Binocular field of view converter: feet, metres and degrees
Binocular makers print field of view in different units: feet at 1,000 yards, metres at 1,000 metres, or degrees. This free converter turns any one into the other two, then shows how wide a patch of scene you will see at the distance you actually bird. Nothing is sent anywhere; it runs in your browser.
Convert a field of view
How the conversion works
Field of view is an angle. A width of 1 unit seen at 1,000 of the same unit is about 0.0573 degrees, so for the metric figure you divide by 17.45 to get degrees (1,000 ÷ 57.2958). For the imperial figure, 1,000 yards is 3,000 feet, so you divide feet by 52.4 (3,000 ÷ 57.2958); most makers round that to 52.5. To go the other way, multiply degrees by 52.4 for feet at 1,000 yards or by 17.45 for metres at 1,000 metres. The width at a closer distance is the distance times the tangent of the angle, which is very nearly the distance times degrees ÷ 57.3 for these small angles.
A figure in feet is always about 3 times the metric one for the same binocular: 330 ft at 1,000 yd is the same view as 110 m at 1,000 m, which is 6.3 degrees.
Common values at a glance
| Feet at 1000 yd | Metres at 1000 m | Degrees | Width at 30 m | Typical for |
|---|---|---|---|---|
| 300 | 100 | 5.7 | 3.0 m | 10x pairs, narrower end |
| 330 | 110 | 6.3 | 3.3 m | 8x pairs, narrower end |
| 360 | 120 | 6.9 | 3.6 m | 10x wide-angle, or an average 8x |
| 393 | 131 | 7.5 | 3.9 m | a good 8x42 |
| 420 | 140 | 8.0 | 4.2 m | wide-angle 8x |
The "typical for" column is a rough guide from common spec sheets, not a rule. Compare like with like: a field of view is only meaningful next to another pair of the same magnification, because higher power always narrows the view.
Why it matters for finding birds
When a warbler jumps to the next branch, you raise the binoculars to where you last saw it. A wider field gives you more room for error and makes it quicker to land on the bird. Beginners often struggle more with a narrow field than with brightness, which is one reason lower magnification is the usual advice. Note that manufacturers measure the figure at the edge of a sharp picture or at the very edge of the circle, and the methods differ, so treat a few percent of difference between brands as noise.
Also watch for "apparent field of view", a different number (the width of the view as it seems to your eye, often 60 to 70 degrees) that is not the same as the real field of view above. Only use the real one for this converter.
Next steps
Check the other numbers on a spec sheet with the binocular spec decoder, learn the basics at what 8x42 means, or see how the choice plays out in the 8x42 versus 10x42 comparison.