An interactive, browser-based calculator that determines the urban block size that maximizes pedestrian accessibility to all surrounding parcels within a given walkshed distance. Companion tool for:
Sevtsuk, A. (2026). Are Smaller Blocks More Walkable? Testing the Nonlinear Relationship Between Urban Block Size and Pedestrian Travel.
Given parcel and street dimensions, this tool computes which block size (measured in plots per frontage) maximizes pedestrian accessibility using a Hansen gravity-based model. It tests a range of block sizes and identifies the one that best balances route efficiency against street-crossing costs.
The calculator also produces:
- An interactive gravity curve showing mean accessibility across all tested block sizes
- A block grid visualization depicting the optimal layout with streets, parcels, and entrance points
The conventional planning wisdom holds that smaller blocks are always better for walkability. This tool demonstrates why that isn't necessarily true: while shorter blocks create more intersections and route choices, they also introduce more frequent street crossings and reduce parcel density within a fixed walking radius. The result is a nonlinear, parabolic relationship where both excessively small and excessively large blocks reduce accessibility.
The optimal block size depends on local conditions — parcel frontage, parcel depth, street widths, and willingness to walk.
| Parameter | Description | Default |
|---|---|---|
| Plot Frontage | Width of each parcel along the street (m) | 15 |
| Plot Depth | Depth of each parcel perpendicular to street (m) | 30 |
| Street Width X | Width of horizontal streets (m) | 15 |
| Street Width Y | Width of vertical streets (m) | 15 |
| Beta | Distance decay (willingness to walk) | 0.005 |
| Search Radius | Maximum walking distance (m) | 1000 |
- Enter your parcel and street dimensions
- Optionally adjust beta and search radius under "Advanced Parameters"
- Click Compute Optimal Block Size
- Explore the Block Grid and Gravity Curve tabs
This is a single-file HTML application with no build step or dependencies. Simply open index.html in any modern browser.
- Sevtsuk, A., Kalvo, R., & Ekmekci, O. (2016). Pedestrian accessibility in grid layouts: The role of block, plot and street dimensions. Urban Morphology, 20(2). doi:10.51347/jum.v20i2.4056
MIT