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Unbilled time calculator

Small requests, quick calls and hours you forgot to log add up. Enter your hours, the share that slips through and your rate to see what it costs you.

The numbers are examples. Replace them with yours.

Hours you work for clients per week

Billable work only, not your own admin or sales.

Share that never reaches an invoice (%)

Time you forgot to log, small requests you didn't charge for, quick calls and messages.

Your hourly rate ($)

What you charge per hour, or your project price divided by its hours.

Working weeks per year

52 minus vacation and holidays.

Money not billed per year

$12,600

Per month: $1,050
Per week: $263
Unbilled hours per week: 3.5 h
Unbilled hours per year: 168 h

Estimates only. Nothing you type leaves your browser.

The formula

Unbilled hours per week = hours you work for clients per week × share that never reaches an invoice.
Unbilled hours per year = unbilled hours per week × working weeks. Per month is the yearly figure ÷ 12.
Money not billed = unbilled hours × your hourly rate.

A worked example

35 hours of client work a week with 10% never invoiced is 3.5 hours a week. Over 48 working weeks that's 168 hours. At $75 an hour, $12,600 a year never reaches an invoice, about $1,050 a month.

How to choose honest inputs

Guessing the unbilled share is hard because the whole problem is time you didn't notice. Run a timer on every bit of client work for two weeks, including calls, messages and five-minute fixes, then compare it with what you invoiced for those weeks. The usual leaks are hours you forgot to log, small requests you decided weren't worth charging, calls that turned into work, and time you logged but never invoiced.

Count only work you could have charged for. Your own admin, sales calls and learning aren't billable, so leave them out of the hours too. If you charge per project, use the project price divided by the hours it took as your rate.

Catching it in SoloWOS

Time Tracking runs a timer per project and turns billable hours into invoice line items. The weekly summary, on your dashboard and in a Monday email, lists billable hours from the last 180 days with no invoice and quotes accepted in the last 90 days that you haven't billed, each with a link to bill it. Ask the AI assistant "who owes me?" for invoices that are overdue.

IN SHORT

Money not billed per year = hours worked per week × share never invoiced × working weeks × hourly rate. At 35 hours a week, 10% unbilled, 48 weeks and $75 an hour, that's 3.5 hours a week, 168 hours a year and $12,600 you never invoiced, about $1,050 a month. Logging time as you work and invoicing from those logs closes most of the gap.

Prices and limits as of October 26, 2026.

Questions

What counts as unbilled time?

Client work that never made it onto an invoice: hours you forgot to log, five-minute changes you didn't think were worth charging, calls and messages that turned into work, and hours you logged but never invoiced.

How do I estimate my unbilled share?

For two weeks, run a timer on every minute of client work, calls and small fixes included. Then compare it with what you invoiced for the same weeks. The hours you didn't invoice divided by the hours you tracked is your share.

Should I bill for every small request?

That's your call, but make it on purpose. Some freelancers set a minimum, like 15 minutes, or add small requests to the next invoice. The expensive part is forgetting, not choosing.

How does SoloWOS catch unbilled time?

Time Tracking runs a timer per project and turns billable hours into invoice line items. Every Monday, the weekly summary lists billable hours from the last 180 days with no invoice and quotes accepted in the last 90 days that you haven't billed, with a link to bill each one. You can also ask the AI assistant "who owes me?"

What if I charge per project, not per hour?

Then unbilled time shows up as extra rounds and additions you didn't quote. Use your effective rate, the project price divided by the hours it took, as the hourly rate.

Related calculators

Log the time and catch what slipped

SoloWOS Time Tracking turns billable hours into invoice line items. The weekly summary flags unbilled hours and accepted quotes with no invoice, and the AI assistant tells you who owes you. 14 days free, no card needed · Then Basic for $2/month.

Start your free trial See Time Tracking