A C-rating is the maximum discharge current expressed as a multiple of capacity. 1C equals the pack's capacity in amps. A 1500 mAh (1.5 Ah) pack rated 75C can deliver up to 75 times 1.5, which is 112.5 amps continuously.

How is the maximum current calculated?

Max current in amps equals capacity in amp-hours times the C-rating. Capacity in mAh is divided by 1000 to get amp-hours first. So 1500 mAh at 75C is 1.5 times 75, equal to 112.5 A continuous.

What is the difference between continuous and burst?

Continuous is the current the pack can sustain indefinitely without overheating. Burst is a higher current it can deliver only for a few seconds, such as during a hard punch-out. Never design around burst as if it were continuous.

Are manufacturer C-ratings accurate?

Many hobby-grade packs overstate their C-rating for marketing. A real-world rule is to treat the printed continuous figure as optimistic and keep your actual draw well below it, perhaps 60 to 80 percent, for cooler cells and longer pack life.

How does this relate to flight time and ESC choice?

The continuous current limit must comfortably exceed your craft's average draw, and the burst limit must exceed peak draw. Your ESC rating must also clear the same peaks. Use a capacity calculator for flight time and an ESC sizing calculator for the controller.

What is the LiPo C-Rating & Max Burst Current Calculator?

Enter LiPo battery capacity in mAh, continuous C-rating, and burst C-rating to compute the maximum safe continuous and peak current draw in amps. For RC and FPV drone builders avoiding over-discharge and battery damage. It runs free in your browser on Gera Tools, with nothing uploaded.

LiPo C-Rating & Max Burst Current Calculator

Name: LiPo C-Rating & Max Burst Current Calculator
Creator: Gera Tools
License: https://creativecommons.org/licenses/by/4.0/

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A LiPo’s C-rating tells you how hard you can pull on it before you risk overheating, puffing, or fire. This calculator converts the C-ratings printed on your pack into real current limits in amps, separating the current you can draw all day from the brief burst the pack can survive.

How it works

The C-rating is a multiplier on capacity expressed in amp-hours:

capacity Ah      = capacity mAh / 1000
max continuous A = capacity Ah × continuous C
max burst A      = capacity Ah × burst C

Continuous is the figure to design around. Burst applies only for a few seconds during a hard punch-out or full-throttle sprint, so never design your system to run at the burst limit — that is a damage threshold, not a working spec.

Worked example

For example, a 1300 mAh pack rated 100C continuous / 200C burst:

Capacity in Ah: 1300 ÷ 1000 = 1.3 Ah
Max continuous current: 1.3 × 100 = 130 A
Max burst current: 1.3 × 200 = 260 A

Because many hobby-grade packs overstate their C-rating, a practical working limit is around 60–70% of the stated continuous figure — roughly 80–90 A here — for cooler cells and longer pack life.

How C-ratings affect ESC and motor choice

The battery’s continuous current limit must comfortably exceed the total current your motors draw at full throttle. For a typical 5-inch FPV quad running four 2306 motors at around 30 A each, that is 120 A total. A 1500 mAh 75C pack delivers 1.5 × 75 = 112.5 A continuous — borderline. Moving to a 100C pack or a larger capacity (for example, 1800 mAh at 75C = 135 A) gives the headroom needed for aggressive flying without sustained over-discharge.

Your ESC rating must also clear the peak draw per motor; match both the battery current limit and the ESC amp rating to your motor and propeller combination for reliable, safe builds.

Signs a pack is being over-discharged

Pack becomes noticeably hot after a flight (warm is fine; hot enough to be uncomfortable to hold is not)
Pack puffs or swells between flights — this is a safety hazard and the pack should be disposed of safely
Voltage sag under full throttle is severe, causing ESC brownouts or motor shutdowns
Pack capacity drops noticeably over a small number of charge cycles

If you see these signs, the easiest fix is to reduce your flight aggressiveness, set a lower throttle ceiling, or upgrade to a pack with more capacity or a higher stated C-rating. Over-discharged packs degrade quickly and carry a thermal runaway risk; do not continue flying a pack that is consistently hitting these symptoms.

Storing LiPo packs safely

Most LiPo chargers have a storage charge mode that brings the pack to approximately 3.8 V per cell — the recommended long-term storage voltage. Storing at full charge (4.2 V/cell) or fully discharged accelerates capacity degradation. If a pack will sit unused for more than a week, storage-charge it and keep it in a LiPo-safe bag at room temperature.