Type a size, pick a fit, read the limits — H7/g6 sliding to H7/s6 press, 1–250 mm, per ISO 286. Real HTML tables (not screenshots), a free PDF, and the machining notes the textbook leaves out. Jump to:
Compiled and reviewed by the EKINSUN engineering team — an ISO 9001:2015 certified precision machining manufacturer. Tolerance values per ISO 286-2. Fits shown are hole-basis preferred fits; verify critical fits against your assembly spec. Last reviewed 17 Jul 2026.
// Fit Calculator — nominal size · hole · shaft
CLEARANCE FIT — sliding
Hole-basis system, ISO 286-2 values, sizes 1–250 mm. s6 offered to 50 mm — above that, drive fits split sub-ranges: ask us. Limits in mm; fit range in µm (positive = clearance, negative = interference).
Three parts: the nominal size (25 mm), the hole tolerance (capital letter + grade: H7 = bore at 25.000/+0.021), and the shaft tolerance (lowercase: g6 = shaft at 24.993/−0.013 below nominal). The letter sets where the tolerance zone sits relative to nominal; the number (IT grade) sets how wide it is. Because the H hole always starts exactly at nominal and shaft families range from loose (d) to heavy interference (s), one standard H7 bore can produce every fit type just by changing the shaft grade — which is why hole basis is the industry default and the system this page uses.
These eight hole-basis combinations cover almost every job we machine. The example column is computed at Ø25 mm — use the calculator above for your exact size.
| Fit | Type | Typical use | Example at Ø25 mm |
|---|---|---|---|
| H9/d9 | Loose running | Very free rotation, dirt-tolerant — agricultural shafts, loose pulleys | clearance +65 to +169 µm |
| H8/f7 | Close running | General rotating shafts in plain bushings, gearbox shafts | clearance +20 to +74 µm |
| H7/g6 | Sliding | Accurate sliding and guiding — spool valves, sliding gears, guide pins | clearance +7 to +41 µm |
| H7/h6 | Locational clearance | Parts that assemble by hand and stay put — spigots, locating rings | clearance +0 to +34 µm |
| H7/k6 | Locational transition | Snug, light press — pulleys, gears keyed to shafts, bearing seats | 15 µm interference to 19 µm clearance |
| H7/n6 | Transition (tight) | Rigid location, press assembled, transmits light loads with a key | 28 µm interference to 6 µm clearance |
| H7/p6 | Locational interference | True press fit — bushings into housings, bearing rings | interference 1 to 35 µm |
| H7/s6 | Medium drive (≤50 mm) | Permanent assembly, transmits torque by friction — press + heat | interference 14 to 48 µm |
These tables assume both parts are metal. Press a plastic bush into a steel housing and the interference does not stay in the joint: the bore closes by very nearly the whole of it, because a thin plastic wall has nowhere to put the material. The bush is either bored after pressing or cut oversize by the interference, and the running clearance starts from 0.3–0.5 % of shaft diameter rather than from an ISO fit class — see plastic bushings and plain bearings.
The shaft's largest allowed diameter is still below the hole's smallest. Motion is guaranteed; the question is how much play you can accept. On sliding spool valves and guide pins we machine to H7/g6; for rotating shafts in bronze or POM bushings, H8/f7 leaves room for an oil film. A typical build we see weekly: a hardened 304 stainless pin sliding in a bored 6061 housing — free after anodizing because we allowed for the coating growth up front.
H7/k6 and H7/n6 straddle the line: depending on where each part lands inside its tolerance, you get a light press or a snug slip. That's the point — near-zero play for accurate location, but still assemblable with a mallet and removable for service. Bearing seats and keyed pulleys live here. If your assembly must never loosen under vibration, step up to interference rather than hoping k6 lands tight.
H7/p6 presses a bushing into a housing so it stays put; H7/s6 transmits real torque by friction alone. Practical machining notes: interference values assume similar materials — pressing steel into a 7075 aluminum housing needs less interference than steel-into-steel because aluminum yields first, and thin-wall bushings can close their bore when pressed, so we verify the installed ID, not just the free-state ID. This is the detail that separates a chart from a part that works.
