Shutter Speed Calculator — Exposure Triangle
Enter your aperture (f-number), ISO and the lighting condition (or a manual EV) to find the shutter speed that produces a correct exposure. The curve shows how changing ISO trades off against shutter time for the same scene.
Lighting / scene
1/2090 s — time the sensor is exposed
- 1
Aperture squared
5.6² = 5.6 × 5.6 = 31.36 - 2
2^EV (scene power)
2^15 = 32,768Scene luminance as a power of 2; each integer EV step is one photographic stop. - 3
Shutter time
31.36 × 100 ÷ (32,768 × 200) = 0.000479 s - 4
Required speed (1/t)
1 ÷ 0.000479 = 2,090
How does this calculator work?
Required shutter time t = N² × 100 / (2^EV × ISO), where N is the f-number, EV the scene exposure value at ISO 100 (sunny day ≈ 15, indoor ≈ 8), and ISO the sensor sensitivity. Halving the shutter speed or doubling ISO are equivalent one-stop trades. The Sunny-16 rule (t ≈ 1/ISO at f/16) is a special case.
Formula
How this is calculated
Camera exposure is governed by three variables — aperture (N, the f-number), shutter time (t, in seconds), and sensor sensitivity (ISO, S). Together they determine how much light reaches the sensor: doubling ISO halves the required shutter time; opening the aperture by one stop (e.g. f/8 → f/5.6, which halves N²) also halves the shutter time. The exposure-value (EV) scale captures the scene's luminance as a single number at ISO 100; each integer step is one stop (factor of 2).
The formula t = N² × 100 / (2^EV × S) rearranges the EV definition EV = log₂(N²/t) to account for ISO. At EV 15 (bright sunlight) with f/5.6 and ISO 200: t = 31.36 × 100 / (32768 × 200) ≈ 1/2090 s, so a 1/2000 s shutter is correct — consistent with the sunny-16 rule.
The XY curve below shows shutter speed (expressed as 1/t) versus ISO for your chosen aperture and scene, illustrating the linear trade-off. Limitations: the formula assumes a reflected-light metering constant K = 12.5 (the international standard, used by Canon, Nikon, Sony). Incident-light meters use a different constant. Reciprocity failure at very long exposures (film only) and motion-blur requirements are outside this model.
Frequently asked questions
At f/16 on a sunny day, a correct exposure uses ISO as the denominator of the shutter speed: at ISO 100 use 1/100 s; at ISO 200 use 1/200 s. This calculator generalises that rule to any aperture and lighting condition via the EV formula.
As a guideline: walking people ≈ 1/125 s; sports or cyclists ≈ 1/500–1/1000 s; birds in flight ≈ 1/2000 s; fast vehicles ≈ 1/4000 s. Raise ISO or open the aperture to achieve the required speed in low light.
Typical indoor values at ISO 100: bright office or studio ~EV 10; average living room ~EV 7–8; candlelit dinner ~EV 5–6; stage / spotlit performance ~EV 7. Switch ISO to 400–3200 to get workable shutter speeds without blur.
Also known as
TG we-Calculate Editorial Team. (2026). Shutter Speed Calculator — Exposure Triangle [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/shutter-speed-calculator
TG we-Calculate Editorial Team. "Shutter Speed Calculator — Exposure Triangle." TG we-Calculate. 2026. https://we-calculate.com/calculator/shutter-speed-calculator.
TG we-Calculate Editorial Team, "Shutter Speed Calculator — Exposure Triangle," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/shutter-speed-calculator
@misc{wecalculate_shutter_speed_calculator, title = {Shutter Speed Calculator — Exposure Triangle}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/shutter-speed-calculator}}, year = {2026}, note = {TG we-Calculate} }
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