Night Navigation Calculator

Headlamp runtime and battery needs for night sections.

Night section (hrs)

Headlamp brightness (lumens)

Battery capacity (mAh)

Number of headlamps

Terrain Difficulty

Moving time (%)

Tab to move between fields

High-mode runtime (hrs)

Battery drain (%)100

Battery sets needed2

Spare batteries1

Battery weight (g)96

Speed penalty (%)40

Recommended lumens300

Lumen adequacy (%)100

Moving time (hrs)6.4

Off (hrs)0.8

How to Use This Calculator

Enter Night section (hrs), Headlamp brightness (lumens), and Battery capacity (mAh).
Set Number of headlamps, Terrain Difficulty, and Road / path.
Adjust Maintained trail, Off-trail hiking as needed.
Review the High-mode runtime (hrs) result.
Use Battery drain (%) and Battery sets needed to inform your decision.

How the result changes with Headlamp brightness (lumens)

Night section (hrs): Hours of racing/travel in darkness.
Headlamp brightness (lumens): Peak output of your headlamp in lumens.
Battery capacity (mAh): Battery capacity in milliamp-hours (e.g., 18650 = 3000-3500mAh).
Number of headlamps: Number of headlamps carried (primary + backup).
Terrain Difficulty: Night terrain conditions.
Moving time (%): Percentage of night time spent actively moving vs. stopped.

High-mode runtime (hrs): How long the battery lasts on max brightness.
Battery drain (%): Estimated battery usage for the night section.
Battery sets needed: Total number of battery changes needed.
Spare batteries: Number of spare battery sets to carry.
Battery weight (g): Total weight of all batteries including spares.
Speed penalty (%): Expected reduction in travel speed at night.
Recommended lumens: Minimum recommended brightness for your terrain.
Lumen adequacy (%): How your headlamp compares to recommended brightness.
Moving time (hrs): Hours you will actually be moving during the night section.

Identify Input Parameters
4 parameters
Night section (hrs) = 8, Headlamp brightness (lumens) = 300, Battery capacity (mAh) = 3000, Number of headlamps = 1 = 6 input(s) provided
Calculate High-mode runtime
High-mode runtime = (batteryCapacityMah * voltage) / (powerDrawW * 1000)
3 = 3
Calculate Battery drain
Battery drain = min(100, (effectiveBurnHrs / highModeRuntimeHrs) * 100)
100 = 100
Calculate Battery sets needed
Battery sets needed
2 = 2