| Need | What to check first | Header style to look for | Example product family in this category | Common mistake to avoid |
|---|---|---|---|---|
| Breadboard or female Dupont jumper connection | Measure pitch center-to-center between adjacent pins first; breadboards, Arduino, and Raspberry Pi commonly use 2.54mm (0.1") | Straight male pin header in single row | 1x40 Male Header - 2.54mm Pitch | Ordering a 2.0mm or 1.27mm strip because it looks similar in photos |
| Receiving existing male pins on a module or board | Match the mating side: female header receives male pins | Straight female pin header in the needed count | 1x40 Female Header - 2.54mm Pitch | Buying only male strips and having nothing compatible to plug into |
| Raspberry Pi GPIO footprint | Check row format before pin count; Raspberry Pi GPIO uses a 2×20 dual-row footprint | Straight or right-angle 2×20 header | 2x20 Male Header - 2.54mm Pitch or 2x20 Female Header - 2.54mm Pitch for Raspberry Pi boards | Buying a single-row 1×40 because the listing also says “40 pin” |
| Compact board that measures 2mm pitch | Confirm the board is truly 2.0mm; that family is separate from 2.54mm | 2.0mm single-row or dual-row header | 1x40 Male Header - 2mm Pitch or 1x40 Female Header - 2mm Pitch | Confusing 2.50mm JST XH with 2.54mm header spacing, or treating 2.0mm as close enough |
| Fine-pitch board that measures 1.27mm | Check pitch carefully; 1.27mm is its own family | 1.27mm male or female strip | 1x40 Male Header - 1.27mm Pitch or 1x40 Female Header - 1.27mm Pitch | Ordering standard 2.54mm parts for a fine-pitch footprint |
| Side-entry or low-clearance layout | Decide from cable approach and enclosure space | Right-angle header | 1x40 Right Angle Male Header - 10mm Pin or 2x20 Right Angle Female Header | Assuming straight and right-angle parts are interchangeable for breadboard use |
Male header is the usual choice for female Dupont jumpers and breadboards. Female header is the one to choose when the board already has exposed male pins. Arduino R3 boards translate to separate single-row pieces in 6-pin, 8-pin, and 10-pin counts, while ESP32 devkits usually use two single rows, often 15–20 pins each. That is why breakaway single-row stock is usually the practical fit for ESP32 boards. Straight headers suit breadboards and vertical stacking. Right-angle parts fit side-entry or low-clearance layouts.
| Product family | Pitch | Row format | Orientation | Length or body-height detail | Electrical rating if stated | Best-fit use |
|---|---|---|---|---|---|---|
| 1x40 Male Header - 2.54mm Pitch | 2.54mm | 1×40 single row | Straight | — | — | Baseline 2.54mm header connector for breadboard and general prototyping |
| 1x40 Female Header - 2.54mm Pitch | 2.54mm | 1×40 single row | Straight | — | — | Baseline receiving socket for standard male pins |
| 1x40 Right Angle Male Header - 10mm Pin | 2.54mm | 1×40 single row | Right-angle | Approx. 10mm pin length | — | Side-entry layouts using a right angle pin header |
| 1x40 Male Long Header - 21mm Pin | 2.54mm | 1×40 single row | Straight | 21mm pin height | — | Extra vertical clearance or temporary breadboard/PCB connections |
| 1x40 Male Long Centered Header - 15mm Total | 2.54mm | 1×40 single row | Straight | 15mm total length, 6.25mm each side | — | Balanced reach above and below the board |
| 1x6 Female Long Header - 11mm Pin | 2.54mm | 1×6 single row | Straight | 11mm pin length | 3A current rating | Taller female option for compact board connections |
| 1x6 Female Long Header - 3mm Pin | 2.54mm | 1×6 single row | Straight | 8.5mm plastic body height, 3mm pin length | 550V AC | Low-profile 1×6 female option where extra reach is not needed |
| 1x8 Female Long Header - 11mm Pin | 2.54mm | 1×8 single row | Straight | 11mm pin length | 3A current rating | Board-to-board connections needing more height |
| 1x8 Female Header - 2.54mm Pitch | 2.54mm | 1×8 single row | Straight | 8.5mm plastic body height, 3mm pin length | — | Lower-profile female connection points |
| 1x10 Female Long Header - 11mm Pin | 2.54mm | 1×10 single row | Straight | 11mm pin length | — | Longer single-row female runs where 10 positions are needed |
| 2x3 Female Long Header - 11mm Pin | 2.54mm | 2×3 dual row | Straight | 8.5mm body height, 11mm pin length | — | ICSP and debug-style 2×3 footprints |
| 2x20 Male Header - 2.54mm Pitch | 2.54mm | 2×20 dual row | Straight | — | — | Common 40-position dual-row format for Raspberry Pi and similar layouts |
| 2x20 Female Header - 2.54mm Pitch | 2.54mm | 2×20 dual row | Straight | — | — | Dual-row receiving socket in the common 40-position format |
| 2x20 Right Angle Female Header | 2.54mm | 2×20 dual row | Right-angle | 40 total positions | — | Side-access dual-row layouts |
| 2x40 Male Header - 2.54mm Pitch | 2.54mm | 2×40 dual row | Straight | 80 total pins | — | High pin-count dual-row boards at standard pitch |
| 1x40 Male Header - 2mm Pitch | 2mm | 1×40 single row | Straight | — | — | Compact boards that specifically require 2.0mm spacing |
| 1x40 Female Header - 2mm Pitch | 2mm | 1×40 single row | Straight | — | 250V AC/DC | 2.0mm receiving socket with stated electrical rating |
