The official companion guide arrived on time for me so I thought I'd share one of the most sought after parts for people who can't access the guide.
Star Rating Values
The star rating values are split into two separate categories: Development and Scenery. In order to increase your star rating, you must meet certain thresholds in both of these categories
| Development | Scenery | Rating |
|---|
| Less than 80 | Less than 200 | 1 Star |
| 80 to 159 | 200 to 269 | 2 Stars |
| 160 to 399 | 270 to 349 | 3 Stars |
| 400 to 664 | 350 to 449 | 4 Stars |
| 665+ | 450+ | 5 Stars |
Island Scenery
| Plantlife | Added Points |
|---|
| Trees (including bamboo) | +1 point for each fully grown tree up to 190 points |
| Flower Sprout | +0.5 Points |
| Flower Stem | +0.7 Points |
| Flower Bud | +0.7 Points |
| Adult Flower | +1 Point |
Furniture placed is graded on an 8x8 tile basis known as a block.
| DIY Furniture within a block | Added Points |
|---|
| For each unique piece of DIY furniture that is 3x1, 3x2 or 3x3 tile size | +1 point |
| 4 or less different types of furniture | The number of furniture placed x 0.25 points |
| 5-10 different types of furniture | The number of furniture placed x 0.25 points |
| 10 or more different types of furniture | The number of furniture placed x 0.25 and the number of types x 0.75 |
Island Development
| Condition | Added Points |
|---|
| Museum built | +15 |
| Nook's Cranny has been upgraded | +15 |
| Able Sisters is built | +15 |
| Bridge | + (Number of Bridges) x 15 |
| Incline | + (Number of Inclines) x 15 |
Non-DIY Furniture is still graded on the 8x8 tile basis
| Furniture within a block | Added Points |
|---|
| Less than 5 unique types of furniture | Number of placed furniture x 1 |
| 5 to 10 unique types of furniture placed | Number of placed furniture x 0.5 + The number of types x 0.5 |
| 10+ unique types of furniture | Number of placed furniture x 0.5 + The number of types x 0.75 |
Furniture Type and Bonuses
| Bonus | Added Points |
|---|
| The placed furniture is recommended for the outdoors | Number of outdoor furniture x 0.5 additional points |
| The placed furniture costs 2000-20,000 bells | Number of applicable furniture x 1 |
| The placed furniture costs over 20,000 bells | Number of applicable furniture x 2 |
| Placed fences | Number of fences x 0.2 |
Negative Conditions
Clutter
- Clutter is gauged in the same 8x8 tile divisions as furniture
- If 45/64 or more tiles are covered in the block, the block is considered cluttered
- Buildings, bridges, buried items, rocks, cliffs, rivers and inclines will not count towards this
Littering
- If there are more than 15 small items dropped on the ground, your island will be deemed messy
- Naturally occurring items such as tree branches, stones and star fragments do not count
If either of these conditions are met, your town can not achieve five stars.
PS: Sorry for the awful editing