--- title: Tolerance: What It Means on a Machining Drawing | Wolf Machine url: https://wolfmachinenv.com/glossary/tolerance/ business: Wolf Machine & Fabrication, Inc. address: 4812 Longley Ln, Reno, NV 89502 phone: (775) 359-5570 hours: Shop Monday-Friday 7:00 am-3:30 pm; closed Saturday and Sunday type: Metal and plastic fabrication and machining (custom and CNC machining, welding, metal and plastic fabrication, gearbox and part repair, align boring, metal spray) --- [Photo: Stock photo: measuring a turned brass shaft with a vernier caliper] - [Home](https://wolfmachinenv.com/) - [Glossary](https://wolfmachinenv.com/glossary/) - Tolerance # Tolerance A tolerance is the amount a size, position or form on a part is allowed to vary from the number on the drawing and still be acceptable. It is written next to the dimension, for example 2.000 +/- .005 inches, or set for the whole drawing in the title block. Stock photo: measuring a turned brass shaft with a vernier caliper No machine cuts a perfect number every time. The tolerance tells the machinist how close is close enough, and it tells the inspector what to accept. It is the single biggest thing on a drawing that decides how a part is made and what it costs. ## How tolerances are written A bilateral tolerance allows variation both ways: 1.500 +/- .002 means anything from 1.498 to 1.502 is good. A unilateral tolerance allows it one way only, common on shafts and bores that have to fit together. A limit dimension simply states the smallest and largest size, such as 1.498 / 1.502. Most drawings also carry a general tolerance block that covers any dimension without its own callout, often by the number of decimal places shown. Position, flatness, roundness and similar controls are written with [GD&T](https://wolfmachinenv.com/glossary/gd-and-t/) symbols under the ASME Y14.5 standard. ## Why tolerance drives cost Holding a tighter tolerance usually means slower cuts, more setups, finish passes, grinding or more inspection time. A tolerance that is tighter than the part needs adds cost without adding function. The best drawings put tight tolerances only where parts fit, seal or locate, and leave the rest open. When you send a print for a quote, the tolerances on it are part of what we price. If a size only has to clear another part, saying so can save money. ## Tolerance and fits When two parts go together, their tolerances combine into a fit: a clearance fit slides, an [interference fit](https://wolfmachinenv.com/glossary/interference-fit/) presses together. Bearing seats, bushings and pins depend on the right fit more than on any one number. ### Sources - [ASME Y14.5-2018, Dimensioning and Tolerancing](https://www.asme.org/codes-standards/find-codes-standards/y14-5-dimensioning-tolerancing) (2026-10-18) ### Talk to the shop [(775) 359-5570](tel:(775)%20359-5570) | Monday to Friday | 7:00 am - 3:30 pm | |---|---| | Saturday and Sunday | Closed | [Request a quote](#quote) ### Keep reading - [What to put on a drawing before you ask for a quote](https://wolfmachinenv.com/guides/what-to-put-on-a-drawing/) - [What makes a machined part expensive?](https://wolfmachinenv.com/faq/what-makes-a-machined-part-expensive/) - [Custom machining](https://wolfmachinenv.com/services/custom-machining/) ## See also [GD&T (geometric dimensioning and tolerancing)](https://wolfmachinenv.com/glossary/gd-and-t/) [Interference fit](https://wolfmachinenv.com/glossary/interference-fit/) [Surface finish (Ra)](https://wolfmachinenv.com/glossary/surface-finish-ra/) [Runout (TIR)](https://wolfmachinenv.com/glossary/runout-tir/) ## Where you will see it on this site [From one prototype to a production run](https://wolfmachinenv.com/blog/prototype-to-production-run/) [What makes a machined part expensive?](https://wolfmachinenv.com/faq/what-makes-a-machined-part-expensive/) [What to put on a drawing before you ask for a quote](https://wolfmachinenv.com/guides/what-to-put-on-a-drawing/) [Photo: Stock photo: a lathe turning a bar, hot chips flying] ## Request a quote Tell us what you need, attach a drawing or photos of the part, and we will get back to you during shop hours. Free consultations; prompt estimates. [Call (775) 359-5570](tel:(775)%20359-5570) - From your specifications, drawings or samples. We can also assist you in designing your product or part. - Free consultations and prompt estimates - Stands behind the work: Our rates are very competitive and our quality is second-to-none. Wolf Machine stands behind the work we perform. - Company accounts: all major credit cards, or we can open an account for your company Shop hours Monday to Friday, 7:00 am to 3:30 pm. Send your request any time and we will get back to you during shop hours. Stock photo: a lathe turning a bar, hot chips flying