The IT grade is the total tolerance width in micrometres for a given size range — IT6 is precision grinding territory, IT7 a reamed or precision-bored hole, IT9 routine turning, IT11 rough work. Values per ISO 286:
| Grade | >1–3 | >3–6 | >6–10 | >10–18 | >18–30 | >30–50 | >50–80 | >80–120 | >120–180 | >180–250 |
|---|---|---|---|---|---|---|---|---|---|---|
| IT6 | 6 | 8 | 9 | 11 | 13 | 16 | 19 | 22 | 25 | 29 |
| IT7 | 10 | 12 | 15 | 18 | 21 | 25 | 30 | 35 | 40 | 46 |
| IT8 | 14 | 18 | 22 | 27 | 33 | 39 | 46 | 54 | 63 | 72 |
| IT9 | 25 | 30 | 36 | 43 | 52 | 62 | 74 | 87 | 100 | 115 |
| IT11 | 60 | 75 | 90 | 110 | 130 | 160 | 190 | 220 | 250 | 290 |
The three fits that cover most work, worked out in millimetres for the sizes people actually ask about. Hole is H7 in every row; pick the shaft that gives the behaviour you need. Values follow from the ISO 286 deviation tables further down this page.
Need a shaft or bore machined to one of these H7 / g6 / h6 / p6 fits? Any row is made to order from 1 piece, standard sizes can also be supplied from stock, quote in 12 hours, delivered DDP. Get a price on WhatsApp · Quote form
| Nominal | H7 bore (mm) | g6 shaft — sliding | Clearance | h6 shaft — locational | p6 shaft — press | Interference |
|---|---|---|---|---|---|---|
| Ø6 | 6.000–6.012 | 5.988–5.996 | 4–24 µm | 5.992–6.000 | 6.012–6.020 | 0–20 µm |
| Ø8 | 8.000–8.015 | 7.986–7.995 | 5–29 µm | 7.991–8.000 | 8.015–8.024 | 0–24 µm |
| Ø10 | 10.000–10.015 | 9.986–9.995 | 5–29 µm | 9.991–10.000 | 10.015–10.024 | 0–24 µm |
| Ø12 | 12.000–12.018 | 11.983–11.994 | 6–35 µm | 11.989–12.000 | 12.018–12.029 | 0–29 µm |
| Ø16 | 16.000–16.018 | 15.983–15.994 | 6–35 µm | 15.989–16.000 | 16.018–16.029 | 0–29 µm |
| Ø20 | 20.000–20.021 | 19.980–19.993 | 7–41 µm | 19.987–20.000 | 20.022–20.035 | 1–35 µm |
| Ø25 | 25.000–25.021 | 24.980–24.993 | 7–41 µm | 24.987–25.000 | 25.022–25.035 | 1–35 µm |
| Ø30 | 30.000–30.021 | 29.980–29.993 | 7–41 µm | 29.987–30.000 | 30.022–30.035 | 1–35 µm |
| Ø40 | 40.000–40.025 | 39.975–39.991 | 9–50 µm | 39.984–40.000 | 40.026–40.042 | 1–42 µm |
| Ø50 | 50.000–50.025 | 49.975–49.991 | 9–50 µm | 49.984–50.000 | 50.026–50.042 | 1–42 µm |
A fit is only half the specification — the surface it runs on is the other half. A sliding pair calculated at 7 µm of clearance will not behave as calculated if the shaft is left rough, so the surface roughness chart gives the Ra that belongs with each of these fits.
Reading a row: at Ø20, an H7 bore measures 20.000 to 20.021 mm. A g6 shaft at 19.980–19.993 leaves 7 to 41 µm of clearance and slides freely; an h6 shaft at 19.987–20.000 assembles by hand with no perceptible shake; a p6 shaft at 20.022–20.035 has to be pressed in and holds 1 to 35 µm of interference. Nothing here is a size we cannot cut — EKINSUN machines shafts, bores and bushings to any of these fits from one piece.
