Depth of Field Calculator

Depth of field is the range of distances in front of and behind your focus point that look acceptably sharp. It's controlled by four things: focal length, aperture (f-number), focus distance and the circle of confusion — the largest blur spot that still reads as a sharp point. This calculator uses the standard thin-lens equations found in most depth-of-field tables.

The formulas

With focal length f, f-number N, circle of confusion c and focus distance s (all in the same units):

• Hyperfocal distance H = f² ÷ (N × c) + f
• Near limit = s × (H − f) ÷ (H + s − 2f)
• Far limit = s × (H − f) ÷ (H − s), or infinity when s is at or beyond H
• Total depth of field = far limit − near limit

Worked examples

Stopping down from f/2.8 to f/8 (with a wider lens) turns a few tens of centimetres of sharpness into several metres — which is why interviews at f/2 and landscapes at f/8 look so different.

Sensor presets and circle of confusion

Each preset's circle of confusion is its image diagonal ÷ 1500, a common modern convention. Traditional tables vary: many quote 0.030 mm for full frame, and motion-picture tables often use 0.025 mm (one thousandth of an inch) for 35 mm cine. Enter your own value in the optional field if you work to a different standard.

Sensor sizes are nominal. Real cameras differ slightly, and many crop the sensor in certain video modes — if yours does, choose the format closest to the area actually recorded, or enter a custom circle of confusion.

Assumptions and limitations

• “Acceptably sharp” is a judgement, not a physical boundary. The same shot can look sharp on a phone and soft on a cinema screen — the circle of confusion encodes that viewing assumption.
• The thin-lens model ignores lens design details (pupil magnification, focus breathing, field curvature) and becomes unreliable at macro and very close focus distances; the calculator warns you in that range.
• Focus distance is treated as measured to the lens. Lens distance scales and tape measures usually run from the sensor plane (the focal-plane mark), which only makes a noticeable difference at close range.
• Diffraction softening at small apertures and anamorphic lens behaviour are not modelled.
• Results are approximations to guide shot planning and focus pulling — always check focus on a calibrated monitor. For background blur and creative choices, see our guide to the bokeh effect.