Rack Layout Planner — Plan a Server Rack by Rack Units, Power & GPOs
A free printable rack layout planner. Choose a rack size in rack units (U), then add each mounted device with the number of U it occupies, a name, its power draw in watts and the number of GPOs (power outlets) it needs. Devices snap to the rack rails and are auto-numbered by U position; drag them up and down to reorder as you change your mind about placement. A running summary shows total U used, free U, total power and the total GPOs required. Print the rack elevation to exact scale or save it as a PDF.
Every rack build starts with the same three questions: does it physically fit, how much power will it pull, and how many outlets do I need at the back? A rack unit — one "U" — is the standard 44.45 mm slot that mounting holes are spaced around, and equipment is sold by how many of those slots it fills: a switch is often 1U, a typical server 1–2U, a UPS or disk shelf several U. This planner lets you lay the whole rack out on paper before you order a single rail. Pick the frame size — 6U, 12U, 24U, 42U and the other common heights, or type a custom number of U — and you get a scale elevation of the rails, numbered top to bottom (or bottom to top, your choice).
Then add your equipment. Each device gets a name, a height in U, the power it draws in watts and the number of GPOs it needs — that last field matters because a dual-PSU server wants two outlets, a simple switch wants one, and it is the total across the rack that decides how big a PDU (or how many) you must buy. Devices drop into the rack and stack up from the bottom; each one shows the U range it occupies (for example "U5–U6") so the labelling always matches the physical rails. Change your mind about the order? Drag a device to a new position or nudge it with the up and down buttons, and everything re-numbers and re-totals instantly.
The summary panel keeps the two numbers you actually have to hand to a colleague or a supplier: total power (with an estimated current draw at your supply voltage, so you can sanity-check the circuit and the UPS) and total GPOs required across all devices. It also tracks how many U are used and how many are still free, and warns you if the equipment you have added no longer fits the frame. Because the elevation is drawn in real millimetres and prints at exact physical scale, you can hold the printout against the real rack, or hand it to whoever is doing the install, and every slot lines up. It is the quick, no-nonsense way to plan a rack, document an existing one, or work out the power and outlet budget for a new cabinet.
Printing at exact scale
Every sheet is drawn in real millimetres and prints at exact physical scale. For accurate output, set Scale = 100% (Actual size) and Margins = None in your browser's print dialog. Not sure your printer is honest? Run the printer ruler test first to confirm 50 mm really measures 50 mm. Prefer a file? Use the PDF, PNG or SVG buttons to download the sheet instead of printing — PDF and SVG keep the exact dimensions, and PNG is a 300 DPI image.
Frequently asked questions
What is a rack unit (U)?
A rack unit, written "U" or "RU", is the standard vertical increment used to size rack-mounted equipment. One U is 44.45 mm (1.75 inches) of rack height. A 42U rack has 42 of these slots. Equipment is described by how many U it fills — a 1U switch, a 2U server, a 4U disk shelf — so planning by U tells you exactly what fits.
How do I choose the right rack size?
Add up the U of everything you plan to mount, then leave some headroom for growth and for airflow or cable-management gaps. This planner shows the used and free U as you add devices and warns you if you exceed the frame, so you can try a 24U against a 42U frame and see instantly which one your kit fits into.
Why does it ask how many GPOs each device needs?
A GPO (general-purpose outlet, i.e. a power socket) count per device lets the planner total the outlets you need at the back of the rack. A single-PSU device needs one, a dual-PSU (redundant) server needs two, and some appliances need more. The summary adds them all up so you can size your PDUs — you do not want to discover you are three outlets short on install day.
How is the power total and current worked out?
Each device has a power draw in watts; the planner sums them for a total load. Enter your supply voltage (for example 230 V or 120 V) and it also estimates the total current in amps (watts ÷ volts), which is handy for checking the circuit breaker and the UPS capacity. Treat these as nameplate estimates — real draw varies with load.
Can I reorder devices after adding them?
Yes. Drag any device up or down in the rack to move it, or use the ▲ and ▼ buttons on its card. Devices stack and snap to whole rack units, and the U labels (for example "U5–U6") re-number automatically so the elevation always matches the real rails.
Does it print to exact scale?
Yes. The rack elevation is drawn in real millimetres — each U is 44.45 mm — and prints at true physical size as long as you set the print dialog to 100% / Actual size with no margins. Use the calibration ruler page to confirm your printer isn't scaling.
Is this only for server racks?
No. It works for any 19-inch rack layout — network cabinets, AV racks, audio and broadcast racks, home-lab racks and comms cupboards all use the same U sizing, power and outlet planning.
Is it really free?
Yes. Every template on printsheet.io is completely free, with no sign-up, no account and no watermark. Plan as many racks as you like.
Can I save it as a PDF instead of printing?
Yes — choose “Save as PDF” as the printer in your browser's print dialog. The PDF keeps the exact millimetre dimensions.
Can I download it as an image (PNG or SVG)?
Yes — as well as Print and PDF, every sheet has a PNG and an SVG download button. PNG gives you a high-resolution (300 DPI) image at the exact page size; SVG is a scalable vector file that stays sharp at any size and can be edited in tools like Inkscape or Illustrator.
Which paper sizes are supported?
A4, A5, A3, A6, US Letter, Legal and Tabloid, in portrait or landscape. A tall rack prints best on A4/A3 portrait; use landscape or a larger sheet if your rack is very tall.