A fit is only meaningful once both halves exist. EKINSUN LTD is a custom parts manufacturer in Guangdong, China and machines shafts, bores, bushings and pins to these ISO 286 fits on request: state the fit rather than a bare dimension and the mating pair is cut to match. From one piece, quote within 12 hours.
| Situation | In the table? | How we handle it |
|---|---|---|
| A standard shaft or bush in a catalogue size and fit | Yes — buy it | A bearing or bush distributor will be cheaper, and the tolerance is already held. Honest recommendation. Standard parts: ask us too — we may have them in stock. |
| The bore is already worn oversize and cannot be re-machined | No — the table assumes nominal | Bore measured as it actually is, and the shaft or bushing turned to that real dimension, keeping the fit you specified |
| A fit on one section only — h6 at the bearing seat, general tolerance elsewhere | Configurators apply one tolerance to the whole part | Machined section by section, so precision is paid for only where it works |
| Aluminium housing, steel shaft, wide temperature range | ISO 286 is stated at 20 °C | Fit chosen for the hot condition — the difference in thermal expansion can consume the whole clearance |
| A press fit that must still be removable | H7/p6 is the value, not the method | Extraction thread, jacking flats or a shouldered puller face designed into the part |
| An imperial shaft into a metric bore, or the reverse | Two different systems, no single table | Each feature cut and gauged to its own standard on the same part |
A fit is written as two classes, but engineers look them up one at a time — “what does f7 mean” is asked far more often than “what is H8/f7”. Each class below is given at two reference sizes with the deviations in micrometres and the finished dimensions in millimetres, then the fit it normally forms. Values are ISO 286-2 for the hole-basis system; use the calculator above for any other size.
H7 is the hole tolerance class of the hole-basis system in ISO 286, always starting at the nominal size: a Ø25 mm H7 hole is +21 to 0 µm, so it measures 25.000–25.021 mm; a Ø50 mm H7 hole is +25 to 0 µm, 50.000–50.025 mm. The shaft grade then decides the fit: g6 gives a sliding fit, h6 a locational clearance, k6 a light press and p6 a true press fit, all with the same H7 bore.
H8 is the hole tolerance class of the hole-basis system in ISO 286, always starting at the nominal size: a Ø25 mm H8 hole is +33 to 0 µm, so it measures 25.000–25.033 mm; a Ø50 mm H8 hole is +39 to 0 µm, 50.000–50.039 mm. H8 is one grade coarser than H7 and is the standard partner of an f7 shaft in the close-running fit H8/f7; it is the tolerance a reamed or bored bushing seat usually carries when the shaft, not the hole, controls the fit.
f7 is a clearance shaft tolerance class in ISO 286: for a Ø25 mm shaft (18–30 mm range) f7 means -20 to -41 µm, so the shaft measures 24.959–24.980 mm; for a Ø50 mm shaft (30–50 mm range) it is -25 to -50 µm. Paired with an H8 hole it gives the close-running fit H8/f7 — 20 to 74 µm clearance at Ø25 — used for shafts turning in plain bushings and gearbox shafts.
g6 is a clearance shaft tolerance class in ISO 286: for a Ø25 mm shaft (18–30 mm range) g6 means -7 to -20 µm, so the shaft measures 24.980–24.993 mm; for a Ø50 mm shaft (30–50 mm range) it is -9 to -25 µm. Paired with an H7 hole it gives the sliding fit H7/g6 — 7 to 41 µm clearance at Ø25 — used for guide pins, spool valves and gears that slide on a shaft.
h6 is a clearance shaft tolerance class in ISO 286: for a Ø25 mm shaft (18–30 mm range) h6 means 0 to -13 µm, so the shaft measures 24.987–25.000 mm; for a Ø50 mm shaft (30–50 mm range) it is 0 to -16 µm. Paired with an H7 hole it gives the locational clearance fit H7/h6 — 0 to 34 µm clearance at Ø25 — used for spigots and locating rings assembled by hand.
k6 is a transition shaft tolerance class in ISO 286: for a Ø25 mm shaft (18–30 mm range) k6 means +15 to +2 µm, so the shaft measures 25.002–25.015 mm; for a Ø50 mm shaft (30–50 mm range) it is +18 to +2 µm. Paired with an H7 hole it gives the locational transition fit H7/k6 — 15 µm interference to 19 µm clearance at Ø25 — used for pulleys, keyed gears and bearing seats that need a light press.
n6 is a transition shaft tolerance class in ISO 286: for a Ø25 mm shaft (18–30 mm range) n6 means +28 to +15 µm, so the shaft measures 25.015–25.028 mm; for a Ø50 mm shaft (30–50 mm range) it is +33 to +17 µm. Paired with an H7 hole it gives the tight transition fit H7/n6 — 28 µm interference to 6 µm clearance at Ø25 — used for rigid location pressed together, torque carried by a key.
p6 is a interference shaft tolerance class in ISO 286: for a Ø25 mm shaft (18–30 mm range) p6 means +35 to +22 µm, so the shaft measures 25.022–25.035 mm; for a Ø50 mm shaft (30–50 mm range) it is +42 to +26 µm. Paired with an H7 hole it gives the press fit H7/p6 — 1 to 35 µm interference at Ø25 — used for bushings into housings and bearing rings.
