Depth of Field Calculator

Depth of field is the zone in front of and behind the focus point that still looks acceptably sharp. Portrait photographers want it thin so the background melts away; landscape photographers want it deep enough to cover everything from the foreground rocks to the mountains. This calculator shows where that zone begins and ends for your camera, lens, aperture and focus distance.

What you enter

Choose the sensor size, from full frame and APS-C to Micro Four Thirds, 1-inch, medium format, classic film formats and a typical phone camera. Enter the real focal length, the aperture and the distance to the subject in metres or feet. The results update as you type.

The circle of confusion

“Acceptably sharp” needs a definition. The calculator uses the common standard: a blur spot smaller than the sensor diagonal divided by 1442, which is 0.030 mm on full frame, looks sharp in a typical print viewed at a normal distance. Smaller sensors get a proportionally smaller value, because their images are enlarged more. If you print very large or inspect at 100 percent on screen, real sharpness is less forgiving than the numbers.

A portrait example

A 50 mm lens at f/2.8 on full frame, focused at 3 metres, keeps sharp from about 2.73 to 3.33 metres, a zone of 60 centimetres. With an 85 mm at f/1.8 focused at 2 metres, the zone shrinks to about 6 centimetres, from 1.97 to 2.03 metres: enough for the eyes, not for the tip of the nose and the ears at once. That is why focusing on the nearer eye matters at wide apertures.

Hyperfocal distance for landscapes

The hyperfocal distance is the closest focus point at which everything out to infinity is still sharp. Focus there, and the sharp zone starts at half that distance. A 24 mm lens at f/8 on full frame has a hyperfocal distance of about 2.4 metres, so everything from about 1.2 metres to the horizon is sharp. The calculator shows the hyperfocal distance for every setting.

Front and back

The results also split the zone into the part in front of the subject and the part behind, with the percentage in front. At typical distances about a third lies in front and two thirds behind; at macro distances the split approaches even.

The formulas

The calculator uses the standard thin-lens equations. Hyperfocal distance H equals the focal length squared divided by aperture times circle of confusion, plus the focal length. The near limit is s(H − f) / (H + s − 2f) and the far limit s(H − f) / (H − s), becoming infinite when the focus distance reaches H.

What changes depth of field

Stopping down from f/2.8 to f/8 deepens the zone a lot. Stepping back from the subject deepens it too. A longer focal length at the same distance makes it thinner. A smaller sensor, with the same framing, gives more depth at the same f-number, which is why phones struggle to blur backgrounds optically.

Limits of the model

The thin-lens formulas are an excellent approximation for normal lenses but less exact for very close focusing, extreme wide-angles and lenses with strong focus breathing. Sharpness also falls off gradually rather than at a hard line.

Related tools

For close-up work with tubes or bellows, use the Macro Extension Calculator. To compare framing across sensors, see the Crop Factor Calculator. Long exposures at small apertures pair well with the ND Filter Calculator.