How to Calculate a resistor value for SMD Resistors

This easy SMD resistors Codes calculator will assist you decide the fee of any SMD resistor. To get started, enter the three or four digit code and hit the “Calculate” button or Enter.

Note: The application became examined rigorously, however it nonetheless can also additionally have some bugs. So, whilst in doubt (and whilst it is possible) do not hesitate to apply a multimeter to double-test the essential components.

See additionally the Color code calculator in this web page for MELF and general through-hollow resistors.

Most chip resistors are marked with a three-digit or four-digit code — the numerical equal of the acquainted shadeation code for through-hollow components. Recently, a brand new coding system (the EIA-ninety six) has seemed on precision SMDs.

The three-digit code

Standard-tolerance SMD resistors are marked with a easy three-digit code. The first numbers will suggest the enormous digits, and the 0.33 might be the multiplier, telling you the strength of ten to which the 2 enormous digits ought to be multiplied (or what number of zeros to add). Resistances of much less than 10 ohms do now no longer have a multiplier, the letter ‘R’ is used as an alternative to signify the placement of the decimal factor.

The following desk lists all typically used 3-digit SMD resistors from 0.1 ohm to 9.1 Mohms. See additionally the SMD resistor calculator and a brief academic on the way to discover the fee of SMD resistors.

The four-digit code

The four-digit code is used for marking precision floor mount resistors. It’s just like the preceding system, the best distinction is the range of enormous digits: the primary 3 numbers will inform us the enormous digits, and the fourth might be the multiplier, indicating the strength of ten to which the 3 enormous digits ought to be multiplied (or what number of zeros to add). Resistances of much less than a hundred ohms are marked with the assist of the letter ‘R’, indicating the placement of the decimal factor.

The following tables listing all typically used four-digit SMD resistors from 0.1 ohm to 9.seventy six Mohms (E24 and E96 series). See additionally the SMD resistor calculator and a brief academic on the way to calculate the fee of an SMD resistor.

EIA-ninety six

Recently, a brand new coding system (EIA-ninety six) has seemed on 1% SMD resistors. It includes a 3 individual code: the primary 2 numbers will inform us the three enormous digits of the resistor fee (see the research desk under) and the 0.33 marking (a letter) will suggest the multiplier.

Notes:

an SMD resistor with a marking of 0, 00, 000 or 0000 is a jumper (a zero-ohm link).
a chip resistor marked with the same old three digit code and a brief bar under the marking denotes a precision (1% or much less) resistor with a fee taken from the E24 series (those values are typically reserved for 5% resistors). For example: 122 = 1.2kΩ 1%. Some producers underline all 3 digits — do now no longer confuse this with the code used on low fee modern-day sensing resistors.

SMDs with values so as of milliohms, made for modern-day sensing packages are frequently marked with the assist of the letters M, m or L, displaying the decimal factor location (with the fee in milliohms). For example: 1M50 = 1.50mΩ, 2M2 = 2.2mΩ, 5L00 = 5mΩ.

Current sensing SMDs also can be marked with a protracted bar on top (1m5 = 1.5mΩ, R001 = 1mΩ, etc.) or a protracted bar below the code (101 = 0.101Ω, 047 = 0.047Ω). The underline is used whilst the starting ‘R’ needs to be ignored because of the constrained area at the resistor’s body. So, for example, R068 will become 068 = 0.068Ω (68mΩ).

Power score

SMD resistor dimensions

To discover the approximative strength score of your SMD resistor, degree its duration and width. A few typically used package deal dimensions with the corresponding traditional strength rankings are provided withinside the desk under. Use this desk as a manual best, and constantly seek advice from the component’s datasheet for the precise fee.

Tolerance

The general three and four digit code does now no longer provide us a manner to decide the SMD resistor’s tolerance.

In maximum cases, however, you may discover that a floor mount resistor marked with the three-digit code has a tolerance of 5% and a resistor marked with four-digit code or the brand new EIA-ninety six code has a tolerance of 1% or much less.

There are many exceptions to this rule, so constantly test the manufacturer’s datasheet, mainly if the component’s tolerance is essential in your application.