A tolerance class is a promise about a machined surface, and it is only as good as the machine and the measurement behind it. EKINSUN LTD is a custom parts manufacturer and works to these classes daily: shafts turned to g6, h6 or k6 from a sketch, bushings and spacers bored to H7, dowel and locating pins to m6, and keyed shafts where the h6 seat and the N9 keyway are cut in one set-up. When the drawing is gone, the worn part is measured to find which class it was made to and the new one is machined to it — MOQ 1, quote in 12 hours.
H holes are the easy ones: lower limit = nominal exactly, upper limit = nominal + IT grade. Cells show ES over EI in µm:
Need a bore machined to one of these hole tolerances? Any row is made to order from 1 piece, standard sizes can also be supplied from stock, quote in 12 hours, delivered DDP. Get a price on WhatsApp · Quote form
| Hole | >1–3 | >3–6 | >6–10 | >10–18 | >18–30 | >30–50 | >50–80 | >80–120 | >120–180 | >180–250 |
|---|---|---|---|---|---|---|---|---|---|---|
| H7 | +10 0 | +12 0 | +15 0 | +18 0 | +21 0 | +25 0 | +30 0 | +35 0 | +40 0 | +46 0 |
| H8 | +14 0 | +18 0 | +22 0 | +27 0 | +33 0 | +39 0 | +46 0 | +54 0 | +63 0 | +72 0 |
| H9 | +25 0 | +30 0 | +36 0 | +43 0 | +52 0 | +62 0 | +74 0 | +87 0 | +100 0 | +115 0 |
| H11 | +60 0 | +75 0 | +90 0 | +110 0 | +130 0 | +160 0 | +190 0 | +220 0 | +250 0 | +290 0 |
Cells show upper deviation (es) over lower deviation (ei) in µm. Negative = below nominal (clearance families d–h), positive = above nominal (transition and interference grades k6–s6):
Need a shaft machined to one of these shaft tolerances? Any row is made to order from 1 piece, standard sizes can also be supplied from stock, quote in 12 hours, delivered DDP. Get a price on WhatsApp · Quote form
| Shaft | >1–3 | >3–6 | >6–10 | >10–18 | >18–30 | >30–50 | >50–80 | >80–120 | >120–180 | >180–250 |
|---|---|---|---|---|---|---|---|---|---|---|
| d9 | -20 -45 | -30 -60 | -40 -76 | -50 -93 | -65 -117 | -80 -142 | -100 -174 | -120 -207 | -145 -245 | -170 -285 |
| e8 | -14 -28 | -20 -38 | -25 -47 | -32 -59 | -40 -73 | -50 -89 | -60 -106 | -72 -126 | -85 -148 | -100 -172 |
| f7 | -6 -16 | -10 -22 | -13 -28 | -16 -34 | -20 -41 | -25 -50 | -30 -60 | -36 -71 | -43 -83 | -50 -96 |
| g6 | -2 -8 | -4 -12 | -5 -14 | -6 -17 | -7 -20 | -9 -25 | -10 -29 | -12 -34 | -14 -39 | -15 -44 |
| h6 | +0 -6 | +0 -8 | +0 -9 | +0 -11 | +0 -13 | +0 -16 | +0 -19 | +0 -22 | +0 -25 | +0 -29 |
| h7 | +0 -10 | +0 -12 | +0 -15 | +0 -18 | +0 -21 | +0 -25 | +0 -30 | +0 -35 | +0 -40 | +0 -46 |
| h9 | +0 -25 | +0 -30 | +0 -36 | +0 -43 | +0 -52 | +0 -62 | +0 -74 | +0 -87 | +0 -100 | +0 -115 |
| h11 | +0 -60 | +0 -75 | +0 -90 | +0 -110 | +0 -130 | +0 -160 | +0 -190 | +0 -220 | +0 -250 | +0 -290 |
| k6 | +6 +0 | +9 +1 | +10 +1 | +12 +1 | +15 +2 | +18 +2 | +21 +2 | +25 +3 | +28 +3 | +33 +4 |
| n6 | +10 +4 | +16 +8 | +19 +10 | +23 +12 | +28 +15 | +33 +17 | +39 +20 | +45 +23 | +52 +27 | +60 +31 |
| p6 | +12 +6 | +20 +12 | +24 +15 | +29 +18 | +35 +22 | +42 +26 | +51 +32 | +59 +37 | +68 +43 | +79 +50 |
| s6 | +20 +14 | +27 +19 | +32 +23 | +39 +28 | +48 +35 | +59 +43 | — | — | — | — |
A tolerance chart tells you the target; holding it is process. H7 bores under Ø20 we ream; larger ones we single-point bore and measure with three-point mics. Precision shafts to g6/h6 come off CNC turning with in-process gauging, ground where the drawing demands it. Every toleranced feature can ship with a dimensional report from our inspection department — and if your part is a worn shaft or a bushing with no drawing at all, reverse engineering recovers the original fit before we machine the replacement. The parts these fits live on are exactly what we build daily: custom shafts, spacers and bushings, and press-fit components — even without CAD.
