Most organisations replace computers in one of two ways. Either a device is replaced when it fails, which means replacing it in a hurry and paying whatever is available, or everything is replaced at once every few years, which is a large invoice and a difficult fortnight.
A rolling plan is the middle route. Roughly a third of the estate each year, on a fixed month, budgeted as a routine line rather than a project. It is less exciting and considerably cheaper.
Start with a list, not a decision
Before deciding anything, write down what you have. One row per device: model, purchase or first use date, memory, storage type and size, and the person or role using it.
If you have any device management in place, that list already exists and can be exported. If not, an afternoon with a spreadsheet will get you most of the way, and the gaps you cannot fill are themselves useful information.
Add a column for warranty end. Out of warranty is not a reason to replace on its own, but it changes what a failure costs you in time.
Sort by constraint, not by age
Age is the obvious sort and the wrong one. A five year old machine used for email and a browser may be entirely adequate. A two year old machine with too little memory for the work it is doing is not.
Sort instead by what the person cannot currently do. The usual constraints are memory, a mechanical disk rather than a solid state one, and a processor that is no longer supported by the operating system you need to run.
Ask the users. People who wait for a machine every morning know it, and they will tell you faster than any monitoring tool. The ones who never complain are often the ones with the oldest equipment, so ask rather than wait.
Let support dates set the floor
Some of the schedule is decided for you. When an operating system or an application reaches end of support, the devices that cannot run its replacement stop being a preference and become a deadline.
Microsoft publishes these dates well in advance, which makes them easy to plan around and inexcusable to be surprised by. Put the relevant ones in the same spreadsheet, next to the devices they affect.
Where a device cannot be brought forward to a supported version, it belongs in the earliest year of the plan regardless of how well it currently runs.
Divide into three, then adjust
With the list sorted, draw a line after roughly a third. That is year one. The next third is year two, and so on.
Then adjust for two things. Keep teams together where you can, because replacing half a team’s machines creates support work in the gap between them. And pull forward anything where a failure would stop work outright, such as a machine driving a piece of equipment or holding something that only exists locally.
Anything only one person can use, or only one machine can run, should be at the front of the list whatever its age.
Decide the specification once
Agree two or three standard builds and buy those. A general build for most people, a heavier one for whoever works with large files, and a light one if you have roles that genuinely need only a browser.
Standardising is where the saving actually comes from. Fewer drivers, fewer surprises, spares that fit more than one person, and a support process that does not start from scratch each time.
Write down what each build is for. Without that, the heavy build spreads to everyone who asks nicely.
Put it in the calendar and in the budget
Pick a month and keep it. Many organisations choose a quiet period so the changeover does not land in their busiest weeks, and schools usually take the summer for the same reason.
Budget it as a recurring line. A third of the estate each year is a predictable number, and predictable numbers survive budget meetings far better than occasional large ones.
Plan what happens to the old machines
Decide in advance whether they are kept as spares, passed to lighter roles, donated or disposed of. Each route needs the data removed properly, and that step is the one most often skipped in a rush.
Keeping two or three as spares is usually worth it. A working loan machine turns a failure into an inconvenience rather than a lost day.
Review it once a year
Plans age. Someone joins, a team changes what it does, an application starts needing more than it used to. A short annual review of the same spreadsheet is enough to keep the order sensible.
We build and keep these lists for the organisations we support. There is more on our managed IT page and on devices and endpoint management. If you would like help turning your current estate into a three year list, tell us roughly how many devices you have and we will show you the shape of it.