Bed leveling problems: uneven first layers across the plate

This guide is for anyone whose first layer looks good on one side of the plate and bad on the other. It explains how to tell an uneven bed from a Z-offset problem, how leveling works on Prusa, Bambu Lab and Creality printers, the steps each maker documents for specific models, what to check for warped or badly seated plates, and when to contact support. If the whole first layer won't stick, see our first layer adhesion guide.

Uneven bed or Z offset?

Two different settings control the first layer. Simplify3D separates them: first make sure the bed is level, because otherwise "one side of your bed may be too close to the nozzle, while the other side is too far away." Once the bed is level, "you still need to make sure that the nozzle is starting at the correct height relative to the build platform."

Prusa's Bed Level Correction article shows the uneven pattern: on a single-layer test print, the lines are "way too squished" in one corner while "the nozzle is too far away" in the opposite one. Creality's Ender-3 V3 SE troubleshooting page draws the same line between the two problems. When the first layer doesn't stick or the nozzle scrapes everywhere, it points to the Z-axis compensation value. When it happens "in specific area," it points to an X-axis assembly offset or a deformed hot bed or slide plate.

Polymaker explains why getting the height right matters at both ends. Too far and "your part won't stick and will be knocked off mid print." Too close and the first layer is "smashed out" into elephant's foot.

Step 1: Clean, seat and check the plate

Do this before changing any settings. Leveling and probing can only be as good as the surface they measure.

• Nothing under the plate. Prusa says to make sure there are "no leftovers from the previous print or a piece of loose filament that could affect the sheet position," and that the sheet is "straight and not bent or damaged." Its Bed Level Correction article says to make sure there is nothing between the steel sheet and the heatbed.
• Clean nozzle. Prusa (MK2/S, MK2.5/S and MK3/S/+) says debris on the nozzle can push the bed down during probing and force the printer to re-run mesh bed leveling. Bambu's tramming guides for the X1/P1 series and the A1 start by making sure the nozzle tip is free of filament. Creality's Ender-3 V3 SE page says to check for residue on the nozzle and platform, "especially the lower left corner of the platform."
• Same plate as last time. Bambu Lab (A1 series) says it's crucial to run bed leveling "particularly when changing or replacing the build plate," because skipping it may leave data that doesn't match the new plate.

Step 2: Let the printer level itself

Prusa: mesh bed leveling and the LoadCell

Prusa's printers use a sensor to measure the distance to the sheet at a grid of points and build "a virtual mesh of the bed." Prusa says that if the bed "is slightly warped, the sensor will still precisely follow the surface." The sensor depends on the model:

• CORE One, MK4/S, MK3.9/S and XL: a LoadCell, which Prusa says calibrates the first layer automatically. Before each print, the nozzle checks the distance in several places within the area of the chosen print.
• MINI and MINI+: the MINI has a M.I.N.D.A. sensor and the MINI+ a SuperPINDA. The grid is 4x4.
• MK3S+ and MK3.5/S: a SuperPINDA. Earlier models up to the MK3S use a PINDA. On the MK2.5/S and MK3/S/+ (firmware 3.7.0 and later), the mesh can be raised from the default 3x3 to 7x7 (49 points) under Settings, Mesh bed leveling, if the first layer is still uneven. Prusa suggests leaving Magnet compensation on.

If you have repeated first layer problems on a LoadCell printer (CORE One, MK4/S, MK3.9, XL), Prusa says to check the filament isn't being pulled down during leveling, loosen the spool a little, make sure any feed tube isn't too short, and run the Loadcell test from Control, Calibrations & tests. On the CORE One, MK4/S, MK3.9/S and MK3.5/S, it also says expansion joints in the wrong orientation can cause an uneven first layer.

Bambu Lab: auto bed leveling

Bambu Lab's guides treat auto bed leveling as the first step. For the A1 series, Bambu recommends turning on the Bed Leveling option in the slicer before you print, especially after changing or replacing the PEI plate. After manual tramming (X1/P1 series and A1), or after reseating the hotend on the A1 series, Bambu says to run calibration from the printer menu.

If bed leveling has run and the A1-series first layer is still too low, Bambu points to the hotend rather than the bed: retighten the heater assembly screws and check the heater assembly buckle is fastened, because a loose hotend "may shift downward during printing" and press the nozzle into the plate.

Creality: automatic leveling and Z offset

• Ender-3 V3 SE. For a first layer that doesn't stick or scrapes across the whole plate, Creality says the Z-axis compensation from automatic height detection deviates from the actual distance. It suggests adjusting the Z-axis compensation slightly while the first layer prints and updating to firmware 1.0.4 or later.
• Ender-3 S1. Creality's FAQ says that after CR Touch automatic leveling, you check the Z-axis compensation so the gap between nozzle and platform is "almost the thickness of a piece of A4 paper (0.08-0.1mm)."

Step 3: Fine-tune the first layer

Leveling handles tilt and warp. Height is still yours to tune.

• Prusa LoadCell printers (CORE One, MK4/S, MK3.9/S, XL): long-press the knob while the first layer prints to fine-tune. Prusa says this adjustment "will not be saved for the next print." For a lasting change, set Z offset in PrusaSlicer under Printers, General, where a negative value squashes the first layer more.
• Prusa printers with a PINDA, SuperPINDA or M.I.N.D.A. sensor: use Live Adjust Z, which is saved permanently. In its first layer issues article (MK2/S to MK3.5/S), Prusa warns not to compensate for poor adhesion by lowering it too far: the nozzle can damage the steel sheet, and damage from an incorrect Live Adjust Z value isn't covered by the warranty.
• Simplify3D: its Z-axis G-code offset moves the nozzle in fine steps, for example 0.05 mm. Simplify3D says "a small adjustment goes a long way" because a layer is usually only about 0.2 mm.