Fit trouble on an existing assembly? Send the mating part or its measurements. We'll machine the new component to restore the original fit — sliding, located or pressed — with the fit class stated on the quote so you know exactly what you're getting. MOQ 1. For torque specs on the fasteners holding it together, see our metric bolt torque chart.
When this table stops being enough: The numbers above assume both parts are still nominal. Four situations break that, and they are the ones that reach us: the mating part already exists and is worn oval, so 25 mm is no longer 25 mm and the fit has to be cut to the bore that is actually there; a shaft sits in a housing with no drawing, so the fit must be derived from the housing rather than looked up; steel is being fitted into an aluminium housing, where aluminium expands roughly twice as much and a clean H7/s6 at 20 °C is a different fit at 90 °C; and anything tighter than IT6, which leaves turning territory and needs grinding plus a measurement record. In all four the standard does not decide the number - measuring the real part does. We machine the part that the table cannot describe — we measure your sample and turn the counterpart, obsolete parts with no drawing, or a shaft cut to a housing you already have. From one piece, quoted within 12 hours.
In a plate, H7 is the usual fit for reamed dowel holes and for the spigot recess that centres a motor pilot, because a bolt in a 9 mm clearance hole can still shift by 1 mm on an M8; plates that locate parts this way are on adapter and mounting plates.
A bearing seated to H7 or k6 is usually held axially by a circlip; the DIN 471 and DIN 472 groove sizes for shaft and bore are in the circlip groove size chart.
A hole whose lower limit sits exactly on nominal, IT7 wide. A 25 H7 bore measures 25.000–25.021 mm. It's the standard precision bore because it pairs with g6, h6, k6 or p6 shafts to make any fit type.
Capitals are holes, lowercase are shafts. 25 H7 = 25.000/+0.021 bore; 25 h7 = 25.000/−0.021 shaft. Swapping them on a drawing reverses the fit.
H7/g6 — at Ø25 it gives 7–41 µm clearance: smooth travel, no perceptible shake. Faster rotation in bushings: H8/f7. Hand assembly with accurate location: H7/h6.
H7/p6 gives ~1–35 µm at Ø25 — a firm arbor-press fit for bushings and bearing rings. Torque-carrying drive fits (H7/s6, 14–48 µm) usually need heat or hydraulics to assemble.
Hole basis by default: holes come from fixed-size tools (reamers), shafts are easy to turn to any diameter. Shaft basis suits standard drawn shafting that must take several fits along one bar.
Yes — spec the fit (30 H7 bore, 30 g6 shaft) or describe what the joint must do and we'll choose it. Toleranced features measured, dimensional report available, MOQ 1 piece.
Case matters: capital H7 is a hole (25.000/+0.021), lowercase h7 is a shaft (25.000/−0.021). Both touch the nominal size but on opposite sides. Mixing them up on a drawing reverses the fit — a common and expensive mistake.
IT grades + hole & shaft deviation tables + preferred fits on one printable sheet.
Download PDF ↓Custom shafts, bushings and press-fit parts machined to the exact fit — from a drawing, sketch or the mating part itself.
Shafts, bushings and precision bores machined to H7/g6, H7/p6 or any fit you name — MOQ 1, quote in 12 hours.