How to Get Better at Estimating Time Accurately

Many productivity and time management experts recommend time blocking as a great way to be hyper-productive. If you’re a professional who spends a lot of time in meetings, your days can easily be eaten up by meetings and meeting transitions. When you need to accomplish deep work, time blocking is crucial. 

Experts often skip over a prerequisite for time blocking, though. You need to get good at estimating time accurately.

Does this scenario sound familiar to you? It’s Monday, and you have a big proposal due by Friday. Your week is pretty busy so you block 2 hours on Wednesday afternoon to knock out the proposal. Wednesday afternoon comes and you work hard from 1 pm to 3 pm. When 3 pm rolls around, you’re not even halfway done with the proposal. You needed input from someone else, you couldn’t find the template, or it just took longer than you expected.

You might wrongly draw the conclusion that time blocking doesn’t work for you and give up on it before you really start. But in actuality, it was the estimation that was the issue, not the time blocking itself.

I’ve been a consultant for over a decade, and I spend a big chunk of time estimating large-scale projects. Over the years, I’ve learned how to estimate time accurately. These are some of my favorite tricks for estimating time accurately.

Track the time for tasks you do frequently

If you do some tasks frequently, start tracking how long they take. How many hours does it take to write a 2,000 word article, create a reporting dashboard, or build a forecast model? Keep track of patterns and make sure to note the details of each project. Over time, you should be able to build a good picture of how long your recurring tasks take.

This tip is great for people who have relatively predictable jobs and tasks. Even if your job is variable, you may still see patterns. For example, I might be able to find patterns in how long it takes to build a reporting dashboard, even if I’m doing it for multiple customers in different industries.

To take this tip to the next level, write down about how long you expect a task to take. Then note how long it actually took afterward. What was different? Were you missing pre-work or did it simply take longer than you thought it would? This observation and refinement is crucial to getting really solid estimates.

Ask for feedback on how long a task will take

I always ask for feedback before I send out a time estimate. I’ll talk to multiple people with different perspectives – more experienced, less experienced, different skill sets, different parts of the organization. Because these folks have different perspectives, they frequently spot gaps or problems that I’ve missed. While I’m thinking about the complexity of the models, a data expert is worrying about how long it will take to take in and cleanse the data. An account executive knows about the client’s internal politics that will require a longer project ramp-up period. And so on.

These discussions usually don’t take much time and they’re extremely valuable. Obviously you want to scale this to the size of your estimate. When I’m working on a multi-month project estimate, I’ll spend hours validating the estimate. If you’re working on time estimate for a short project (a few days), just a quick check with a trusted colleague should suffice. Don’t spend a huge amount of time on this but a little feedback can go a long way.

Do top-down and bottom-up task time estimates, then reconcile

For an extra sanity check, I really like to build estimates both from the bottom up and then top down. Then you can compare both estimates to see if they match.

First, do a quick gut check. How long do you think this project or task will take? Use big round numbers and don’t overthink it. 

Next, break the task down into sub-tasks. Make a list of the sub-tasks and then assign effort to each sub-task. Next, add up the effort for all of the sub tasks and compare the final number to the high level top-down number.

In general, use the highest estimate. When you start getting practiced at this, your two numbers should be pretty close. For now, just go with the higher estimate which will end up being more conservative.

Identify risks, variables and pre-work for tasks

Whenever you’re estimating how long a task will take, and especially when you plan to block time to work on something, it’s important to be prepared ahead of time. You don’t want to sit down to work on a task, only to realize you’re missing some important piece of information. So do yourself a big favor and note any pre-work ahead of time. You should plan your time blocks a few days to a week in advance to make sure you have adequate time to request input, ask questions, and get what you need to be ready to hit the ground running during your time block.

It’s also helpful to note risks and variables. For example, if you’re working on a data science project but haven’t looked at the data yet, it’s possible there will be data quality problems or missing data. Call this type of thing out ahead of time and plan for it in your time blocks. If there’s a big variable, allow time between your first time block and your deadline to address issues that are likely to arise. 

Add a big margin to your time estimates at first

You should always add a big margin when you’re first estimating time for tasks. I recommend taking the estimate you’ve arrived at using the first four steps and doubling it, at first. You should follow the first tip and track task effort. Over time, you can refine your estimates and reduce the margin as possible. Even when you’re skilled at making time estimates, you should still add a buffer to account for unexpected issues, usually no less than 20%.

Tips for estimating time accurately

These tips will help you get better at estimating time so you can be realistic about your time blocking. Explicitly estimating and tracking your tasks will help you use your time blocks effectively. You can also take care of any pre-work tasks so you don’t waste your deep work time looking for things or asking people for input.

Another side benefit of getting better at estimating time accurately is that you’ll be much less likely to overcommit yourself. In any given week, you’ll have a good idea of how much you can accomplish. This makes it a lot easier to talk with your colleagues about priorities. If you know that your monthly reporting is going to take 3 days this week, and someone also asks you to write a proposal (which will also take 3 days) it’s very easy to call that out. Having data and reliable estimates is the foundation upon which so much time management is based, and most people don’t practice this skill. The better you get at estimating how long a task will take, the more in control you’ll feel over your schedule and over your time.