Start Capacitors (Motor Start Capacitors)

Motor Start Capacitor Range (Find the Right MFD Fast)

Use this guide to jump straight to the motor start capacitor you need for single-phase motors that are struggling to kick over. Start capacitors give a short burst of extra phase shift (and torque) at start-up, then drop out of circuit once the motor is running—so you get cleaner starts without cooking the windings.

Selection rule: match the original µF (MFD) shown on the motor/cap label (±10% is typical for start caps) and use the same or higher voltage rating—never lower. Always isolate power and safely discharge the old capacitor before handling.

Jump to Your Size

• 25–30 MFD 250V
• 31.5–40 MFD 250V
• 40–50 MFD 250V
• 50–63 MFD 250V
• 63–80 MFD 250V
• 72–88 MFD 250V
• 88–108 MFD 250V
• 108–130 MFD 250V
• 124–149 MFD 250V
• 145–174 MFD 250V
• 160–200 MFD 250V
• 189–227 MFD 250V
• 200–250 MFD 250V
• 216–260 MFD 250V
• 233–280 MFD 250V
• 250–315 MFD 250V
• 270–324 MFD 250V
• 315–400 MFD 250V
• 43–53 MFD 330V
• 72–88 MFD 330V
• 88–108 MFD 330V
• 108–130 MFD 330V
• 130–156 MFD 330V
• 145–174 MFD 330V
• 160–200 MFD 330V
• 250–315 MFD 330V

What’s Included (Standard Across the Range)

Every start capacitor in this range includes the key hardware you need for a tidy install. That means you’re not improvising brackets on site or leaving a capacitor floating in the compartment.

• End cap, mounting bracket & discharge resistor (built-in)
• P1 Safety Class
• Operating frequency: 50–60 Hz
• Rated voltage: 250 VAC or 330 VAC as specified

Start Capacitor 25–30 MFD 250V

This range is commonly used where a small single-phase motor needs a quick “kick” to start cleanly, then run on its normal circuit. You’ll see it in lighter duty fans and small pump/utility motors where the start circuit is simple but the motor still needs extra starting torque.

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Start Capacitor 31.5–40 MFD 250V

Used on a lot of common domestic/light-commercial gear where the motor can run fine once spinning, but struggles on start under load. It’s a handy “bread-and-butter” size for smaller pump motors and some older single-phase HVAC/refrigeration applications that use a start assist.

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Start Capacitor 40–50 MFD 250V

This is a common step up when the motor needs a stronger initial push, like on heavier fan loads or pumps starting against head pressure. If the symptom is “hums then trips” or slow start-up, this range is often worth checking against the original label.

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Start Capacitor 50–63 MFD 250V

Common on single-phase refrigeration compressors and motors that start under higher load, especially in older equipment. A correctly sized start cap here can reduce nuisance overload trips and get the motor up to speed faster—so it doesn’t sit cooking at locked-rotor.

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Start Capacitor 63–80 MFD 250V

Often used where the compressor or motor needs more starting torque to overcome pressure or friction at start-up. It’s a good match for many split-system style single-phase motors and commercial refrigeration compressors that need a stronger initial phase shift.

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Start Capacitor 72–88 MFD 250V

This range is popular for medium start loads where the equipment starts frequently or starts under warm conditions. If a unit starts fine in the morning but struggles in the arvo heat, a weak start cap in this band is a common culprit.

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Start Capacitor 88–108 MFD 250V

Used on motors that need a reliable kick to get moving without stalling—think larger fan assemblies and many compressor start circuits. The main goal is to shorten start time so the motor isn’t sitting at high current for longer than it should.

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Start Capacitor 108–130 MFD 250V

This is a stronger start-assist band for pumps and compressors that start under heavier load. When matched correctly, it helps prevent the classic “click… hum… trip” cycle by boosting starting torque just long enough to get up to speed.

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Start Capacitor 124–149 MFD 250V

Often used on larger single-phase motors that need a more serious shove on start-up, such as heavier duty pumps and compressor circuits. It’s a common size band when the system starts under load and the run winding alone can’t get it moving cleanly.

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Start Capacitor 145–174 MFD 250V

For high-start-load jobs where quick acceleration matters to protect windings and reduce thermal stress. You’ll see it on heavier compressor starts and larger pump motors, especially where warm ambient conditions make starting harder.