Correcting one side (Prusa MINI, MK3 and MK3.5 families)

If one side stays too high or too low after mesh leveling, Prusa's Bed Level Correction lets you set a different offset for the left, right, front and rear of the bed. Prusa says the limit is plus or minus 100 microns, that even 20 microns "can make a huge difference," and suggests steps of 10. Negative values bring the nozzle closer. Print Prusa's single-layer test model, adjust left and right first, test again, then front and rear. The values reset whenever you run the Calibration Wizard, XYZ calibration or XY axes test, so write them down. Prusa's Bed Level Correction article is listed for the MINI, MK3 and MK3.5 families, not the MK4, CORE One or XL.

A temporary offset (Bambu A1 series)

For the A1 series, Bambu describes changing the G29.1 offset in the printer start G-code as "only for a quick temporary fix" that "may introduce new local defects elsewhere." It recommends restoring the default once the root cause is fixed. Treat this as a last resort and follow Bambu's article exactly.

Step 4: Manual tramming, only where the maker calls for it

Bambu Lab X1 and P1 series

Bambu says the X1/P1 series ships with the bed correctly trammed, and the manual procedure "should be done only if you notice an inaccuracy in the bed leveling, or if asked by the customer service team." It sets each leveling knob flush as a baseline, then prints a G-code file from Bambu's article that moves the nozzle to each knob and pauses. You turn the knob until the surface "barely touches the nozzle," with no gap and no pressure. Tightening the nut moves the bed away from the nozzle. The routine runs three passes, then you run calibration (Utilities, Calibrate on the X1; Settings, Calibration on the P1).

Bambu Lab A1

Bambu says the A1's bed is calibrated at the factory. Tramming is for when transport has affected the bed and auto-leveling fails, or after the heatbed is removed or replaced. You loosen the two locking screws, set the three leveling screws, and run Bambu's G-code, adjusting each screw until the surface barely touches the nozzle (a sheet of paper can help judge the gap). Tightening a screw clockwise moves the bed away from the nozzle. The run takes about 8 minutes. Afterwards, tighten the two locking screws and run calibration from Settings, Maintenance, Calibration. Bambu's article includes a reset sequence if you can't get the surface to touch.

Creality Ender-3 S1 (CR Touch)

Creality's FAQ says automatic leveling isn't enough when "the inclination of the whole platform is greater than 2mm." Its auxiliary leveling sets the center height with Z-offset and A4 paper, then uses the knobs under the hot bed so the nozzle is the same height at all four corners. If the CR Touch is broken, Creality says the Z-axis limit switch has to be installed for manual leveling.

Manual-knob printers such as the original Ender-3

Creality's FAQ says automatic leveling on the original Ender-3 needs a BLTouch, bought separately. Without one, the bed is leveled by hand. Polymaker's general starting method for setting Z height is to home the printer, then change the height with a sheet of paper under the nozzle "until you get a minor amount of drag on the paper." On a knob-leveled bed, that means checking each corner and turning its knob, as Creality describes for the Ender-3 S1's manual leveling. Simplify3D includes a Bed Leveling Wizard under Tools that guides you through the same thing.

What if the plate or bed is warped?

• Slight warp is what probing is for. Prusa says its sensor follows a slightly warped bed using the measured mesh.
• Bent or damaged sheet. Prusa says to check the sheet is straight. If the surface isn't flat and the mesh doesn't help, Prusa's temporary fix is a piece of paper under the low area of the steel sheet, and its permanent fix is Bed Level Correction on supported models.
• Deformed bed or gantry (Ender-3 V3 SE). Creality lists X-axis assembly offset, hot bed deformation and slide plate deformation from transport as causes of problems in a specific area, and says to check each before adjusting the leveling data.
• Modular bed (Prusa XL). If one side is higher, Prusa says to check for loose screws holding the Core to the frame and under each heatbed tile.

If a plate is bent or its surface is damaged, a replacement is the fix. Check which surface suits the materials you print first. Our build plates shortlist and our guide to textured vs smooth build surfaces help with that.

When should you contact support?

• Bambu Lab (X1/P1 series and A1): if calibration after tramming still shows errors or warnings, Bambu says to contact its service team, and suggests a technical ticket with a picture or video.
• Creality (Ender-3 V3 SE): if the first layer is still wrong after checking the X-axis, hot bed and slide plate, Creality says to contact its after-sales service.
• Prusa: in its first layer issues article (MK2/S to MK3.5/S), Prusa says damage from an incorrect Live Adjust Z value isn't covered by warranty, so stop lowering it and look for the real cause. For sensor faults, Prusa has dedicated P.I.N.D.A./SuperPINDA and M.I.N.D.A. testing articles.

A sensible order

1. Decide whether the problem is one area (leveling) or everywhere (Z offset).
2. Clean the nozzle, clear under the plate and check the plate is flat and seated.
3. Run your printer's own leveling or calibration, especially after changing plates.
4. Fine-tune first layer height with your printer's live adjustment or slicer Z offset.
5. Use side-by-side correction or manual tramming only where your maker documents it for your model.
6. If problems stay in one area, check for a bent plate or deformed bed, then contact support.

Build plates: what to check before you buy ↗