Trailing length of string pulled on last stretch before the knot
Leave blank to use full reel length
Reelizr helps tennis stringers and players get the most from their string reels by calculating optimal string lengths for maximum efficiency and cost savings.
How it works: Using ellipsis geometry equations derived from racquet head dimensions, Reelizr calculates exact mains and crosses lengths — accounting for string elasticity, pull length, and stringing method.
String lengths use the Reelizr method — optimized based on your specific racquet geometry.
Reelizr runs entirely in your browser — no account required. All your racquets, reels, settings, and job history are stored locally on your device using browser storage.
⚠ Important: Clearing your browser cache, cookies, or site data will permanently erase all your Reelizr data. This includes reel inventory, remaining string lengths, and job history.
To preserve your data — go to Settings → Export regularly and save the JSON backup file to a safe location such as cloud storage or email it to yourself.
To migrate to a new browser or device — export on your current browser, then open Reelizr on the new browser and use Settings → Import to restore everything exactly as it was.
In exchange for free access, Reelizr anonymously collects equipment details, stringing parameters, and job history — such as racquet models, string types, tensions, and cut lengths. This data contains no personal information and helps improve the app and understand how stringers work.
Add all tennis racquets you string. You can specify an owner name to manage racquets for multiple players.
For each racquet you need five values:
Tip: Head area, mains and crosses come from manufacturer spec sheets. Head length and width must be measured by yourself with a tape measure along the outer frame edge.
Add all string reels you use. For each reel you need 2 parameter values:
When the reel is brand new, remaining length = full reel length.
Set your defaults so the calculator is pre-filled for your most common jobs:
After the first calculation, the last used settings will be preserved for next string job.
Recommended Workflow:
The optimizer sweeps pull lengths from 8" to 24" and shows exactly how many sets you get from your remaining string at each pull length. Tap the BEST row in each section to select it, then tap Calculate at the bottom to apply.
Starting Clamp (8"–17"): Using a bridging or starting clamp lets you reduce the last pull to ~8"–17", saving ~1 ft per job on average and unlocking extra sets from your reel.
Standard Machine (18"–24"): Most machines need at least 18" of tail to tension safely. Pick the pull length in this range that maximizes your sets.
Two-piece jobs: Switch between the Mains and Crosses tabs to pick the optimal pull length independently for each string — they can differ since mains and crosses have different cut lengths.
Lengths account for racquet geometry and string elasticity. For a safety margin, select a stiffer material, lower tension, or thicker gauge — each gives a slightly longer calculated length.
Stringing Method Legend:
For one-piece stringing the midpoint shows where to mark the string before you start — string mains from this mark toward the handle.
Note: Even with a standard pull length, Reelizr lengths are already optimised and will yield extra sets vs. unoptimised cutting. The optimizer simply helps you squeeze out the maximum possible sets from every reel.