How Much Do Pellet Boilers Consume Per Month?

Updated: 14 August 2026 · Timo Pellets, wood pellet producer, Certeju de Sus, Romania · Citește în română

In short: a pellet boiler consumes on average 6–8 kg of pellets per square metre per month in a well-insulated home during peak winter. For a 100 sqm house that means roughly 600–900 kg per month (40–60 bags of 15 kg) and 3–4 tonnes over a full heating season. Consumption rises by 30–50% in a poorly insulated building.

This is the question buyers ask us most often before their first order, and rightly so: the answer determines the entire winter budget. Below are concrete figures, a table by house size, and the calculation method you can apply to your own home.

Consumption table by house size

The values below assume a well-insulated home, during the coldest months, with an indoor temperature of 21–22 °C and quality pellets (calorific value above 4.8 kWh/kg).

Floor area	Boiler output	Daily use	Monthly use	Per season
80 sqm	15–20 kW	15–22 kg	450–650 kg	2.5–3 t
100 sqm	20–25 kW	20–30 kg	600–900 kg	3–4 t
150 sqm	25–30 kW	25–35 kg	750–1,100 kg	4.5–6 t
200 sqm	30–40 kW	35–50 kg	1,000–1,500 kg	6–8 t
250 sqm	40–50 kW	45–65 kg	1,300–1,900 kg	8–10 t

For a poorly insulated building, multiply these figures by 1.3–1.5. For a high-performance new build, subtract 20–25%.

How to calculate it yourself, in three steps

Step 1: estimate the heat demand

The rule of thumb used by installers: 0.08–0.12 kW per square metre for an insulated house, and 0.12–0.15 kW/sqm for an uninsulated one. A 120 sqm insulated house needs roughly 12 kW.

Step 2: convert to kilograms

One kilogram of quality pellets yields about 4.8–5 kWh, and a modern boiler runs at 88–93% efficiency. In practice you get around 4.3–4.5 kWh of usable heat per kilogram.

Formula: daily consumption (kg) = heat demand (kW) × effective running hours ÷ 4.4

Example: a 120 sqm house needing 12 kW, with the boiler running at full load for around 8 hours on a freezing day: 12 × 8 ÷ 4.4 = about 22 kg per day.

Step 3: scale to the season

A heating season lasts 180–210 days, but only 60–80 of those are peak-consumption days. The seasonal average is usually 55–65% of peak daily consumption.

What drives consumption most

Factor	Impact on consumption
Wall and roof insulation	Up to 35% — the single biggest factor
Pellet quality (moisture, ash, calorific value)	20–30% for the same heat delivered
Climate zone	Up to 100% between mountain and lowland regions
Boiler efficiency and age	10–15% between a modern unit (93%) and an old one (80%)
Indoor temperature setting	About 6–7% per additional degree
Windows and air-tightness	10–20%

The mistake that costs the most

Many buyers choose pellets purely on price per tonne. That comparison is misleading, because two bags do not deliver the same heat. Pellets with 12–15% moisture and 1.5% ash may look 15% cheaper, but you burn 25% more to reach the same indoor temperature — so you pay more overall, plus more frequent cleaning and faster boiler wear.

The correct comparison is cost per usable kWh: divide the price per kilogram by the declared calorific value. Our hardwood pellets deliver ≥ 4.8 kWh/kg with ash ≤ 0.7%, precisely so that this ratio works in your favour.

Frequently asked questions

How much do pellets cost to heat a 100 sqm house per month?

In a well-insulated 100 sqm house, monthly consumption in peak season is roughly 600–900 kg of pellets, or 40–60 bags of 15 kg. At typical European prices this translates to a few hundred euros per month during the coldest period.

How many kg of pellets per day does a house use?

On a cold winter day, a well-insulated 100 sqm house burns around 20–30 kg of pellets, or about two 15 kg bags. In transition months this drops to 8–15 kg per day.

How many tonnes of pellets do I need for a whole winter?

For a full heating season, a well-insulated 100 sqm house needs approximately 3–4 tonnes. A 150 sqm house needs 4.5–6 tonnes, and a poorly insulated 200 sqm house can exceed 8 tonnes.

How can I reduce pellet consumption?

Insulating walls and roof, fitting efficient windows, using a programmable thermostat, cleaning the boiler regularly, and choosing pellets with moisture below 10% and ash below 0.7%. Poor quality pellets can increase consumption by 20–30% for the same heat output.

Premium pellets, direct from the producer

Timo Pellets produces hardwood pellets (beech, oak, hornbeam, ash, black locust) in Certeju de Sus, Hunedoara County, Romania. Delivery across Romania and internationally.

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