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Start Capacitor 160–200 MFD 250V

Commonly used in tougher compressor and pump start circuits where the motor must overcome load immediately. Matching this range correctly helps reduce start time and can cut nuisance overload trips on single-phase equipment.

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Start Capacitor 189–227 MFD 250V

This band suits very high starting torque requirements where the motor or compressor is slow to accelerate without help. It’s typically used where the start circuit needs a strong phase boost to get through the first second or two of start-up safely.

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Start Capacitor 200–250 MFD 250V

A heavy-duty start range for larger single-phase motors that start under significant load or frequent cycling. If the equipment is slow to start or trips on overload during start, this is a common label range you’ll see on replacement caps.

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Start Capacitor 216–260 MFD 250V

Used when you need serious start assist—think heavy compressor starts and high-load pump applications. The point is not “more is better”, it’s “correct is better”: match the label so the start circuit does its job and drops out as intended.

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Start Capacitor 233–280 MFD 250V

This band is for high torque starts where the motor needs to overcome load immediately, not gradually. It’s commonly seen in heavier duty single-phase systems where warm conditions or frequent starts make the start circuit work hard.

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Start Capacitor 250–315 MFD 250V

Built for demanding starts where the motor needs a strong initial push to avoid stalling and overheating. It’s a common spec range on larger compressor start circuits and heavy pump motors that start under load.

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Start Capacitor 270–324 MFD 250V

Often found on very tough start environments where head pressure, load, or ambient heat makes starting harder. When you match this range correctly, the motor reaches operating speed faster and spends less time pulling high start current.

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Start Capacitor 315–400 MFD 250V

This is one of the heaviest 250V start bands and is typically used on high-load single-phase compressor circuits. It’s aimed at shortening start-up time on big starts so you reduce thermal stress and nuisance trips.

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Start Capacitor 43–53 MFD 330V

This 330V range is used when the start circuit requires a higher voltage rating for extra margin and reliability. It’s common in modern HVAC/refrigeration applications where the OEM spec calls for 330VAC start caps—especially in warm, high-start-load conditions.

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Start Capacitor 72–88 MFD 330V

Used when you need the same style of start “boost” as the 250V range but with the added voltage headroom the OEM has specified. It’s a solid pick for compressor start circuits that run hot, cycle often, or start under higher load.

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Start Capacitor 88–108 MFD 330V

This is a common 330V band for compressor start circuits that need reliable starting torque without long start times. When the start cap is weak, you’ll often see slow starts, humming, and overload trips—replacing like-for-like usually fixes it fast.

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Start Capacitor 108–130 MFD 330V

Suited to heavier start loads where the OEM calls for 330VAC for extra margin. It’s commonly used on stubborn compressor starts, helping the motor accelerate quickly so it doesn’t sit pulling high current.

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Start Capacitor 130–156 MFD 330V

This range supports motors and compressors that need strong start assist, especially in high ambient temperature environments. It’s a good fit when start performance degrades in summer and the OEM spec calls for a higher voltage rating.

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Start Capacitor 145–174 MFD 330V

For heavy compressor start circuits where quick acceleration prevents overheating and nuisance trips. If the unit is slow to start or trips under load, replacing the start cap in this band (like-for-like) is often a fast win.

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Start Capacitor 160–200 MFD 330V

This is a heavy-duty 330V range for demanding starts on larger compressors and high-load single-phase systems. The goal is to get the motor up to speed quickly so the start circuit can drop out and the run winding can take over safely.

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Start Capacitor 250–315 MFD 330V

One of the strongest start-assist bands for single-phase compressor circuits where the OEM has specified 330VAC. It’s used in the most demanding start situations to reduce start time, limit locked-rotor stress, and keep the system reliable.

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Useful Add-Ons & Related Items

• Motor Start Capacitors (Full Range) – Jump straight to the correct MFD and voltage so you can order fast and get the unit starting cleanly again.
• SUPCO Super Boost Hard Start Kit – A bundled option (capacitor + relay) that can help stubborn compressors start faster and reduce nuisance trips.
• Motor Run Capacitors (Fixed 8 mm Bolt) – Handy when you’re replacing both start and run components in the same compartment for a more reliable long-term fix.