Which pack size to buy
The board keeps packs under 100 kg in one table and packs of 100 kg and over in another. A tonne can be the cheapest energy on the page and still be the wrong thing to buy. Match the pack to how often you light the fire, where it will be stored, and whether a pallet lorry can reach the house.
The examples are the prices checked on 18 Oct 2026. £/kWh is the pack price only. Delivery is in its own column on the price board.
10 kg, or a couple of 10 kg bags
This is the size for trying a fuel, or for a flat with nowhere to keep a sack. It is often the highest £/kWh. That day, B&Q’s two 10 kg bags of Homefire Brazier were £0.131/kWh, and a single Wickes 10 kg bag was £0.109/kWh with £5 delivery listed as well. A merchant’s own 10 kg bag can sit much closer to their 25 kg price, so read the row rather than assuming every small bag is poor value.
20 kg and 25 kg
This is the regular bag. One person can carry it, and it is enough for a fire a few evenings a week. It is the sensible first purchase, and the size most of the bag table is built around. For which fuel belongs on which grate, see fuel grades and which appliance they suit.
A 50 kg sack
This is where the bag table gets cheaper. The cheapest bag on 18 Oct 2026 was a 50 kg sack of Supertherm from Byrn Coal Company, £34, £0.076/kWh, with free delivery and a £60 minimum order. A sack of that weight is awkward on stairs. Buy it when someone can move it and the minimum order is acceptable.
About a quarter of a tonne
Roughly 240–260 kg, often sold as 12 or 13 bags of 20 kg, or 10 bags of 25 kg. That will cover a winter of weekend fires if the fuel stays dry and the lorry can stop outside. These packs are on the pallet table. A small pallet is not automatically the cheapest row there. Compare it with the half-tonne and the tonne before you assume that “buying bigger” has already found the bottom of the price.
About half a tonne
Roughly 500 kg. This suits a stove, or an open fire used most evenings, through a heating season. You need a dry store. Smokeless briquettes keep well if they stay dry, and they are wasted if they sit in the rain.
A tonne
Roughly 1,000 kg, and usually the lowest £/kWh on the board. On 18 Oct 2026 that was Supertherm, 50 × 20 kg bags, from Bulk Coal, £550, £0.062/kWh, with delivery listed as free to most mainland postcodes. A tonne is a supply for the whole winter. It needs dry storage and access for a pallet lorry.
Once the weight is settled, the two tables stay separate on purpose. Use the bags table for anything you can carry, and the pallet table for anything that arrives on a lorry. What to buy for a first fireplace is the short version if you have only just moved in.