses midnight. Negative or invalid clock spans produce a warning and contribute zero minutes until corrected.

Rounding is applied before invoice value is calculated. That ordering matters because a 7-minute row at a 6-minute increment can become 12 minutes when rounded up, 6 minutes when rounded to the nearest increment, or 6 minutes when rounded down. The hourly rate is then applied to the rounded billable hours, not to the raw minutes.

Formula Core:

The core calculation uses minutes as the common unit, then converts rounded minutes back to hours for invoice math.

H_{raw} = \frac{M_{raw}}{60}

M_{rounded} = q R (\frac{M_{raw}}{q})

{Gross}_{i} = B_{i} \frac{M_{rounded,i}}{60} {Rate}_{i}

{Net}_{i} = \max (0, {Gross}_{i} - A_{i})

Realization = \frac{\sum {Net}_{i}}{\sum {Gross}_{i}}

Formula variables for billable hours calculation
Symbol	Meaning	Source or rule
`M`_raw	Raw minutes for one row	Duration input, or end clock time minus start clock time
`q`	Rounding increment in minutes	1, 5, 6, 10, 15, 30, or 60 minutes
`R`	Rounding function	Nearest, up, or down
`B`_i	Billable multiplier	1 for billable rows, 0 for non-billable rows
`A`_i	Write-down amount	Calculated from percent, flat amount, or hours removed

Rounding and Write-down Rules:

Billable hours rounding and write-down rules
Rule	Calculation behavior	Review consequence
Nearest increment	Raw minutes divided by the increment are rounded to the nearest whole unit; halfway positive values round upward.	Small differences near the midpoint can change the rounded hours.
Round up	Any positive partial increment moves to the next whole increment.	Short tasks can increase more than users expect.
Round down	Partial increments are discarded.	Brief work can become zero if it is below the selected unit.
Percent write-down	The percent is limited to 0% through 100% of the row gross amount.	Values above 100% are capped and warned.
Flat amount write-down	The entered amount is limited to the row gross amount.	The row net amount cannot go below zero.
Hours removed	Removed hours are limited to the rounded billable hours, then multiplied by the rate.	Overstated hour reductions are capped and warned.

Money values are rounded to cents. Displayed hours use two decimal places, while CSV and JSON hour values preserve four decimals for audit handoff. The currency symbol affects labels only; it does not convert exchange rates, add tax, apply retainers, or model collections after the invoice is sent.

A row contributes to realization only when it has billable gross value. Group realization is calculated as net amount divided by gross amount for the same group, so a group with heavy write-downs can show a low realization rate even when the total number of recorded hours is high.

Accuracy and Privacy Notes:

Use the results as an invoice review worksheet, not as legal, payroll, tax, or contract advice. The calculator applies the settings you choose, so policy accuracy depends on choosing the increment, direction, rate, billable status, and write-down mode that match the governing agreement.

For employee wage records, payroll rounding may be governed by labor rules that differ from client billing practice.
For legal and other regulated professional services, fee reasonableness, rate disclosure, and client guidelines can matter as much as the arithmetic.
For time-and-materials or labor-hour contracts, daily timekeeping records and contract rate rules may control what can be billed.
Rows are calculated in the browser without uploading time entries for calculation. Exported CSV, DOCX, chart, and JSON files can still contain sensitive client or matter details.

Worked Examples:

Short client call with sixth-hour billing. A 7 minute Duration row at $100/hr with a 6 minute increment and Round up becomes 0.20 Rounded hours. Line Items shows 0.12 hr Recorded, 0.20 hr Rounded, $20.00 Gross, and $20.00 Net.

Review write-down on a memo. A 1.00 hour billable row at $100/hr with Write-down % set to 10 produces $100.00 Gross and $90.00 Net. Billing Realization shows a 90.0% realization rate, which reaches the green badge threshold; a slightly larger write-down would move the review cue into the middle range.

Overnight clock entry. A Start and end time row from 22:30 to 01:15 is warned as reversed when Allow overnight clock rows is off. Turning that option on treats the row as 165 raw minutes. With 15 minute rounding up and a $180/hr rate, Line Items shows 2.75 Rounded hours and $495.00 Net before any write-down.

Rated time marked non-billable. An 18 minute internal admin row at $125/hr with Billable unchecked still appears in time analysis as 0.30 rounded non-billable hours when using a 6 minute increment. The Net column shows Non-billable, the subtotal does not increase, and a warning explains that a rate on non-billable time is excluded from the subtotal.

FAQ:

Can I mix timer, duration, and clock entries?

Yes. The live timer logs a duration row, and Entry mode controls whether the editable table uses duration fields or start and end clock fields for the current review.

Why did a short entry round to a larger amount?

Rounding happens in the selected billing increment before the rate is applied. With Round up, any positive partial increment moves to the next full unit.

What should I do when a clock row says the end time is before the start time?

Correct the times if they are reversed. Turn on Allow overnight clock rows only when the work really crossed midnight.

Can a write-down make a row negative?

No. Percent, flat amount, and hours-removed write-downs are capped so the row net amount cannot fall below zero.

Does the currency symbol convert money?

No. The Currency symbol field changes display labels and export labels only. Rates, gross amounts, write-downs, and subtotals keep the same numeric values.

Are time entries uploaded for calculation?

No. The calculation runs in the browser. Treat copied rows and downloaded files carefully because they can include client names, project labels, descriptions, and billing amounts.

Glossary:

Recorded time: The raw duration before rounding, shown in the Recorded column.
Rounded time: The billable duration after applying the selected increment and direction.
Write-down: A reduction from the gross row amount before the net subtotal is calculated.
Gross amount: Rounded billable hours multiplied by the hourly rate before write-downs.
Net amount: The amount left after write-downs, or zero for non-billable rows.
Realization: Net amount divided by gross amount, expressed as a percentage.
Effective hourly rate: Net invoice subtotal divided by rounded billable hours.

References:

29 CFR 785.48, Use of Time Clocks, Electronic Code of Federal Regulations, updated May 15, 2026.
FAR 52.232-7, Payments under Time-and-Materials and Labor-Hour Contracts, Acquisition.gov, Nov. 2021.
ABA Model Rule 1.5: Fees, American Bar Association, Apr. 14, 2020.
How to Calculate Realization Rate?, BQE CORE Help Center, June 13, 2025.