Studio Lighting Ratio Calculator

Calculate key-to-fill lighting ratios for photography and film. Input your key and fill light power or f-stop difference to find contrast ratio, shadow density, and the look it produces.

Light Settings

Input Method

Key Light Power 400 Ws

Fill Light Power 200 Ws

Key Distance 6 ft

Fill Distance 8 ft

Background Light (relative) 50% of key

Hair / Rim Light 1.5× key

Lighting Analysis

Lighting ratio (K:F+K)—

F-stop difference—

Shadow density—

Contrast character—

Effective key lux (at subj.)—

Effective fill lux (at subj.)—

Background vs key—

Recommended for—

—

ratio

Contrast

—

f-stops

K over F

—

% fill

Shadow zone

—

look

Character

Standard Lighting Ratios Reference

Ratio	F-stops	Shadow %	Look	Best For

The calculators and tools on LightingCalc.lighting are provided for general guidance and informational purposes only. Results are estimates based on standard formulas and the values you enter — they do not constitute professional engineering, electrical, or architectural advice. Always verify calculations with a qualified professional before making decisions for any safety-critical, code-compliance, or commercial application. LightingCalc.lighting makes no representations or warranties as to the accuracy or completeness of any result, and accepts no liability for errors, omissions, or any outcomes arising from reliance on this information.