| 2x40 Male Header - 2mm Pitch | 2mm | 2×40 dual row | Straight | 80 total pins | — | Dual-row 2.0mm layouts where pin count matches 2.54mm options but pitch does not |
| 1x40 Male Header - 1.27mm Pitch | 1.27mm | 1×40 single row | Straight | Compact footprint | — | Fine-pitch board interfaces |
| 1x40 Female Header - 1.27mm Pitch | 1.27mm | 1×40 single row | Straight | — | 1A rated current | Fine-pitch receiving socket where dense spacing matters |
| 1x40 Machine Pin Female Header - Gold Plated | 2.54mm | 1×40 single row | Straight | Machine pin construction | Half gold-plated surface technology | Premium female pin header for cleaner repeated mating |
| 1x40 Machine Round Pin Male Header - Press-fit | 2.54mm | 1×40 single row | Straight | Machine round pins, press-fit insertion | Gold-plated finish | Alternative to standard stamped strips when no-solder press-fit insertion is the priority |
Choose standard unshrouded headers when the connection needs to stay removable for prototyping, module swapping, or breadboard work. A basic 1x40 Male Header - 2.54mm Pitch or 1x40 Female Header - 2.54mm Pitch is the normal fit here.
Solder wires directly only when the build is final and will never change. That removes the connector entirely and saves height, but it also removes serviceability.
Move to screw terminal blocks for power, motors, relays, outdoor installs, or permanent wiring where tug resistance matters more than compactness. Plain headers are not the best choice for exposed wiring that will be pulled, vibrated, or left unprotected outside the enclosure.
Move to JST XH or another keyed/latching family when polarity protection and better retention matter. Just keep the pitch straight: 2.50mm JST XH is not 2.54mm header spacing.
IDC ribbon with a shrouded box header makes more sense when many signals need one keyed plug instead of a row of individual Dupont jumpers.
If the board already ships with populated headers, doing nothing may be the right answer. That is common on many Arduino boards and many Raspberry Pi boards, aside from headerless variants.
Machine-pin options are the step-up choice when repeated maintenance or cleaner repeated mating matters more than cost. The machine pin female header with half gold-plated contacts and the machine round-pin male header with press-fit insertion are the specialized options here.
“40 pin” does not always mean the same footprint: Raspberry Pi GPIO needs 2×20, not single-row 1×40.
Treat 2.54mm, 2.0mm, and 1.27mm as separate families even when the headers look almost identical in product photos. A 1x40 Male Header - 2mm Pitch will not replace a 1x40 Male Header - 2.54mm Pitch, and neither replaces a 1x40 Male Header - 1.27mm Pitch.
Standard through-hole headers require soldering for reliable electrical and mechanical connection. Simply pushing pins through the holes is not a dependable connection.
Male breakaway strips snap between pins. Female strips do not cut the same way and usually cost one sacrificed position when trimmed from a long strip.
Choose right-angle headers for side-entry layouts, not as automatic substitutes for straight headers in breadboards. A 1x40 Right Angle Male Header - 10mm Pin or 2x20 Right Angle Female Header solves cable direction, not every fit problem.
Breadboard compatibility depends on both 2.54mm pitch and enough usable pin length below the plastic, not pitch alone. That matters especially when you are choosing header stock for ESP32 boards or ESP8266 boards that arrive headerless or partially populated.
Measure the center-to-center distance between adjacent pins; breadboards, Arduino, and Raspberry Pi commonly use 2.54mm (0.1"), while 2mm and 1.27mm are separate non-interchangeable families. If the spacing is not exactly the same across the row, do not guess from photos or from total pin count.
Male headers go on boards when you need breadboard use or female Dupont jumpers, while female headers receive existing male pins. The default convention is male on the PCB and female on cables because it keeps the socket side on the replaceable wiring rather than on the board.
No — JST XH is 2.50mm and standard pin headers are 2.54mm. Very low pin counts may be forced, but the spacing error builds across the row and should not be treated as proper compatibility.
Only if the part still has enough usable pin length below the plastic; standard breadboard use expects 2.54mm pitch and about 6mm or more of pin length, while many right-angle parts are chosen instead for side-entry layouts. Check the pin-length detail, not just the pitch and the photo.
Standard through-hole headers need soldering for both electrical and mechanical connection. Pushing the pins through the holes without solder typically causes intermittent or no contact.
“40 pin” can mean single-row 1×40 or dual-row 2×20. Raspberry Pi GPIO specifically needs 2×20, while many generic breakaway strips are single-row 1×40.
Choose machine-pin headers when repeated maintenance, repeated mating, or cleaner premium socketing matters; the machine pin female option is half gold-plated, and the machine round-pin male option is gold-plated with press-fit insertion. Standard stamped square-pin strips remain the practical default for everyday breadboard and general PCB work.
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