What is RCF (relative centrifugal force)?

RCF is the effective force applied to the sample in a centrifuge, expressed as multiples of gravitational acceleration (×g). RCF = 1.118 × 10⁻⁶ × n² × R, where n is RPM and R is rotor radius in mm. Unlike RPM, RCF accounts for rotor size, making it comparable across different centrifuges.

Why should I use RCF instead of RPM in protocols?

RPM alone doesn't specify the actual force on the sample — it depends on rotor radius. Two centrifuges at the same RPM but different rotor sizes produce different g-forces. Scientific protocols specify RCF (×g) to ensure reproducible results regardless of the centrifuge model used.

What radius should I use — maximum, minimum, or average?

Use the maximum radius (r_max) — the distance from the rotation axis to the bottom of the sample tube — for the reported RCF. This gives the maximum g-force experienced by the sample. Some protocols specify r_avg (average) for sedimentation calculations.

What g-forces do different centrifuges achieve?

Typical ranges: benchtop microcentrifuges up to 20,000 ×g, general lab centrifuges 3,000–15,000 ×g, high-speed centrifuges 25,000–100,000 ×g, ultracentrifuges up to 1,000,000 ×g. Industrial separators typically operate at 1,000–10,000 ×g.

How do I convert g-force back to RPM?

Use the reverse formula: n = √(RCF / (1.118 × 10⁻⁶ × R)), where RCF is the desired g-force and R is rotor radius in mm. This calculator supports both directions — toggle between 'RPM → RCF' and 'RCF → RPM' modes.

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離心機 G 力 (RCF) 計算器

將離心機 RPM 轉換為相對離心力 (×g)，或根據所需 RCF 計算 RPM。包含葉尖速度與角速度。

RPM → RCF RCF → RPM 葉尖速度

結果

相對離心力 (RCF)

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RPM

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葉尖速度

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角速度 ω

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相對離心力 (RCF)

RCF 是作用於樣品的有效力，以重力加速度的倍數表示：

n — 轉速 (RPM)
R — 轉子半徑，單位 mm（旋轉中心至樣品位置）
1.118 × 10⁻⁶ — 來自 (2π/60)²/(9.81×1000) 的組合常數

反向：由 RCF 計算 RPM

典型 RCF 值

應用	典型 RCF (×g)	典型 RPM
血液分離	1,000–3,000	2,000–5,000
細胞沉澱	300–500	1,000–2,000
蛋白質沉澱	10,000–20,000	10,000–15,000
亞細胞分級	20,000–100,000	15,000–50,000
超速離心	100,000–1,000,000	40,000–100,000
工業分離機	1,000–10,000	3,000–10,000

實務範例

範例 — 實驗室離心機

已知： R = 100 mm，轉速 = 5000 RPM

RCF = 1.118 × 10⁻⁶ × 5000² × 100 = 2,795 ×g

ω = 2π × 5000 / 60 = 523.6 rad/s

Tip speed = 0.1 × 523.6 = 52.4 m/s

💡 提示： 在科學實驗步驟中，應始終以 RCF (×g) 而非 RPM 來報告離心機條件。這可確保在不同轉子尺寸的不同離心機型號之間具有可重複性。