As a guide, allow 200g of roast potatoes per adult (normal appetite).
Quick calculator
For roast potatoes, allow about 200g of raw potato per adult — roughly 3–4 roasties each — for a normal appetite as part of a full roast dinner. People tend to go back for seconds, so it’s worth erring on the generous side.
How much to buy
- Light eater: ~150g each
- Normal: ~200g each
- Hungry / potato lovers: ~300g each
- Child: ~100g each
So for a family of four adults, buy around 800g–1kg of potatoes, or a bit more if roasties are the star of the meal.
Raw vs cooked
Potatoes lose a little weight as they roast (some moisture cooks off), so 200g raw gives a satisfying portion of finished roasties. Buy a floury variety like Maris Piper or King Edward for the crispiest results.
How much roast potatoes for 2, 4, 6, 8 and 10 people
| People | Amount (g raw potato) | Cooked weight |
|---|---|---|
| 2 | 400g | 320g |
| 4 | 800g | 640g |
| 6 | 1200g | 960g |
| 8 | 1600g | 1280g |
| 10 | 2000g | 1600g |
Portion sizes
- Light: 150g per person
- Normal: 200g per person
- Hungry: 300g per person
- Child: 100g per child
How this is worked out
Roast potatoes are a favourite, so people eat more of them than everyday potatoes. Around 200g of raw potato per adult (roughly 3–4 good roasties) suits a normal appetite as part of a roast; scale up for a potato-loving crowd.