How to Read the Label on the Back of a Stove

Every stove sold new in the United States carries a certification label, and it is the only part of the specification nobody in a showroom is tempted to round in their favour. It is also mostly ignored, because the numbers on it need about two minutes of explanation.

Here is that explanation.

Key figures

• 4.5 g/h Earlier EPA Step 1 emissions limit
• 2.0 g/h EPA Step 2 crib-wood emissions limit
• 2.5 g/h EPA Step 2 cord-wood emissions limit

Grams per hour

This is the emission rate: the smoke the stove produces per hour of burning under a standardised test.

The history matters because it explains the range of stoves you will see second hand:

• Uncertified stoves: 15 to 30 grams per hour, according to EPA.
• Step 1 certified, under the 2015 standards: no more than 4.5 g/h.
• Step 2 certified, from 15 May 2020: 2.0 g/h tested with crib wood, or 2.5 g/h tested with cord wood.

• Older uncertified stove15 to 30 g/h
• Step 1 certified, 20154.5 g/h
• Step 2, cord wood test2.5 g/h
• Step 2, crib wood test2.0 g/h

US EPA Burn Wise. The uncertified figure is the upper end of EPA's stated 15 to 30 g/h range for older stoves. Step 2 limits are 2.0 g/h on crib wood and 2.5 g/h on cord wood.

The practical reading: replacing a stove from the 1980s with a current one is not a marginal improvement. It is roughly a tenfold reduction in smoke, which shows up as less creosote in the chimney and less smoke in your neighbour’s garden.

Crib wood and cord wood

Two test fuels, and the difference is worth knowing when comparing models.

Crib wood is dimensional lumber, cut 2x4 or 4x4 and stapled into a uniform stack. It burns in a repeatable way, which is good for a laboratory and unlike anything in your woodshed.

Cord wood is ordinary split firewood. EPA describes it as a better measure of how a heater will perform in homes.

So when you compare two stoves, check which test each number came from. A 2.5 g/h cord wood result and a 2.0 g/h crib wood result are both compliant, and they are not directly comparable.

Efficiency

Newer labels carry an efficiency figure as well. Two cautions:

• Efficiency and emissions are different things. A stove can be clean and unimpressive at delivering heat into the room, or the reverse.
• Efficiency is quoted in more than one way. The higher heating value basis, which is what the federal tax credit used when it existed, gives a lower and more conservative number than other conventions. When a brochure quotes a much higher figure than the label, that is usually why.

Heat output

Showrooms quote BTU per hour, often as a maximum achieved in a laboratory with a full load and a wide-open air control. Treat it as a ceiling rather than a working figure, and size the stove by the space it will heat rather than by the biggest number available. EPA’s sizing guidance is deliberately coarse: small stoves for a family room or seasonal cottage, medium for small or energy-efficient houses, large for bigger open-plan or leaky older houses.

What the label does not tell you

• How it will behave on your chimney. Draught depends on height, location and the flue’s size.
• How clean it will be in your hands. A certified stove burned on wet wood with the air shut down produces smoke that no certification prevents.
• Whether it fits your clearances. That comes from the manufacturer’s listed installation instructions.
• How long the catalyst will last, if it is a catalytic model. EPA notes a catalyst can last more than six seasons with proper use, or break down in as little as two if the stove is over-fired.

The short version for a showroom visit

1. Ask to see the certification label, and photograph it.
2. Note the grams per hour and which test fuel it used.
3. Note the efficiency figure and ask on what basis it is stated.
4. Ask for the manufacturer’s listed clearances and floor protection requirements.
5. Ask what flue diameter the model requires, and compare it to your chimney.
6. Then talk about the finish, the glass and the colour.

Related reading: A Pellet Stove Service Plan Needs an Equipment List and When an Old Stove Is Worth Replacing.

Questions people ask

What is a good grams per hour rating for a wood stove?

Any new stove sold in the US meets the Step 2 limits of 2.0 g/h on crib wood or 2.5 g/h on cord wood, so all of them are clean by historical standards. Lower is better, and the bigger gap is against older uncertified stoves at 15 to 30 g/h.

What is the difference between crib wood and cord wood testing?

Crib wood is uniform dimensional lumber stapled together for a repeatable laboratory burn. Cord wood is ordinary split firewood, which EPA describes as a better measure of how a stove performs in homes. Compare like with like when reading two labels.

Where is the EPA certification label on a stove?

On the back of the stove. EPA's guidance is to look for it there, and the absence of a label means the stove is not certified, which matters for installation rules and sometimes for insurance.

Does a cleaner stove also mean lower fuel use?

Usually, but the label separates the two: emissions are measured in grams per hour and efficiency as a percentage. Read both, and ask on which basis the efficiency figure is quoted, because conventions differ.

Where these figures come from

1. Choosing the Right Wood-Burning Stove US Environmental Protection Agency, Burn Wise · epa.gov
2. Burn Wise US Environmental Protection Agency · epa.gov
3. Energy Efficient Home Improvement Credit Internal Revenue Service · irs.gov

Figures last checked September 2026.