Pick a servo by torque first, then speed and size. A 9 g micro servo suits small foam planes, while a standard servo with 3 kg-cm or more suits larger planes and 1:10 cars. Metal gears last longer under load than plastic gears. Digital servos hold position better than analog servos. Match the mount to the servo case.
What torque does an RC plane servo need?
A small foam plane flies fine on 1.5 to 2.5 kg-cm of torque. A 9 g servo gives about that much, and it weighs only 9 g.
A larger sport plane needs 3 to 6 kg-cm on each surface. A standard servo near 40 g delivers that torque with margin.
What torque does an RC car servo need?
A 1:10 touring car steers well with 6 to 10 kg-cm of torque. Speed near 0.10 sec per 60 degrees keeps steering sharp.
A 1:10 drift car or crawler needs 12 kg-cm or more. A 12 kg digital servo turns big tires without stalling.
Should you pick metal or plastic gears?
Plastic gears are light and cheap, and they suit small planes under 500 g. A hard crash can strip them, so keep a spare on hand.
Metal gears handle 3 kg-cm loads and hard landings without stripping. They cost more, but one metal-gear servo often outlasts two plastic ones.
What is the difference between analog and digital servos?
An analog servo updates its position about 50 times per second. That is fine for sport flying and bashing on a budget.
A digital servo updates near 300 times per second, so it holds center better. It draws more current, so feed it from a 5 V BEC rated 3 A or more.
How do you mount a servo in a plane or car?
Match the servo case to the mount: a 9 g servo fits a 23 mm by 12 mm pocket. A standard servo fits a 40 mm by 20 mm pocket.
Use the horn that matches the spline count, often 25 teeth on standard servos. A 25T horn set gives four arm choices for one servo.
How do you power servos from a receiver?
A receiver pack or BEC must supply 5 V at the peak current of all servos. Four digital servos can pull 3 A under load.
A 5 A UBEC on a 2S to 8S pack covers most sport setups. Check the servo lead length too: 6 inch extensions reach wing servos, and 12 inch extensions reach tail servos.
Frequently asked questions
Can a 9 g servo steer a 1:10 RC car?
No. A 9 g servo gives near 2.5 kg-cm of torque, and a 1:10 car needs 6 kg-cm or more. Use a standard servo for car steering.
How do I know if my servo is digital or analog?
Digital servos list a high update rate, often near 300 Hz, on the product page. Analog servos list about 50 Hz instead.
Do metal-gear servos need a stronger BEC?
They can draw more current under load, so a 5 A UBEC is a safe match. A 3 A BEC covers two or three small metal-gear servos.
What servo horn fits a standard servo?
Most standard servos use a 25-tooth spline. A 25T horn set fits Futaba, TowerPro, and Power HD standard servos.
Parts used
SG92R Analog Plastic Composite Gear Micro Servo, $8.00. US stock, ships fast from NY, USA. Towerpro SG92R Analog Plastic Composite Gear Micro Servo. Torque: 2.5 kg/cm at 4.8V; Speed: 0.1 sec/60deg at 4.8V; Gears: plastic composite.
MA-90 Metal Gear Micro Servo, $8.00. US stock, ships fast from NY, USA. Torkstar MA-90 Metal Gear Micro Servo. Torque: 1.3 kg/cm (18.1 oz/in); Speed: 0.10 sec/60deg at 4.8V; Dimensions: 24 x 12.2 x 30 mm.
SG50 5g Micro Servo, $9.00. US stock, ships fast from NY, USA. Towerpro SG50 5g Micro Servo. Torque: 0.6 kg/cm (8.3 oz/in); Speed: 0.1 sec; Weight: 5g.
MG90D Digital Metal Gear Micro Servo, $14.00. US stock, ships fast from NY, USA. Towerpro MG90D Digital Metal Gear Micro Servo. Weight: 13g; Gears: metal; Digital: True.
1250MG Metal Gear 25g Mini Servo, $18.00. US stock, ships fast from NY, USA. Power HD 1250MG Metal Gear 25g Mini Servo. Torque: 3.5 kg-cm (48.6 oz/in) at 6.0V; Speed: 0.14 sec; Dimensions: 31.0 x 16.3 x 29.5 mm.
DSM-44 Digital Metal Gear Micro Servo, $22.00. US stock, ships fast from NY, USA. Power HD DSM-44 Digital Metal Gear Micro Servo. Torque: 1.6 kg/cm (18.0 oz/in); Speed: 0.07 sec; Dimensions: 22 x 8.7 x 22 mm.
SA-44 4.4g Metal Gear Sub-Micro Servo, $10.00. US stock, ships fast from NY, USA. Torkstar SA-44 4.4g Metal Gear Sub-Micro Servo. Torque: 0.8 kg/cm (9.3 oz/in); Speed: 0.12 sec; Dimensions: 20 x 26 x 8.0 mm.
Dilwe SPT4412LV 12KG Digital Servo Large Torsion Metal Gear for 1:10 RC Drift Car, $53.99. Dilwe SPT4412LV 12KG digital servo with large torsion metal gear for 1:10 RC drift cars. 0.09 sec per 60 degrees at 6V, 12 kg.cm stall torque, 2 ball bearings. Ships from NY, USA.
4-Point Aluminum Servo Arm Horn Set with Rudder Angle Ball Link, RC Aircraft, 2-Pack, $8.37. 4-point aluminum alloy servo arm horn set with rudder angle ball link for RC aircraft, racing drones and airplanes. Two triangle horns plus glass fiber plate, ball link and hardware. Ships from NY, USA.
25T Extended Metal Servo Horn, $7.99. Extended 25T metal servo horn arm for RC car, boat, and airplane servos. Red or black. Ships from NY, USA.
Servo Arms, Extensions and Testers
Related buying guides on Quality RC Parts
How to Choose Servos for RC Planes and Cars
How to Choose Servos for Your RC Car or Truck
How to Fit Servo Arms, Horns, and Testers for RC Use
Browse all the guides on the Quality RC Parts Drone Guides hub, or start at the Quality RC Parts store.
Sources
Quality RC Parts stocks parts in New York, USA and ships in-stock orders in 1-2 business days.
Last updated: 2026-11-10.