Hourly billing: guide to tracking client hours

Hourly billing charges a client for the real time you spend on their work at an agreed rate. It protects you when project scope grows.

Track your hours, multiply by your rate, and send an invoice. Vague notes, surprise totals, and missing minutes are what slow payment.

Flat fee vs hourly billing

Picking between a flat fee and an hourly rate depends on who takes the risk of unexpected work.

A flat fee sets one fixed price for a defined deliverable. It rewards speed: if you finish a $3,000 design in ten hours, you earn $300 per hour. Flat fees work well when the job is clear and you have done that exact work many times. If the client asks for many revision rounds or changes direction, your hourly pay drops.

Hourly billing moves that risk to the client. It fits work where needs change as you go:

• Advisory and consulting: Technical guidance, code reviews, or advice calls without a fixed deliverable.
• Discovery work: Initial research and audits done before anyone can estimate project scope.
• Maintenance and fixes: Bug fixes, server updates, and repairs where diagnosis time varies.
• Work with external delays: Projects where approvals, feedback, and client assets take unpredictable time.

Track your time even on fixed-fee projects. Comparing the fee with your tracked hours shows whether your price covered the work. The guide on billable vs non-billable hours explains how to track both parts of your week.

How to calculate your hourly billing rate

Setting an hourly rate starts with the hours clients actually buy, not the total hours you spend at your desk.

Many people divide their target income by 2,000 hours, or by 2,080. That is 40 hours per week for 50 or 52 weeks. That math fails. No solo freelancer or consultant bills 40 hours every week. Unpaid work like sales, invoicing, and admin takes a large share of your schedule.

A solo freelancer might plan around 1,000 to 1,200 billable hours per year, depending on sales, admin, and leave.

To calculate your rate:

1. Set your take-home pay target: The net money you need for living expenses and personal savings.
2. Cover taxes and benefits: Income taxes, self-employment taxes where they apply, healthcare, and retirement. Tax is usually a percentage of the full amount. Raise take-home to cover tax. Do not add a flat number.
3. Add business costs: Software tools, computer gear, insurance, accounting, and office supplies.
4. Divide by annual billable hours: Divide the total required gross by your annual billable hours (for example, 1,000 hours).

Target take-home pay:   $80,000
Taxes and benefits:     $28,000
Business costs:         $12,000
Total required gross:  $120,000

$120,000 / 1,000 billable hours = $120/hour

The $28,000 line is an illustration of that tax-and-benefits bucket, not a tax formula. The freelance rate calculator grosses up take-home from a tax percent, then adds expenses.

Billing increments and the hourly billing chart

Timers record minutes and seconds, while invoices may use decimal or rounded hours. Divide minutes by 60 for decimal hours. An agreed increment is needed only when you round invoice hours.

Keep stored hours exact. Round a copy for the invoice, not the minutes in the tracker.

Two standards are common:

• Tenths of an hour (6-minute blocks): Common in legal work and accounting. Each 6-minute block equals 0.1 hours. Under ceiling rounding, a 14-minute call rounds up to 18 minutes (0.3 hours).
• Quarter hours (15-minute blocks): Common in design, development, and consulting. Each 15-minute block equals 0.25 hours. Under ceiling rounding, an 8-minute review rounds up to 15 minutes (0.25 hours).

Engineering has no profession-wide increment. Follow the contract.

Here is a ceiling rounding chart for client invoices. It rounds minutes up to the next billable block:

This chart is for client invoices. Do not always round employee punches up.

Minutes 13–15 and 16–18 both show 0.3 hours. The table lines 6-minute tenths up with 15-minute marks. To convert minutes by hand, divide by 60 (15 / 60 = 0.25 hours, not 0.15). 15 minutes on a timesheet does that conversion.

Rounding every small task on its own inflates bills. If you round three separate 2-minute emails up to 15 minutes each, the client pays for 45 minutes after 6 minutes of work. Group small related tasks into one block at the end of the day before applying your rounding rule.

Apply the increment once. Do not round each entry and then round the daily total again.

State your rounding rule in the agreement before you begin work. Say whether you round up or to the nearest block. Say whether the rule applies per entry or per day. For payroll rounding versus invoice rounding, read what is timesheet rounding.

How to bill hourly without client disputes

Clients rarely fight the hourly rate they agreed to pay. They dispute unexpected totals and vague descriptions.

A few clear habits stop invoice arguments before they start:

1. Agree on estimates and hour caps

Give your client an estimated hour range before starting work. For ongoing work, set a weekly cap (for example, “up to 15 hours per week without prior written approval”).

2. Warn clients before hitting limits

Do not surprise a client with a monthly bill that doubles your estimate. If unexpected system bugs or extra revisions push a 10-hour task toward 14 hours, tell the client at hour eight. Explain what slowed down the work and let them decide whether to approve extra hours or reduce scope.

3. Write outcome-based notes

A time entry should explain what you finished to someone who was not in the room. Vague notes invite questions.

• Weak note: “Research and coding (3.5h)”
• Strong note: “Built Stripe webhook listener and added test coverage for failed charges (3.5h)”

Use terms your client recognizes.

4. Separate rework caused by your mistakes

Testing, debugging, and fixing edge cases are normal billable work. Do not bill hours spent fixing your own careless mistakes, or learning a basic skill you claimed to have. Track that time so you can watch your pace. Leave it off the invoice.

5. Invoice on a regular schedule

Send invoices weekly or every two weeks instead of waiting for the end of the project. Regular billing keeps tasks fresh in the client’s memory, flags scope confusion early, and keeps unpaid balances small. For new clients, collect a deposit or prepaid hours before work starts.

Where TimeRetain fits

TimeRetain is a manual timer on your device. Give each client a timeline. Add a rate when you bill by the hour. Tag the kind of work.

There is no account. Hours stay on your device, and Sync is optional.

When you invoice, export a CSV and drop it into the invoices you already send. Stored time stays exact. You can round the export to match the increment in the agreement.

If you want to check the spreadsheet totals, paste the rows into the billable hours calculator.

Track client hours on your own device. Start, stop, export a CSV into the invoices you already send.

Start tracking →

Write the increment into the agreement, then start the first timer when the work begins.