Staying warm in the colder months requires planning, and knowing how much firewood you need is essential.
Factors like fire type, room size, and frequency of use can all influence how much you’ll burn.
At Stewart Timber, we offer high-quality, sustainably sourced firewood, perfect for any heating setup, from log burners to outdoor firepits.
Read on for simple steps to estimate your firewood needs.
How to Calculate Your Firewood Needs
Estimating your firewood needs starts with three key factors: the type of fire, the size of your space, and how often you light it.
Staying warm in the colder months requires planning, and knowing how much firewood you need is essential.
Factors like fire type, room size, and frequency of use can all influence how much you’ll burn.
At Stewart Timber, we offer high-quality, sustainably sourced firewood, perfect for any heating setup, from log burners to outdoor firepits.
Read on for simple steps to estimate your firewood needs.

How to Calculate Your Firewood Needs
Estimating your firewood needs starts with three key factors: the type of fire, the size of your space, and how often you light it.
1. Fire Type and Efficiency
- Log Burners: Use 3–4 logs per hour, depending on size and efficiency.
- Open Fires: Less efficient, burning 5–7 logs per hour.
- Outdoor Firepits: Generally use 2–3 logs per hour for casual use.
2. Room Size and Insulation
- Small Rooms (10–15m²): Need about 2–3 logs per hour.
- Medium Rooms (15–25m²): Require 3–4 logs per hour.
- Large Rooms (25m²+): May burn through 5+ logs per hour, especially in poorly insulated spaces.
3. Usage Frequency and Season
- Occasional Use: Lighting a fire twice a week for 3 hours in a medium room would use 18–24 logs per week.
- Daily Use: A daily 4-hour fire in a large room could consume around 140 logs per week.
- Seasonal Use: For a 12-week winter, expect to burn 1,680 logs for daily fires or 144–288 logs for occasional use.
Example Calculations
If you light your log burner daily for 5 hours in a large room:
5 logs/hour × 5 hours × 7 days = 175 logs per week.
If you light your fire three times a week for 4 hours in a medium-sized room: 3 logs/hour × 4 hours × 3 days = 36 logs per week.
Once you’re ready to stock up, Stewart Timber offers top-quality, sustainably sourced firewood for any setup.
How Long Does a 20kg Bag of Firewood Last?
The lifespan of a 20kg bag of firewood depends on the type of fire and how often you use it. Here’s a quick breakdown:
- Occasional Fires: If you light your fire once or twice a week for 3–4 hours, a 20kg bag should last around 1–2 weeks.
- Daily Use: For a daily fire of 4 hours, you’ll likely burn through a 20kg bag in 3–4 days.
- High-Intensity Use: For longer or hotter fires (e.g., open fires or poorly insulated spaces), a 20kg bag may only last 1–2 days.
Example Calculation
- If your fire burns 3 logs per hour and each log weighs about 1kg, a 20kg bag will provide 20 logs, enough for approximately 6–7 hours of burn time.
As a rule, we recommend focusing on the volume of a bag of wood rather than the weight. This is because extra weight can be made up of water which is useless (and harmful!) for your fire. At Stewart Timber, we sell firewood by volume so you only get good quality wood that will burn efficiently and for longer.

Proper Firewood Storage
For firewood to burn efficiently, proper storage is essential. You can ensure the longevity and quality of your firewood by storing it in the right conditions.
Check out our helpful blog posts on How to Stack Logs in a Log Store Safely & Correctly and How to Store Firewood Properly for expert tips on keeping your logs in top condition. If you’re storing firewood outdoors, our How to Safely Store Your Firewood Outdoors blog is also a must-read.
Why Buy Your Firewood from Stewart Timber?
When it comes to sourcing firewood, Stewart Timber stands out as a trusted provider of high-quality, sustainably sourced wood. Here’s why customers keep coming back:
- Kiln-Dried Hardwood: Our kiln-dried logs have a moisture content of less than 20%, ensuring efficient, long-lasting burns with minimal smoke. All our firewood is Woodsure accredited, meaning it meets stringent quality standards for safe burning.
- Flexible Options: Choose from single bags for occasional use or bulk bags for a full winter’s supply. All firewood is sold by volume, so you pay only for usable wood.
- Sustainability: We prioritise environmentally friendly practices, sourcing all firewood locally and from FSC-certified suppliers.
- Fast, Convenient Delivery: Enjoy free delivery within 30 miles of Glasgow, making it easier than ever to stay stocked up for the season.
Conclusion
Estimating how much firewood you need is essential for keeping your home warm all season. By considering factors like fire type, room size, and frequency of use, you can better plan your firewood purchases.
For expert advice and high-quality firewood, contact Stewart Timber today!
Browse our range of firewood here and stay warm this winter!