How to use the project scope creep calculator
As you probably know, scope creep never shows up as a line item; it just quietly eats into your time and revenue. This unbilled work calculator shows you exactly how many billable hours you are losing and what they’re really costing you.
In just a matter of seconds, you’ll see how much time (and money) you’re leaving on the table, and what to do about it.
You can run calculations in USD, EUR, or GBP, depending on your currency. Results are based on a standard 240 working days per year, to give you a consistent view of your time and revenue. How much you actually recover, of course, depends on how you apply these insights in your day-to-day work.
Choose how you want to calculate
Before you start, pick the mode that best suits you.
If you’re not sure about the exact numbers of unbilled hours, go with Help me estimate. It’s designed to guide you through the most common sources of scope creep using rough inputs. No need to overthink this step; quick estimates are enough.
If you already know your numbers, choose I know my numbers and enter your total unbilled hours directly.
No matter which option you choose, you get a clear picture of the billable hours you’ve lost.
Set your hourly rate and work time
Next, enter how much you charge per hour and how many hours you work each week.
This step turns your lost time into real numbers; thanks to this data, our undercharging calculator can show lost hours and actual lost revenue. Keep in mind that you can use USD, EUR, or GBP—whatever works best for your workflow.
Enter your unbilled time
It’s time you entered your unbilled hours.
Now, if you chose Help me estimate, this is where you break down your week. You estimate how much time you spend on things that don’t get billed, including:
• Meetings
• Messages (Slack, email, etc.)
• Quick client requests
• Revisions
• Other work
For each category, you use a rough scale, and there’s no need to obsess over being superprecise. The goal is awareness, not perfection. And keep in mind that the “other” category is where everything else goes, like internal chaos, small tasks, interruptions, and all those tiny things that don’t feel like much but add up fast.
As you fill this in, the calculator adds everything up and shows your total unbilled hours per week. It also puts that number into perspective by showing what percentage of your working time is lost to scope creep. So, if you work 40 hours a week and estimate 10 hours of unbilled work, that’s 25% of your time going unpaid.
If you chose I know my numbers, you skip the breakdown and go straight to the point. Just enter how many hours you work per week, but don’t bill. Include everything—meetings, messages, revisions, quick requests, and any extra work that wasn’t invoiced.
See what scope creep is really costing you
Once you’ve added your revenue, team members, and project-related costs, the calculator does all the math. In seconds, you’ll see exactly how profitable this project really was, based on real numbers.
Here’s what you’ll get exactly.
Unbilled hours per week
This number shows how many hours you work every week without getting paid for them. It’s your total scope creep in time, and it also shows what percentage of your week that represents.
For example, if you charge $100/hour, work 40 hours per week, and roughly estimate 3 hours in meetings, 2h on messages, 2h on quick client requests, 3h on revisions, and none on other small tasks, that totals 10 unbilled hours per week. That’s also 25% of your working time slipping away.
Revenue left on the table
This number shows the money tied to your unpaid work.
Let’s use the previously mentioned example:
• Hourly rate: $100/hour
• Total work hours per week: 40
• Unbilled hours per week due to scope creep: 10 hours/week
The calculator does the following calculations:
1. Weekly lost revenue using the formula:
Weekly lost revenue = Unbilled hours per week × Hourly rate.
Following our example, it’s 10 hours × $100 = $1,000 per week.
2. Monthly lost revenue using the formula:
Monthly lost revenue= Weekly lost revenue × 4.33 (assuming 4.33 weeks per month).
Following our example, it’s 1,000 × 4.33 = $4,330 per month.
3. Yearly lost revenue using the formula:
Yearly lost revenue = Weekly lost revenue × 52 (assuming 52 weeks per year).
For our example, it’s 1,000 × 52 = $52,000 per year.
Seeing all these numbers in dollars (or euros or pounds) makes it clear that scope creep costs you time and also real money.
Equivalent free work
To make all these numbers even more tangible, the calculator converts your lost hours into days.
Here’s how it works using the previously mentioned example:
• It first calculates total unbilled hours per month (assuming 4.33 weeks per month) using the formula: Total unbilled hours per month = Total unbilled hours per week × 4.33. In our case, it’s 10 × 4.33 = 43.3 hours/month.
• It then calculates the workday equivalent using the formula: Equivalent free work = Unbilled hours per month / Hours per workday. In our case, it’s 43.3 / 8 ≈ 5.4 days/month (if you normally work for 8 hours per day).
So in this example, scope creep is making you work 5.4 days every month for free; time you could otherwise spend on new projects, rest, or billable work.
💡 Note: If you want to stop guessing unbilled hours, Memtime can automatically track everything you work on in the background, including meetings, messages, revisions, client requests, and even small hidden tasks.
By capturing all your time without your input, it gives you a fully accurate picture of your workdays and billable hours, so you can protect your time and invoice confidently.
