FRC Robot Rules: Weight, Size, and Bumper Limits Explained

Every FRC robot has to live inside a box of rules before it ever touches a game piece. How heavy it can be, how big it can start, how far it can reach, and how its bumpers must be built - these constraints shape your entire design. Get them wrong and your robot fails inspection and never plays a match. Get them right and you have a safe, legal machine and the freedom to be creative inside the lines. This guide walks through each constraint, gives you the values from recent seasons so you know the ballpark, and - this is the important part - shows you why you must always confirm the exact numbers in the current season's Game Manual.

The one rule that beats all the others: check the current manual

Here is the single most important thing to understand before any number in this article: the robot construction limits change almost every season. FIRST publishes a new Game Manual each January, and Section 8, ROBOT Construction Rules (the "R" rules), is where weight, size, and bumper limits live. Those rules get revised game to game and even mid-season through Team Updates.

How much do they change? A lot. Compare just two recent seasons:

Same program, back-to-back years, and the size box shrank dramatically. That is exactly why you should treat every number below as "roughly this in recent seasons" and never as a permanent fact. Always open the current FIRST Game Manual and read Section 8 for yourself. Rule numbers like R103 or R405 are stable handles, but the values attached to them are not.

Weight: lighter than you think

In recent seasons the headline weight limit has been about 115 lb (~52 kg) for the robot excluding bumpers and excluding the battery. In the 2026 manual this is rule R103: "The ROBOT weight must not exceed 115.0 lb." (2026 also excludes the battery and the field location-detection tags from that figure.)

Two details trip up rookies:

• Bumpers and battery are weighed separately or excluded from the base limit. Recent manuals also cap the robot with bumpers - in 2026, rule R408 sets that at 135.0 lb (~61 kg). So your bumper set effectively gets its own ~20 lb budget on top of the robot.
• Some seasons add a total inspected weight for robots with swappable mechanisms. Always check whether the current game allows interchangeable parts and what the combined cap is.

Practical takeaway: weight is a budget you spend, not an afterthought. Heavy steel hardware, oversized gearboxes, and a tank-like superstructure add up fast. Teams that weigh subassemblies in CAD (Onshape reports mass automatically) almost never get a nasty surprise at the scale. Learn that workflow on our CAD design track.

Size and the frame perimeter

Your robot's footprint is governed by the frame perimeter (recent manuals call it the ROBOT PERIMETER - the name changed from FRAME PERIMETER in 2025). This is one of the most important concepts in the whole rulebook, so it's worth slowing down.

What the frame perimeter actually is

The frame perimeter is the outline formed by the fixed, non-articulated structural elements of your robot while it sits in its starting configuration, measured excluding bumpers. Crucially, it is the convex hull of those parts - imagine stretching a rubber band tightly around your robot's base. If you build a U-shaped frame, the perimeter is the rubber band that closes off the mouth of the U, turning it into a D. Concave notches do not count as "inside."

Tiny bumps don't count either: minor protrusions of 0.25 in or less - bolt heads, rivets, fastener ends, weld beads - are excluded from the perimeter. This is why your CAD team draws a clean perimeter sketch first and builds the frame to match it.

The size box

In recent seasons, the starting configuration has had two limits:

• A maximum perimeter length (the total distance around that rubber band) - 120 in in 2025 (R104), reduced to 110 in in 2026.
• A maximum starting height - 42 in in 2025, dropped to 30 in in 2026 (R104).

In the starting configuration, nothing may stick out past the vertical projection of the frame perimeter except the bumpers and those minor protrusions (in 2026 this is rule R102). In other words, at the start of the match your whole robot - arms folded, elevator down - must fit inside its own footprint.

Extension during the match

Once the match begins, most seasons let you reach beyond the frame perimeter, but only by a limited amount. Recent rules have capped horizontal extension at 18 in beyond the vertical projection of the perimeter in 2025, tightened to 12 in in 2026 (R105). There is also a height ceiling you may not exceed even when extended - 30 in throughout 2026 (R107).

Some games add their own extension twists (a single side that can extend, or no extension at all in certain zones), so the game-specific rules in Section 6 can override or layer on top of the general R rules. The design lesson: a mechanism that has to reach far horizontally - an intake, a scoring arm - must be planned around the current extension limit from day one. Our mechanical build track covers how to size linkages and elevators against these limits.

Bumpers: the rules people most often get wrong

Bumpers exist to protect robots from each other. They are mandatory, and inspectors scrutinize them hard. The bumper rules (the R4xx series in recent manuals) cover where bumpers sit, how they're built, how much they can stick out, and what color they are.

The bumper zone

Bumpers must fill the bumper zone, a horizontal band measured up from the floor. In 2025 and 2026 (R405) that zone has been 2.5 in to 5.75 in (~63 mm to ~146 mm) from the ground. Your backing and padding have to fully occupy that band so that two robots colliding hit padded bumper, not bare frame.

Construction: backing, padding, and cover

Recent manuals (rule R402) require, in essence:

• Rigid backing - traditionally a wood board such as plywood - tall enough to support the padding across the bumper zone (in 2026 the backing must be at least about 4.5 in tall).
• Soft padding in front of the backing. The 2026 rules require a minimum padding depth (about 2.25 in) and call out approved materials: solid pool noodle, backer rod, foam floor tiles, closed-cell polyethylene foam (including crosslinked), or closed-cell EVA foam. Note a real 2026 change - hollow pool noodles are no longer allowed; the foam must be solid or closed-cell.
• A cloth cover over the padding.

This is exactly the kind of detail that shifts. Always read the current R402 for the approved materials list and minimum dimensions before you cut anything.

How far bumpers stick out

Recent rules cap how far the hard parts of a bumper can extend from the frame perimeter at 1.25 in (~31 mm) (2026 R404), with the padding required to extend further beyond any hard part - at least 2.0 in in 2026 - and an overall bumper-extension cap (4.0 in in 2026, R403). The point: the soft stuff, not the wood or bolts, should be what makes contact.

Coverage and corners

Bumpers must protect the entire frame perimeter (R401). Small gaps between segments are tolerated within limits - in 2026, gaps under about 1.25 in are allowed - and corners get special attention. Recent rules require corner joints to be filled with uncompressed padding extending a set distance from each corner (at least 2.25 in in 2026, R406), and limit how large any single gap can be while still protecting a minimum length of perimeter on each side of every corner (about 5 in per side in 2026, R401). Exposed corners are a classic inspection failure.

Alliance color and mounting

Two more durable requirements:

• Alliance color: every robot must be able to show red or blue bumpers to match its alliance for a given match (R411). Most teams build two swappable sets or reversible covers.
• Mounting: bumpers must be fixed relative to the frame perimeter (R409) and designed for quick install and removal so inspectors can weigh and check the robot - the manual's guidance has been that two people should be able to swap them in just a few minutes.

Designing inside the box

The teams that thrive treat these constraints as the first design input, not a final-week scramble. Sketch your frame perimeter in CAD before building, budget weight by subassembly, plan your reach against the extension limit, and build bumpers to spec the first time. Read the FIRST Game Manual Section 8 every season, follow the Team Updates, and confirm every number - because as you've seen, they really do change.

Ready to start building a legal, competitive frame and bumper set? Dive into our mechanical build track.