Free Macro Depth of Field Calculator

Depth of field at macro magnifications is the narrow band of sharpness around the focus point — so thin that effective aperture and stacking step size matter as much as the f-number. At macro distances the normal DoF formulas break down — magnification takes over. This calculator uses the magnification-based approximation, reports your effective aperture, and gives you the exact focus-stacking step size.

Your setup

Camera

Magnification (reproduction ratio)

1:1 = subject is life-size on the sensor · most macro lenses reach 1:1, extension tubes/reversing rings go beyond

Set aperture (f/)

Macro lenses report the set f-stop; the effective aperture is wider (more light loss) as magnification rises

Result

Depth of field

—

at this magnification

Effective aperture

—

what the sensor sees

Stacking step

—

move focus this far per shot

🔬 Reading: at your total DoF is — thinner than paper. To photograph a whole insect, shoot a stack: move focus between frames (overlap 20–30% for safety), then merge in Helicon Focus or Photoshop.

Why macro DoF is different

At 1:1 magnification, depth of field is roughly DoF ≈ 2·N·c·(m+1)/m² — it scales with the square of magnification, which is why 2:1 has about a quarter of the DoF of 1:1 at the same f-stop. Two practical consequences:

Stopping down barely helps. f/16 at 1:1 gives ~1.9 mm of DoF on full frame — and diffraction (plus effective-aperture light loss) is already visible.
Effective aperture widens. At 1:1 the effective aperture is 2 stops slower than set: f/8 set = f/16 effective. Your meter and exposure need the compensation, which is why macro images look underexposed at high magnification.

Related tools & guides

Depth of Field Calculator

The standard near/far calculator for non-macro work.

Open →

Depth of Field for Macro

Stacking workflow, lighting, and lens choices.

Read →

Exposure Equivalence

Recompute exposure when effective aperture kicks in.

Open →

Macro DoF FAQ

Why is my sharp area so thin even at f/16?

Because DoF falls with the square of magnification. At 2:1, f/16 gives under 1 mm. Diffraction also erodes sharpness beyond ~f/11 effective — which is exactly why macro photographers focus-stack instead of stopping down.

What does effective aperture mean for exposure?

The effective aperture is N × (1 + m). At 1:1 it's two stops narrower than set, so your camera's through-the-lens metering compensates automatically — but manual flash calculations must add those stops or your macro shots come out dark.

How do I choose a stacking step size?

Move focus by roughly 80% of the DoF per frame (the calculator's step uses this with safety overlap). Too big → gaps that even software can't stitch; too small → hundreds of redundant frames.