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Tools

Calculators for buyers and heating installers

Simple calculations using your own figures: energy units, the effect of moisture and the amount of ash over a season. The results are calculated values — they do not replace fuel testing.

Energy unit converter

1 kWh = 3.6 MJ. Divide the value in MJ/kg by 3.6 to get kWh/kg.

MJ/kg
kWh/kg

How moisture affects calorific value

Enter the calorific value on a dry basis (from the laboratory report) and the moisture content. The calculator shows the value as received — the energy your boiler can actually use.

MJ/kg

Example value — replace it with data from the report.

%

Example value — replace it with data from the report.

As received

17.28 MJ/kg

As received

4.80 kWh/kg

Difference from dry basis

−9.0 %

141516171819200%5%10%15%MJ/kg (as received) · X axis: moisture content

Formula: Q_ar = Q_d × (100 − M) / 100 − 0.02443 × M, where 0.02443 MJ/kg is the heat of vaporisation of water per percentage point of moisture (ISO 18125). The result is a calculation and does not replace a measurement.

Energy and ash over a heating season

Shows what the figures on a product sheet mean in practice for your annual consumption.

MJ/kg

From the product sheet or test report.

%

From the product sheet or test report.

t

An estimate for your building.

Energy in 1 tonne
4,722 kWh
Ash per season
25 kg
15 kg bags per season
334 bags

Ash [kg] = ash content [%] × 10 × consumption [t]. Energy here means the chemical energy in the fuel — the heat delivered to your heating system is lower by the amount of the boiler’s losses.

Sources and references

Full list of sources and editorial policy
  1. [1]

    ENplus® ST 1001:2022 — ENplus® wood pellets – Requirements for companies (2nd edition) (opens in a new tab)

    European Pellet Council / Bioenergy Europe, DEPIapproved 18.06.2025, in force from 01.01.2026Certification schemeaccessed: 11/09/2026

    Annex A, Table 4 (threshold values) and Table 5 (raw material). The limits are the same as in the first edition; the method for determining fines has changed to ISO 5370.

  2. [17]

    ISO 18125:2017 Solid biofuels — Determination of calorific value (opens in a new tab)

    ISO / TC 238Standard paid documentaccessed: 11/09/2026

This content is an editorial summary based on the documents cited. Always confirm threshold values in the current edition of the standard or certification scheme document.

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