How Much Does an Oak Log Weigh? (Unseasoned vs Seasoned vs Kiln-Dried)

Oak is one of the most popular firewood logs in the UK thanks to its slow burn, high heat output, and long-lasting embers. But if you’re wondering “How much does an oak log weigh?” the answer depends on several key factors, including how the log has been prepared and dried.

In this guide, we’ll cover the typical weight of a 25cm cut oak logs, explain the differences between unseasoned, seasoned and kiln-dried oak, and highlight the reasons why the weight varies.

Why Oak Logs Vary in Weight

No two oak logs are exactly the same. Several factors influence their weight:

• Moisture content – Freshly cut (or “green”) oak logs hold a high level of water, making them significantly heavier than dried logs.
• Log size and diameter – A 25cm length is standard for logs for wood burners, but the thickness of the log will greatly affect weight.
• Drying method – Whether the log is left to air dry naturally (seasoned) or dried in a kiln changes the final weight.

Approximate Weights of a 25cm Oak Log

Here’s a guide to the weight of an average 25cm long oak log, cut to a typical stove-ready thickness (around 10–15cm diameter).

1. Unseasoned (Freshly Cut) Oak Log

• Weight: Around 3.5–5kg per log
• Moisture content: Typically 40–60%
• Why so heavy? Oak is a very dense hardwood. When freshly cut, it’s saturated with water, making the logs bulky and heavy. Burning them at this stage is inefficient and produces excess smoke and creosote.

2. Seasoned Oak Log

• Weight: Around 2.5–3.5kg per log
• Moisture content: 20–25% (after being air-dried outdoors for 12–24 months)
• Why lighter? Over time, water naturally evaporates, reducing the weight. Seasoned oak is suitable for burning if it meets the Ready to Burn standard (<20% moisture).

3. Kiln-Dried Oak Log

• Weight: Around 2–3kg per log
• Moisture content: Below 20% (often around 10–15%)
• Why the lightest? Kiln dried logs are dried using controlled heat and airflow, which accelerates the evaporation process. This results in a consistently drier, lighter log that burns hotter, more cleanly, and more efficiently than seasoned logs.

Why Moisture Content Matters

The moisture content of a log is the single biggest factor in its weight. Water is heavy, so the more moisture inside the log, the heavier it will be. For example, an unseasoned oak log can weigh almost double that of a kiln-dried oak log of the same size.

This also affects how well the log burns:

• Unseasoned logs – smoky, difficult to light, waste energy evaporating water.
• Seasoned logs – better, but moisture can be inconsistent.
• Kiln-dried logs – lightest, driest, and best performing for log burners and multi-fuel stoves.

Final Thoughts

So, how much does an oak log weigh? A standard 25cm oak log typically weighs:

• Unseasoned: 3.5–5kg
• Seasoned: 2.5–3.5kg
• Kiln-dried: 2–3kg

The exact weight will vary depending on thickness, moisture level, and drying method. As a rule of thumb, the drier the log, the lighter it will be — and the better it will burn.

Tip: If you want the most consistent results for your wood burner, kiln dried oak logs are the best option. They’re lighter to handle, give you more heat per log, and provide a cleaner, more efficient burn.