Front opening width: _____
Measure the inside width across the front opening of the firebox, from the usable inside edge on one side to the usable inside edge on the other.
Gas Log Measuring Guide
How to Measure Your Fireplace for Gas Logs (Step-by-Step Guide)
Selecting the right size gas logs for your fireplace isn't just about aesthetics—it's essential for safety, efficiency, and proper operation. Follow this simple guide to ensure you get the perfect fit for your hearth.
What You'll Need
- Measuring tape (preferably metal)
- Flashlight or headlamp
- Paper and pen to jot things down
Use the diagram as your visual reference, then record your numbers in inches.
Measure the inside opening of your firebox—not the existing logs—and record all four dimensions before choosing a set.
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Measure both widths
Record the front opening width and the rear width at the back of the firebox.
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Check height and depth
Measure the usable interior height and the floor depth from front to back.
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Allow room for a safe fit
Your burner and log set should be smaller than the firebox and meet the manufacturer’s clearance requirements.
Need more help?
View the full step-by-step measuring guide
The four usable firebox dimensions
Measure inside the firebox only. A fireplace can look large from the room and still have a smaller usable area once taper, frames, valves, and pipe locations are considered.
Rear width: ______
Measure the width across the back of the firebox at the narrowest usable point.
Height: _____
Measure from the firebox floor to the lowest point at the top of the opening.
Depth: _____
Measure from the front of the usable firebox floor straight back to the rear wall.
Most important
Measure usable firebox space, not just physical firebox size
If something projects into the firebox, measure to the obstruction, not through it. Gas piping, valves, door frames, and other permanent projections can reduce the space available for your burner system.
How to measure a tapered firebox
Many fireboxes are wider at the front than they are at the rear. That is why both widths matter. If the back wall is narrower, the rear width may determine the largest log size that fits.
Compare your measurements with the product page
After you measure, compare your numbers with the minimum fireplace dimensions listed on the product page for the specific gas log set.
Glass doors, frames, and front openings
If your fireplace has glass doors or a door frame, measure inside the firebox and floor area. If the frame or track is permanent and limits where the burner can sit, measure up to that frame or track.
If the doors are removable but the frame remains, the frame still matters. When in doubt, send photos with your measurements so AGW can review the setup.
Need help before ordering?
Let AGW review your fireplace before you choose
If your fireplace is unusual, your measurements are close to a product minimum, or you are not sure how to account for an obstruction, send photos and measurements for review before you order.
Frequently Asked Questions
What should I do if my measurements are close to the minimum?
What if the glass front on my fireplace doesn't come off?
I already have gas logs. Can I buy the same size again?
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Sometimes it is easier to speak with a fireplace specialist. Contact us and we will help you compare options, confirm compatibility, or answer questions before you buy.
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