Thermostat Mounting Plate | Custom Size Cover Plate for Single Gang, Double Gang, or Open Wall Hole | 3" to 10" in 1/2" Steps

$28.50
Thermostat Mounting Plate - Custom Size, 3" to 10" in Half-Inch Steps ✔ Made in USA✔ Free Shipping Over $100✔ Ships in 2-3 Business Days✔ 30-Day Replacement Guarantee New thermostats are smaller than old ones. When you swap a big...
Availability: Out Of Stock
Product Type: Thermostat Plate

Thermostat Mounting Plate - Custom Size, 3" to 10" in Half-Inch Steps

✔ Made in USA✔ Free Shipping Over $100✔ Ships in 2-3 Business Days✔ 30-Day Replacement Guarantee

New thermostats are smaller than old ones. When you swap a big mercury or programmable unit for a modern smart thermostat, you are left staring at the outline: unpainted drywall, old anchor holes, torn wallpaper, and sometimes a gaping electrical box.

This plate covers all of it. Pick the exact height and width you need in half-inch steps from 3" to 10", tell us what is behind the wall, and we print it to order. The thermostat mounts on top; the mess stays underneath.

✔ PETG, made in the USA. Every plate is 3D-printed to order from PETG that will not warp, yellow, or crack. PETG tolerates temperature swings from -40°F to 140°F and accepts paint after a quick scuff-sand, so you can match it to your wall color exactly. Default is matte black; specify a Color Change Request at checkout for white, tan, or brown.

Pick Your Size

Two dropdowns, height and width, each running 3" to 10" in half-inch steps. Price scales with the plate area and its outline, so you pay for the size you actually order instead of a rounded-up standard size. Height and width are interchangeable in price: a 4" x 6" costs the same as a 6" x 4".

Plate Size Area Price
3" x 3" (smallest) 9 sq in $27.50
4" x 6" or 6" x 4" 24 sq in $35.00
5" x 5" 25 sq in $35.25
6" x 6" 36 sq in $39.50
7" x 5" 35 sq in $39.25
8" x 6" 48 sq in $44.00
10" x 10" (largest) 100 sq in $60.00

Every size prints as one solid piece. No seams, no two-part assembly, even at the full 10" x 10".

What Is Behind Your Wall?

The first dropdown tells us where the plate's mounting screws go. This does not change the price - pick whichever matches what you find when the old thermostat comes off.

  • Single Gang Box (3.281" screw spacing) - A standard 1-gang electrical box sits behind the thermostat. The plate gets two countersunk holes at 3.281" vertical center-to-center, matching the box's built-in screw tabs. Available from 4" tall and up, since the screw pair needs material above and below it.
  • Double Gang Box (3.281" V x 1.81" H) - A 2-gang box, common where an old intercom or a large thermostat with a transformer was mounted. The plate gets two pairs of countersunk holes at 3.281" vertical by 1.81" horizontal. Available from 4" tall and 4-1/2" wide and up, so the plate fully covers the wider opening.
  • Hole in Wall - No Box (4-corner screws) - No electrical box, just an opening in the drywall where the wires come through. The plate gets four countersunk screw holes 1/4" in from each corner, and you anchor it to solid drywall or studs around the opening. Available in every size from 3" x 3" up.

Every plate includes a center wire pass-through so your thermostat wires come cleanly to the front.

How to Measure

  1. Turn off power at the breaker for the furnace or air handler before you pull the thermostat.
  2. Remove the old thermostat from its base plate and unscrew the base from the wall. Leave the wires alone - just tuck them out of the way.
  3. Measure the area you need to cover - the discolored outline, old anchor holes, and any wall opening. Write down height and width.
  4. Add at least 1/2" on every side and round up to the next half inch. If the marked-up area is 4-1/4" tall by 5-1/8" wide, order 5-1/2" x 6".
  5. Check your new thermostat's footprint. The plate has to be larger than the thermostat base, or the base will overhang the edge.
  6. Look at what is behind the opening - a single gang box, a double gang box, or bare wall - and pick the matching Internal Opening.
  7. Not sure? Text a photo to 833-326-6868 with a tape measure in the shot and we will tell you what to order.
🛠 Hardware included. Every plate ships with the black flat-head countersunk #6 screws needed for the opening type you selected - two for a single gang box, four for a double gang box, four for the no-box corner mount - plus drywall anchors for the no-box option. Your thermostat's own base screws are not included; use the ones that came with your thermostat.

Installation

Tools needed: #2 Phillips driver. Drill optional, for pilot holes in plaster or hardwood. Painter's caulk optional.

  1. Confirm power is off at the breaker.
  2. Pull the thermostat wires through the center pass-through on the plate. Label them first if your old thermostat did not.
  3. Position the plate over the opening and check it covers the full outline. A level helps here - the plate sets the angle your thermostat will sit at.
  4. Drive the included #6 screws into the gang box tabs, or into the wall for the no-box option. Hand tight is enough; overtightening can dimple the plate.
  5. Mount your thermostat base on top of the plate using its own screws, feeding the wires through as you go.
  6. Wire and seat the thermostat per its instructions, then restore power at the breaker.
  7. Optional: caulk the plate perimeter with paintable acrylic and paint to match the wall for a fully finished look.

FAQ

Will this work with my thermostat brand?
Yes. The plate is a blank cover with a center wire pass-through - it does not attach to the thermostat, it sits behind it. Nest, ecobee, Honeywell, Emerson, Sensi, Wyze, and every other brand mount on top using their own base and screws. Just make sure the plate you order is bigger than your thermostat base.
How do I know what size to order?
Measure the discolored or damaged area left by the old thermostat, add 1/2" on every side, and round up to the next half inch. Both dimensions run 3" to 10" in half-inch steps, so you can get close to exact instead of jumping to a standard size.
Does the opening type change the price?
No. Single gang, double gang, and no-box all cost the same at any given size. Price depends only on the height and width you pick.
Why can't I order a 3" tall plate with a gang box?
A standard gang box puts its screws 3.281" apart vertically. A 3" plate has nowhere to put them. Gang box options start at 4" tall; the double gang option also starts at 4-1/2" wide so the plate fully covers the wider opening. If you need something smaller over a box, text us and we will look at it.
Can I paint it?
Yes. PETG paints well with standard latex or acrylic paint after a quick scuff-sand with 220-grit. Plates ship matte black by default; request white, tan, or brown at checkout.
Is the large size a two-piece plate?
No. Every size up to and including 10" x 10" prints as a single solid piece with no seam.
What if I need a size outside this range, or an odd shape?
Text 833-326-6868 or email shop@doorbellmount.com. We design and print these ourselves, so a one-off size or a custom screw pattern is usually no problem.

✔ Replacement Guarantee - The Right Plate, Guaranteed

Send a picture of your wall BEFORE you order. We will confirm the exact size and opening type that fits. If you order and it does not fit, we will send the correct plate at NO ADDITIONAL COST.

  • Before you order: Text or email pictures of (1) the wall with the old thermostat removed and (2) a tape measure across the area you need covered. We will confirm the size.
  • If the plate does not fit: Send a picture showing how. We will ship the correct replacement at no extra cost.
  • How to send pictures: Text/email 833-326-6868 / shop@doorbellmount.com (real person, not AI).
Questions? Text 833-326-6868 (real person, not AI) or email shop@doorbellmount.com. Plates ship in 2-3 business days from the USA.