How WillItSnap Checks Phone Case Compatibility: Our Methodology
By WillItSnap Team · March 15, 2026
Wondering whether your old phone case will fit a new phone? WillItSnap answers that question using real manufacturer data and a structured scoring algorithm. This page explains exactly how we do it — no black boxes, no guessing.
What WillItSnap Does
WillItSnap is a phone case compatibility checker. You pick two phones and we tell you whether a case designed for Phone A will fit Phone B. We analyze seven key factors that determine case fit and return a score from 0 to 100 along with a plain-English explanation of any issues.
Unlike generic “will it fit?” forums, we do not rely on user opinions. Every result is computed from the same set of dimensional and design data, so the answer is consistent and reproducible.
Our Data Sources
Accuracy starts with data. We source every measurement from official channels:
- Apple — Technical Specifications pages on apple.com for every iPhone, including height, width, thickness, weight, and camera module details.
- Samsung — Official spec sheets from samsung.com for Galaxy S-series, A-series, Z Fold, and Z Flip models.
- Google — Pixel phone specifications from the Google Store, including detailed camera bump measurements.
- OnePlus, Motorola, Xiaomi, Sony, and others — Manufacturer product pages and press kits with official dimensional data.
We never rely on third-party estimates or crowd-sourced measurements. When two sources disagree, we default to the manufacturer's own specification page.
The Scoring Algorithm (Plain English)
Our compatibility score starts at 100 (perfect fit) and subtracts points for every difference that would cause problems. Here are the seven checks, in order of importance:
1. Camera Layout Check
This is the single most important factor. If two phones have different camera module layouts — for example, a vertical dual-lens system vs. a horizontal camera bar — the case cutout simply will not line up with the cameras. When layouts differ, the result is instant incompatible (score 0). No amount of dimensional similarity can overcome a misaligned camera opening.
2. Width Check
Width is the most critical body dimension. A phone case wraps tightly around the left and right edges, so even a small width mismatch causes problems. If the phones differ by more than 0.5mm in width, the case either will not close around the wider phone or will be too loose on the narrower one. A difference of 0.3–0.5mm results in a moderate penalty for a slightly tight or loose fit.
3. Height Check
Height differences are more forgiving than width because the top and bottom of a case are less constrained. However, a height difference greater than 1mmmeans the phone will stick out or rattle inside the case. Between 0.5mm and 1mm, we flag it as a tight or loose fit with a moderate penalty.
4. Thickness Check
Thickness affects how snugly the phone sits in the case. A difference greater than 0.5mm in thickness means the case will feel noticeably loose or tight. This is less severe than width or height mismatches but still degrades the overall fit.
5. Camera Bump Size
Even when two phones share the same camera layout, the bump itself can differ in size. If the camera bump height or width differs by more than 2mm, the case cutout will be too small (blocking the lens) or too large (leaving the camera unprotected). Differences of 1–2mm receive a smaller penalty.
6. Button Positions
Phone cases have cutouts or raised overlays for the volume buttons, power button, action button, and camera control. If two phones have different button layouts — for example, the iPhone 15 Pro introduced an Action Button where the mute switch used to be — the case cutouts will not align. This incurs a moderate penalty.
7. Port Type
The bottom of a case has a cutout shaped for the charging port. If one phone uses Lightning and the other uses USB-C, or if one uses USB-C and the other has no port at all, the bottom cutout will not match. This carries a smaller penalty because some cases use oversized port cutouts, but it still affects fit.
What the Scores Mean
After running all seven checks, the remaining score maps to one of three outcomes:
Perfect Fit
The case will work with no issues. Dimensions, camera cutout, buttons, and port all align properly. You can confidently reuse this case.
Partial Fit
The case may physically go on, but expect problems: slightly misaligned buttons, a loose or tight feel, or a camera cutout that does not perfectly frame the lenses. We recommend buying a dedicated case.
Won't Fit
The case will not work. Major differences in dimensions, camera layout, or button placement prevent a usable fit. Do not force it — you risk scratching your phone or blocking the camera.
Our Coverage
WillItSnap's database is growing constantly. Here is where we stand today:
171
Phone Models
7,516
Compatibility Pairs
13
Brands
We cover phones from Apple, Samsung, Google, OnePlus, Motorola, and 10 more manufacturers. New models are added within days of official announcement.
Why We're Better Than Guessing
Most people check Reddit threads or Amazon Q&A sections when they want to know if a case fits. The problem? Those answers are anecdotal, often outdated, and rarely account for all the factors that matter.
- Dimension data is precise. We compare measurements to the tenth of a millimeter, not “it looks about the same size.”
- Camera layout is the #1 factor people miss. Two phones can be within 0.2mm of each other in every body dimension and still be completely incompatible because the camera module moved from a vertical stack to a diagonal arrangement.
- Button changes are invisible in photos. You cannot tell from a product listing whether a case has an Action Button cutout or a mute switch slot. Our data knows.
- Results are instant and free. No waiting for someone to reply to your post. Pick two phones and get a score in under a second.
Try WillItSnap Now
Pick any two phones and get an instant compatibility score with a detailed breakdown of every factor.
Check Case Compatibility →Explore More
Frequently Asked Questions
How accurate is WillItSnap's compatibility checker?▼
Our compatibility scores are based on official manufacturer dimensions measured to 0.1mm precision. We cross-reference height, width, thickness, camera layout, button positions, and port type. While no automated tool can replace physically testing a case, our algorithm catches the dimensional and design differences that cause the vast majority of fit failures.
Where does WillItSnap get its phone dimension data?▼
We source all dimensions from official manufacturer specification pages — Apple, Samsung, Google, OnePlus, Motorola, and other OEMs publish exact measurements for every phone model. We verify these against trusted tech databases and update our records when manufacturers issue corrections.
Why does camera layout matter more than phone size for case fit?▼
Phone cases have a precisely cut opening for the camera module. If two phones have different camera layouts (e.g., vertical dual vs horizontal bar), the cutout simply will not align — no matter how similar the body dimensions are. That is why our algorithm treats a camera layout mismatch as an instant incompatible result.
How often is the WillItSnap database updated?▼
Our database currently covers 171 phone models across 13 brands with 7516 pre-computed compatibility pairs. We add new phones within days of their official announcement and update existing entries whenever manufacturers revise specifications.