Depth of Field & Hyperfocal Calculator
Near, far and hyperfocal distances — and why the one-third rule is true at exactly one distance, set by the focal length over the hyperfocal distance.
Depth of field is a judgement, not a measurement: it depends on a chosen circle of confusion, which assumes a print size, a viewing distance and ordinary eyesight. Pixel-peeping at 100% applies a far stricter test than any of these numbers do, so treat the limits as where things stop looking sharp rather than where they stop being sharp. Nothing is uploaded.
The one-third rule is true at exactly one distance
Close in the split is almost even — 49% in front at 0.2 m — and it falls the whole way out, collapsing to nothing once the far limit runs to infinity. It passes one third somewhere in the middle, and that somewhere is a fraction of the hyperfocal distance. For a long lens at a wide aperture the fraction is exactly one third (0.3334 for a 400 mm at f/1.4) — but it is not a constant. It climbs to 0.3624 for a 14 mm at f/22, and what it climbs with is f/H and nothing else.
| Subject | Near | Far | In front |
|---|---|---|---|
| 0.2 m | 0.20 m | 0.20 m | 49.3% |
| 0.3 m | 0.29 m | 0.31 m | 48.8% |
| 0.5 m | 0.48 m | 0.52 m | 47.9% |
| 1 m | 0.92 m | 1.10 m | 45.6% |
| 2 m | 1.69 m | 2.44 m | 41.0% |
| 3 m | 2.36 m | 4.13 m | 36.3% |
| 5 m | 3.43 m | 9.25 m | 27.0% |
| 10 m | 5.20 m | 130.48 m | 3.8% |
| 20 m | 7.01 m | ∞ | 0.0% |
| 50 m | 8.87 m | ∞ | 0.0% |
A 50 mm at f/8 on full frame. The crossing distances themselves span four orders of magnitude — 116 mm for a 14 mm lens, over a kilometre for a 400 mm at f/1.4 — while the fraction moves only from 0.3334 to 0.3624. Focus at the hyperfocal distance itself and the near limit falls at exactly half of it, which is the one genuinely clean number in the whole subject.
| Lens | Split is 1/3 at | Hyperfocal | f/H | Fraction |
|---|---|---|---|---|
| 400 mm f/1.4 | 1314.029 m | 3941.29 m | 0.00010 | 0.3334 |
| 200 mm f/4 | 115.143 m | 345.03 m | 0.00058 | 0.3337 |
| 100 mm f/8 | 14.468 m | 43.20 m | 0.00231 | 0.3349 |
| 50 mm f/8 | 3.642 m | 10.83 m | 0.00462 | 0.3364 |
| 24 mm f/8 | 0.852 m | 2.51 m | 0.00957 | 0.3397 |
| 14 mm f/22 | 0.116 m | 0.32 m | 0.04359 | 0.3624 |
And f/H really is the whole of it. These two setups share nothing as equipment — different focal length, different aperture, different format — but they share an f/H, and their crossing fractions agree to five decimal places.
| Setup | Circle | f/H | Fraction |
|---|---|---|---|
| 200 mm f/11 | 0.037 mm | 0.00203 | 0.33469 |
| 400 mm f/22 | 0.037 mm | 0.00203 | 0.33469 |
| 50 mm f/2.8 | 0.037 mm | 0.00207 | 0.33471 |
| 200 mm f/22 | 0.019 mm | 0.00209 | 0.33472 |
A small sensor does not have more depth of field
At the same focal length and aperture a small format has less depth, not more — a tighter circle of confusion is a stricter test, so the hyperfocal distance goes up. The extra depth everyone associates with phones is real, but it comes from the shorter lens needed to frame the same subject. Framing a metre-wide subject from two metres takes a 69 mm on full frame and a 12 mm on a phone, and that is where the 6.1× comes from.
| Format | Sensor | Circle | Lens needed | Depth at f/4 |
|---|---|---|---|---|
| Full frame (35 mm) | 36 mm | 0.029 mm | 69 mm | 0.19 m |
| APS-C | 23.6 mm | 0.019 mm | 46 mm | 0.28 m |
| Micro Four Thirds | 17.3 mm | 0.015 mm | 34 mm | 0.41 m |
| 1 inch | 13.2 mm | 0.011 mm | 26 mm | 0.52 m |
| Phone (1/2.3 in) | 6.17 mm | 0.005 mm | 12 mm | 1.14 m |
Same subject, same distance, same f-number — only the format changes. Stopping down always adds depth, and roughly in proportion to the f-number, so two stops is about twice the depth until the far limit reaches infinity and the proportion stops meaning anything.
How to use
- Enter the focal length and aperture.
- Enter how far away the subject is.
- Pick the format you are shooting.
- Read the near and far limits, and the front-to-back split.
Frequently asked questions
Is a third of the depth really in front of the subject?
Only at one distance. Close in the split is almost exactly even, and it falls the whole way out until the far limit reaches infinity and the front share collapses to nothing. At two metres with a 50 mm at f/8 it is 41%, not 33%.
So when is the one-third rule right?
At about a third of the way to the hyperfocal distance. That fraction is not quite constant — it runs from exactly a third for a long lens at a wide aperture up to 0.362 for a 14 mm at f/22, and what it tracks is the focal length divided by the hyperfocal distance.
What is the hyperfocal distance?
The focus distance at which the far limit first reaches infinity. Focus there and everything from exactly half of it out to infinity is acceptably sharp, which is the single cleanest number in the whole subject.
Do small sensors have more depth of field?
Not at the same focal length — there they have LESS, because a tighter circle of confusion is a stricter test. The extra depth people associate with phones comes from the much shorter lens needed to frame the same subject.
Does focal length matter if I keep the framing?
Barely, once you are close. At half life size a 25 mm and a 200 mm give depths within 0.03% of each other. Further out it stops holding: by a fiftieth life size they differ by 27%, so it is a close-focus rule rather than a general one.
How much does stopping down help?
Roughly in proportion to the f-number, so two stops is about twice the depth — until the far limit reaches infinity, at which point the proportion stops meaning anything because the depth is already unbounded.
What is a circle of confusion?
The largest blur spot that still reads as a point. It assumes a print size, a viewing distance and ordinary eyesight, so it is a judgement rather than a measurement. Inspecting at 100% on screen applies a far stricter test than any standard figure.
Does this send anything anywhere?
No. Every figure is computed in your browser, and nothing is uploaded or stored.
🔒 This tool runs entirely in your browser. Nothing you enter is uploaded, logged, or stored.