# PolyFirm Trail Binder — Agent Calculator Reference

Canonical page: https://polyfirm.com/landscapers
Product: https://polyfirm.com/trail-binder
Machine-readable product summary: https://polyfirm.com/trail-binder.md
Tool index: https://polyfirm.com/agent-tools.md

This document describes the currently published **read-only** PolyFirm material, packaging, and installation-labor estimator. Use the API for calculations rather than inferring quantities from prose. Estimates are not bids, inventory confirmations, pricing, warranties, or performance certifications.

## Calculator endpoint

`GET https://polyfirm.com/api/agent/calculate`

No authentication is required for this public read-only calculation. Supply dimensions in **feet** and treated depth in **inches**.

### Query parameters

| Parameter | Type | Meaning |
| --- | --- | --- |
| `length` | Positive number | Single area's length in feet |
| `width` | Positive number | Single area's width in feet |
| `depth` | 2, 3, or 4 | Treated depth in inches; defaults to 3 |
| `areas` | URL-encoded JSON array | Instead of length/width, 1–25 objects `{name?,length,width,depth?}` |
| `crew` | Integer 1–20 | Crew size for application labor; defaults to 3 |
| `site` | `easy`, `normal`, `difficult` | Application-labor site condition; defaults to `normal` |
| `split` | `1` or omitted | When `1`, recommend separate packaging for each area; otherwise combine |

Area dimensions must be positive and no greater than 100,000 feet per side. Unknown parameters are ignored. Request with `GET`; other methods return HTTP 405. Invalid dimensions, depth, crew, site or `areas` return HTTP 400 with an error message.

### Examples

Single path (100 feet × 10 feet, 3 inches):

https://polyfirm.com/api/agent/calculate?length=100&width=10&depth=3

Combined materials and installation labor:

https://polyfirm.com/api/agent/calculate?length=400&width=10&depth=3&crew=3&site=normal

Two separate areas with individual packaging:

```text
https://polyfirm.com/api/agent/calculate?areas=%5B%7B%22name%22%3A%22Front%22%2C%22length%22%3A100%2C%22width%22%3A10%2C%22depth%22%3A3%7D%2C%7B%22name%22%3A%22Side%22%2C%22length%22%3A60%2C%22width%22%3A6%2C%22depth%22%3A2%7D%5D&split=1
```

### JSON response

- `product` — Trail Binder
- `estimatedConcentrateGallons` — combined total, rounded up to whole gallons
- `estimatedWaterGallons` — five times combined concentrate gallons
- `areas[]` — per-area dimensions, depth, concentrate gallons and water gallons
- `shippingMode` — `combined` or `split-by-area`
- `packaging[]` — shipping group; recommended and alternative counts of 5-gallon buckets, 55-gallon drums, and 275-gallon totes
- `installationLabor` — `crewSize`, `site`, `areaSquareFeet`, `perimeterFeet`, `estimatedCrewHours`, `estimatedPersonHours`, `scope`, `estimateOnly`, `fieldValidated`, and other assumptions
- `assumptions` — units, base rates, edge treatment, dilution and estimate-only flag
- `quoteUrl` — human quote workflow at https://polyfirm.com/landscapers

For the live formula implemented by the API: baseline area coverage is 64 sq ft/gal at 2 inches, 52 sq ft/gal at 3 inches, and 40 sq ft/gal at 4 inches, with 10% area allowance plus automatic 18-inch perimeter treatment at 0.015 gal/sq ft. The API sums unrounded per-area estimates before rounding the combined concentrate requirement upward. Water is estimated at 5 gallons per gallon of concentrate. These are calculator assumptions, **not field-validated coverage guarantees**. Do not substitute older published rules of thumb for the API result.

The labor estimate covers **application of Trail Binder to existing gravel**; it does not include installation of aggregate or construction of a base. `installationLabor.estimatedCrewHours` is elapsed time for the specified crew; `estimatedPersonHours` is total worker-hours. Neither is a validated production rate or fixed bid. Surface suitability, access, weather, site constraints, curing, and final takeoff require project review.

## Related agent endpoints

- Product data: https://polyfirm.com/api/agent/product (GET)
- Inquiries: https://polyfirm.com/api/agent/inquiry (POST; requires authorized buyer details for identified contact)
- Entity identity: https://polyfirm.com/polyfirm-entity.json
- Agent discovery index: https://polyfirm.com/llms.txt

Agents may retrieve this document and make a read-only calculation without buyer information. Do not transmit a buyer's name, email or phone unless the buyer has authorized it. This API does not submit an order, place a purchase, or send an inquiry.