Short answer
A standard door trim kit has two legs and one head, sized for doors up to about 36 x 80 in, and usually trims one side of the door. Buy a kit for one or two standard doors or a style with tricky parts, such as craftsman heads or rosettes. For a whole house, stock lengths are usually cheaper.
Kit or stock lengths?
| Trim kit | Stock lengths | |
|---|---|---|
| Best for | One or two standard doors | A room or a whole house |
| Cutting | Head often premitered; legs cut to length | Every piece cut from stock |
| Fit | Standard sizes only | Any size |
| Waste | Little | Depends on how lengths pack |
| Cost | Higher per foot | Lower per foot |
To compare, run your doors through the casing calculator: it tells you how many stock lengths a job takes, which you can price against kits.
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01Most common
Standard casing kit
Best for: replacing builder casing on one door
- Pieces
- 2 legs, 1 head
- Fits
- Up to about 36 x 80 in
- Material
- Pine, MDF or poly
- Colonial and ranch profiles are the usual choices
- Head often premitered at both ends
- Usually one side of one door
-
02Style
Craftsman trim kit
Best for: getting the craftsman head right without a table saw
- Pieces
- Legs, frieze, cap
- Joint
- Butted
- Finish
- Usually primed
- Head pieces sized to go together
- All square cuts
- Check whether the head arrives assembled
-
03Period
Fluted kit with rosettes
Best for: Victorian and traditional rooms
- Pieces
- Legs, head, blocks
- Example
- 3/4 x 3 x 84 in, 5 pieces
- Material
- Hardwood
- House of Fara lists an unfinished hardwood fluted kit with five pieces
- Corner blocks remove the miters
- Can be stained or painted
-
04No paint
Prefinished polystyrene kit
Best for: bathrooms and basements
- Finish
- Prefinished
- Fits
- Up to about 3 x 7 ft
- Material
- Polystyrene
- Sold as moisture resistant (maker claim)
- Nothing to paint
- Softer than wood, so it dents more easily
-
05Exterior
Exterior brick mold kit
Best for: one entry door
- Pieces
- 2 legs, 1 head
- Size
- 1-1/4 x 2 in
- Material
- PVC or wood
- PVC kits skip the painting
- Leave the leg ends off the sill
- Seal every joint
Before you buy a kit
- Measure the opening. Width between jambs and height from floor to head jamb. See how to measure for door trim.
- Count sides. Two kits per door if you trim both sides.
- Check the baseboard. Casing should be at least as thick as the baseboard at its outer edge.
- Order spares. One spare kit per few doors covers a bad cut or a damaged piece.
Next: how to install door casing.
Questions people ask
What comes in a door casing kit?
Usually two side casings and one head casing for one side of a door. Some kits mitre the head ends; craftsman kits include frieze and cap pieces; rosette kits add corner and plinth blocks. A House of Fara fluted kit, for example, has five pieces.
Do door trim kits fit both sides of the door?
Most kits trim one side. To trim both sides, buy two kits. Check the listing for the piece count.
Will a trim kit fit my door?
Check the maximum opening on the box against your door. Kits are commonly sized for doors up to 36 inches wide and 80 inches tall; one polystyrene kit lists openings up to 3 by 7 feet. Taller or wider doors need stock lengths.
Last reviewed October 12, 2026. Profiles, sizes and listings change; check the product details before you buy, and follow the maker’s instructions.