About the Charcoal Calculator
This charcoal calculator estimates how much charcoal to light for a cookout. Choose the cooking method — direct high heat for steaks, medium heat for chicken pieces, two-zone indirect cooking for roasts, or low-and-slow smoking — enter your grill diameter and how long you expect to cook, and it returns the number of briquettes, the weight of charcoal and how many chimney starters that is.
The starting point is the familiar 22-inch kettle: a full chimney (roughly 100 standard briquettes) for searing, about three-quarters of a chimney for medium heat, half a chimney split into two zones for indirect cooking, and a small lit batch feeding an unlit snake for smoking. Larger and smaller grills are scaled by cooking-grate area, so an 18-inch grill needs about two-thirds as much as a 22-inch one. For cooks longer than an hour, the calculator adds the briquettes you will need to top up the fire — roughly 8 per side per hour for an indirect fire.
Charcoal brands differ in size and burn rate, and wind, cold weather and opening the lid all use more fuel, so round up and keep a spare bag. Lump charcoal lights faster and burns hotter but less evenly; use about the same volume and expect to add fuel sooner.
With the default inputs, the briquettes needed is 75. Change any value above to recalculate instantly.
How to use the charcoal calculator
- 1Choose how you will cook: direct high, direct medium, indirect or low & slow.
- 2Enter your grill’s grate diameter (22 in for a standard kettle).
- 3Enter how long the food will cook.
- 4Light the initial briquettes in a chimney and add the rest as the cook goes on.
Formula and method
The initial loads are kettle-grill rules of thumb for a 22-inch grate: about 100 briquettes (one full chimney) for direct high heat, 75 for medium, 50 for a two-zone indirect fire and about 20 lit briquettes to start a low-and-slow snake. Fuel needed scales with the area of the cooking grate, so the load is multiplied by (diameter ÷ 22)².
For grilling, the first hour is covered by the initial load; after that the calculator adds about 25, 20 or 16 briquettes per hour for high, medium and indirect fires. For smoking, the snake burns roughly 13 briquettes per hour at 225–275°F from the start. Weight assumes the briquette weight you enter.
- d
- Grate diameter in inches
- h
- Total cooking time in hours
Worked examples
22-inch kettle, medium heat for an hour
Medium direct heat on a 22-inch kettle takes about 75 briquettes — three-quarters of a chimney. At 0.9 oz each that is about 4.2 lb of charcoal, and one hour needs no top-up.
22-inch kettle, indirect for 3 hours
Start with 50 briquettes split into two zones, then add 16 per hour for the two hours after the first: 32 more, for 82 in total (about 4.6 lb).
18-inch grill, low & slow for 8 hours
An 18-inch grate has (18 ÷ 22)² ≈ 67% of the area of a 22-inch kettle. Light about 13 briquettes and lay about 70 unlit in a snake (13 per hour × 8 hours × 0.67) for roughly 83 in total.
Frequently asked questions
How many briquettes are in a chimney?+
A standard large chimney starter holds about 80–100 briquettes, or roughly 5–6 lb. For a 22-inch kettle, one full chimney gives high heat for searing and about three-quarters of a chimney gives a medium fire.
How much charcoal do I need for 2 hours of grilling?+
On a 22-inch kettle, start with the usual load for your heat level (50–100 briquettes) and add about 16–25 briquettes for the second hour. For indirect cooking that is about 8 briquettes per side per hour.
How long do charcoal briquettes burn?+
A full load of briquettes stays hot enough for direct grilling for about an hour, then gradually cools. Arranged as a snake or minion fire for smoking, a 22-inch kettle full of briquettes can hold 225–275°F for 6–10 hours.
Is lump charcoal or briquettes better?+
Lump charcoal lights faster, burns hotter and leaves less ash, which suits searing. Briquettes are uniform, cheaper and burn at a steadier temperature for longer, which suits long indirect cooks and smoking.
How do I know when the charcoal is ready?+
Coals are ready when they are mostly covered in light grey ash, usually 15–20 minutes after lighting a chimney. Spreading them earlier causes uneven heat and acrid smoke.