Safety notice

Input stays in this browser and is not sent to a server.

Do not trust a single number. Check footing, wind, crown weight, and the actual fall path first.
Keep clear of roads, drop-offs, dead branches, and power lines before the cut starts.
If the escape side looks unsafe, choose another direction and re-evaluate on site.

Forestry Tools

Tree Felling Safety Zone Calculator

Q: "Does it work without a connection?"

"Yes. All calculations run in the browser, so it remains useful even when you are offline."

Q: "Can I use this for legal or regulatory judgment?"

"No. It is a field aid only. Follow site rules, local law, and the supervisor's instruction."

Q: "How does auto direction work?"

"Auto mode compares slope and nearby obstacles, then chooses the more conservative of the uphill, cross-slope, and downhill options. It does not replace site judgment."

Q: "What should I enter as obstacles?"

"Enter roads, structures, standing trees, snags, or power lines that could affect the escape path."

Q: "What is included in the share URL?"

"Tree height, slope, retreat direction, obstacle rows, and lightweight settings are encoded in the URL."

Q: "Can I mix meters and feet?"

"Yes, if the units are explicit. Keep a consistent notation whenever possible."

Enter tree height, slope, retreat direction, and nearby obstacles to estimate retreat distance and exclusion radius.

It is designed as a conservative field aid, so it stays useful offline and does not try to make a legal determination.

45° escape-angle guide

Uses two tree lengths as the base

Obstacle-aware

Offline friendly

How to use

1 Enter tree height and slope. Slope can be entered as angle, percent grade, or a 1:n ratio.
2 Set the retreat direction to Auto, Uphill, Cross-slope, or Downhill if you need to override the suggestion.
3 Add adjacent obstacles such as roads, structures, standing trees, snags, or power lines.
4 Review the retreat distance and exclusion radius, then use the result only as a support aid.

Sample

24 m / 12° / auto / snag 6 m

Input

Tree height 24 m / slope 12° / retreat direction auto / obstacle: snag 6 m

Output

Uphill is selected. Retreat distance is about 12.7 m, and exclusion radius is about 50.6 m.

80 ft / 18% / uphill / road 10 ft

Input

Tree height 80 ft / slope 18% / retreat direction uphill / obstacle: road 10 ft

Output

Uphill is selected. Retreat distance is about 42 ft, and exclusion radius is about 167 ft.

FAQ

Does it work without a connection?

Yes. All calculations run in the browser, so it remains useful even when you are offline.

Can I use this for legal or regulatory judgment?

No. It is a field aid only. Follow site rules, local law, and the supervisor's instruction.

How does auto direction work?

Auto mode compares slope and nearby obstacles, then chooses the more conservative of the uphill, cross-slope, and downhill options. It does not replace site judgment.

What should I enter as obstacles?

Enter roads, structures, standing trees, snags, or power lines that could affect the escape path.

What is included in the share URL?

Tree height, slope, retreat direction, obstacle rows, and lightweight settings are encoded in the URL.

Can I mix meters and feet?

Yes, if the units are explicit. Keep a consistent notation whenever possible.

Glossary

Retreat distance

The distance you should move away from the stump once the cut is underway.

Exclusion radius

A conservative radius around the tree and its fall path where people should stay out.

Retreat direction

The direction used for escape, such as uphill, cross-slope, or downhill.

Slope buffer

Extra distance added to the retreat estimate because of slope.

Obstacle buffer

Extra distance added because nearby obstacles may block the retreat route.

Field judgment

The site-specific decision made by the crew after checking the actual conditions on the ground.

Calculation formulas

Reference angle = 45°
Effective length = tree height + slope buffer + obstacle buffer
Retreat distance guide = max(minimum retreat distance, effective length × 0.5)
Exclusion radius guide = max(2 × tree height, 2 × effective length)
Slope buffer = tree height × grade × direction factor
Grade = tan(slope angle)

Notice

This tool is not a legal determination. Follow site rules, local law, and the supervisor's instruction first.
Do not rely on the numeric result alone when there are roads, power lines, drop-offs, or other serious hazards nearby.
On steep slopes, confirm footing and escape routes before you move.
It works offline, but printing and location-related features still depend on the device and browser.
Share URLs include your inputs. Do not put private site names into a link you plan to publish.