What Size Gas Insert Do I Need?
Proper sizing ensures your new insert delivers enough heat and just the right amount of heat without overheating the room or wasting fuel. Here's how to choose the best fit for your home and firebox:
Step 1: Measure Your current Fireplace Opening. Measure width, height, and depth at multiple points. Your insert must be slightly smaller to allow clearance for the vent collar and surround trim. Also, measure the floor hearth in case you have less than the minimum required by the manufacturer.
Step 2: Estimate Room Size & Heating Needs. Use the guide below to match your square footage to an ideal BTU range. Adjust upward for drafty homes or high ceilings.
Room Type |
Sq Ft |
Recommended BTUs |
Example Model |
Small Den / Bedroom |
300 – 800 |
10,000 – 20,000 |
SÓLAS TWENTY6 |
Living Room / Family Room |
800 – 1,500 |
20,000 – 30,000 |
Valor G4 |
Large Great Room |
1,500 – 2,500 |
30,000 – 45,000 |
Mendota FV44i |
Tip: Modern homes need less BTU than older homes. Go low if you have spray foam insulation and tight windows; go high if your home is drafty or has high ceilings.
If you plan to install a TV above the gas fireplace insert, check the ceiling height and distance to a wall. Then, you need a mantle in between. If it’s a combustible mantle, make sure you check clearances above the glass in the manual. If it’s a non-combustible mantle, you can lower it and have more space. This mantle will deflect the heat and create a safe place above it for the TV.
Popular Styles: From Classic Logs sets to Modern Frameless Glass
Today's gas inserts come in a range of design themes to suit and warm up your space. Whether you're restoring a traditional fireplace opening or modern house, there's a look that fits.
Traditional Brick gas fireplace inserts
For traditional looking homes, a classic log set with brick or split-stone interior panels gives the feel of a true wood fire with controllable warmth without the mess or ashes. The Archgard Chantico 36 is a customer favorite with arched fronts and real-wood log realism.
Contemporary Clean-Face Look gas fireplace inserts
In new constructions, opt for a minimalist insert with no traditional accessories. The SÓLAS TWENTY6 features black glass media, reflective panels, and ambient lighting for a dramatic modern effect.
Transitional Style
Want the best of both worlds? The Regency GI33 blends subtle curves, rich ember beds, and a slimline faceplate—perfect for farmhouse-modern or craftsman renovations.
Design tip: Choose trim widths that match your mantle legs, and consider matte finishes to avoid glare on glass. Our team can help you match surround options to your décor.
Which gas insert size and style should I choose for my home