Mulch calculator / Measure from a scale-ready image
Mulch Photo Area Calculator
Trace a bed only when the image has a usable ground scale. Calibrate a visible reference, mark the mulched boundary, then turn the traced area into a material estimate.
01 / Check the image
Choose a scale-ready source
A perspective photo cannot be reliably measured with one scale. Select a suitable source first.
Local only: the chosen image is drawn in this browser tab. It is not uploaded or saved by this tool.
Up to 12 MB. Large images are reduced in memory for display. Use only a map image with uniform scale, a measured plan, or a near-overhead view of a level bed.
02 / Set scale
Mark a known ground length
Choose “Set scale,” then tap the two ends of a length you know. It must lie on the same flat plane as the bed. Resetting scale clears outlines drawn with the old scale.
No scale set. Choose two endpoints on the image.
03 / Trace the bed
Draw only the ground to mulch
Tap boundary points around one bed, then finish the outline. Add separate exclusion shapes for trunks, paving, or other unmulched islands. Don't trace overlapping ground twice.
Select a suitable image and set the scale before tracing. Keyboard: focus the image, use arrow keys to move the crosshair, then press Enter to add a point.
Illustrative worked answer
42 sq ft to cover
At a user-chosen 2 in depth, that is 7 cu ft or about 0.26 cu yd. With a user-entered 2 cu ft bag size, round up to 4 bags.
How the estimate is made
A scale line is required; a picture alone is not a measurement
The tool finds the pixel area inside your traced bed outline, subtracts any exclusion shapes, and converts pixels to square feet using the reference length you enter. It then multiplies area by your selected depth in feet. Cubic feet are divided by 27 for cubic yards; whole bags are rounded up from the bag volume you enter.
Area (sq ft) ≈ traced image area (px²) × [known ground length (ft) ÷ image length (px)]²
Volume (cu ft) = area (sq ft) × depth (in) ÷ 12
Cubic yards = cubic feet ÷ 27
The USGS explains that orthophotos remove displacement from camera tilt and terrain relief, which is why this tool separates rectified overhead images from ordinary perspective photos. A near-overhead phone image is still only a rough estimate. The Iowa State University Extension mulch guide supports the area × depth volume relationship and cubic-yard conversion.
This worksheet does not recommend a depth, estimate from a photo automatically, decide whether a bed is safe for a particular material, or account for waste, settlement, delivery terms, or supplier tolerances. Trace one bed at a time; for several measured zones, use the mulch order-by-zone calculator. For a hand-drawn scaled grid, use the measured-grid area calculator. For direct field measurements, use the irregular-width calculator.
Questions about measuring mulch area from an image
Can I measure a bed from any phone photo?
No. An angled or perspective photo does not have one reliable scale across the ground. Use an orthorectified overhead image, a measured plan, or a near-overhead image of level ground for a rough estimate. A known length must be visible on the same plane as the bed.
What does the image tool calculate?
It converts the manually traced pixel outline to an area using your known reference length, subtracts any exclusion zones you trace, then multiplies by the depth you enter. The result is an estimate, not a site survey or guaranteed order quantity.
Is my image uploaded or saved?
No. The selected image is opened and drawn in this browser tab only. It is not sent to a server or stored by this tool. Use Clear image when you are finished.
Can I leave out trees, pavers, or other areas?
Yes. Trace each unmulched island as an exclusion inside the bed outline. Exclusion shapes must stay inside the bed and cannot overlap. Do not trace the same mulched ground twice.