Every Airless Tip Number Decoded: Orifice, Fan Width and the Coating It Was Built For
The first digit doubled is the fan width in inches at 12 in from the surface. The last two digits are the orifice in thousandths of an inch. A 517 is a 10 in fan through a 0.017 in hole; a 311 is a 6 in fan through 0.011. Fan width sets how fast you cover; orifice sets how much material and how much sprayer you need behind it.
By the Paint Desire Editorial Team
Take the first digit and double it — that is the fan width in inches, measured 12 in from the surface. Take the last two digits and read them as thousandths of an inch — that is the orifice. A 517 sprays a 10 in fan through a 0.017 in hole. A 311 sprays a 6 in fan through 0.011.
Those two numbers do different jobs and people constantly conflate them. Orifice decides how much material leaves the gun per second, what viscosity you can push, and how big a pump you need. Fan width decides how far that material gets spread — which is why a 411 and a 311 flow identically but lay very different film.
Every tip below was decoded on paper and then sprayed, so the rated fan width sits next to the width actually measured on a card at 12 in with real coating in the pump rather than water on a test bench.
Rated fan width and the fan you actually get
Manufacturers rate fan width with water, at around 2000 psi, at 12 in. Nobody sprays water. Put a full-bodied acrylic through the same tip at 2200 psi and the fan comes in narrower — commonly 1 to 2 in narrower on a 10 in tip.
Drop the pressure and it narrows further, then starts throwing tails: heavy fingers of unatomised material at the edges of the pattern. Tails are the airless equivalent of a starved HVLP fan and they are always the same message — not enough pressure for this orifice with this material.
Worn tips do the opposite in one dimension and the wrong thing in the other. The orifice erodes larger, so flow climbs, but the fan collapses inward. A tip that started at a measured 8.5 in and now reads 6 in is putting the same paint through a smaller footprint, which is why your walls suddenly need two passes and the edges keep running. That is the moment to bin it, not the moment to turn the pressure up.
The full tip table
Sessions ran on a 12 in card at 12 in standoff, gun square to the surface, steady travel at roughly 2 ft per second with a 50% overlap. Wet mils came off a comb gauge on a flat panel immediately after the pass. Minimum sprayer rating includes about 20-25% headroom over the tip's own flow demand, because a pump running at its rated maximum is a pump that will not hold pressure at the end of 100 ft of hose.
Tip Orifice (in) Rated fan at 12 in Measured fan at 12 in Built for Min sprayer rating (GPM) Wet mils per pass 208 0.008 4 in 3.5 in Dye, wiping stain, thin sealer 0.25 3.0 210 0.010 4 in 3.5 in Lacquer, sanding sealer, shellac 0.30 4.5 311 0.011 6 in 5.0 in Precat lacquer, thin enamel, trim work 0.30 3.5 313 0.013 6 in 5.5 in Oil enamel, conversion varnish, cabinet doors 0.38 4.5 411 0.011 8 in 6.5 in Stain and sealer over broad flat work 0.30 2.5 413 0.013 8 in 7.0 in Alkyd enamel, waterborne trim enamel 0.38 3.5 415 0.015 8 in 7.0 in Acrylic enamel, primer on doors and trim 0.50 4.5 515 0.015 10 in 8.5 in Interior latex, ceilings, light-bodied acrylic 0.50 3.5 517 0.017 10 in 8.5 in Interior and exterior latex — the default tip 0.60 4.5 519 0.019 10 in 9.0 in Heavy-bodied latex, exterior acrylic 0.75 5.5 521 0.021 10 in 9.0 in Drywall primer, high-solids acrylic 0.95 6.5 523 0.023 10 in 9.0 in Masonry acrylic, heavy exterior coatings 1.10 7.5 621 0.021 12 in 10.5 in Exterior siding acrylic over large runs 0.95 5.5 627 0.027 12 in 10.5 in Elastomeric, heavy-build waterproofers 1.50 7.5 631 0.031 12 in 11.0 in Block filler, thick elastomeric 2.00 9.0 Pick the orifice from the coating column first, then pick the fan width from the size of what you're spraying. Never pick a tip whose minimum sprayer rating exceeds your pump's rated GPM — it will not hold pressure and the fan will tail all day. Compare the 311 and the 411. Same orifice, same flow, same pump demand — but the 411 spreads it over 8 rated inches instead of 6, so it lays 2.5 wet mils where the 311 lays 3.5. If your enamel keeps running on stiles and rails, dropping from a 311 to a 411 fixes it without touching the pressure or the reduction.
Feeding the tip is the constraint most people miss
Airless flow is set almost entirely by orifice area, and area goes up with the square of the diameter. Step from 0.015 to 0.021 and you have not gone up 40% in flow — you have gone up roughly 95%. That is why a small portable rig that sprays beautifully with a 515 turns useless the moment somebody fits a 521.
A pump that cannot feed the tip announces it in a specific way: pressure sags mid-pass, the fan pulses, and the motor runs continuously instead of cycling. Painters usually respond by cranking the pressure knob to maximum, which just accelerates tip and packing wear while fixing nothing.
Small tips have the opposite failure. Put a 208 on a big commercial pump and the machine cycles hard against a near-closed orifice, which hammers the packings. Match the tip to the machine in both directions.
Fine-finish tips are a different family
Fine-finish, low-pressure tips — the FFLP and LP families and their equivalents from other makers — use a pre-orifice to atomise at 1000-1600 psi instead of 2000-2400. Same numbering convention. Same orifice math. Very different pressure window.
They matter on cabinet doors and trim because lower pressure means less overspray bounce and softer edges, and because a coating that atomises at 1200 psi is being sheared less violently on the way out. Waterborne enamels in particular hold their flow better through a fine-finish tip.
The catch: a fine-finish tip run at conventional pressure will spit and split the pattern. If you fit one, drop the pump down before you pull the trigger, not after.
Pressure windows by coating
Each row below is the band where the logged pattern stayed clean — no tails at the bottom, no visible fogging or excess bounce at the top. Width is the band in psi. Narrow bands need a pressure gauge you trust, not the printed dial on the knob.
Coating Tip used Pressure window (psi) Width Below window Above window Precat lacquer 311 fine-finish 900-1400 500 Tails at fan edges Dry spray, heavy fog Conversion varnish 313 fine-finish 1100-1600 500 Coarse droplets, texture Dry edge on verticals Waterborne trim enamel 413 fine-finish 1200-1800 600 Tails, poor flow-out Overspray, thin build Alkyd enamel 413 1300-1900 600 Fingers at the edges Excessive fog, wasted material Interior latex 517 1800-2400 600 Tails and heavy edges Fog, accelerated tip wear Exterior acrylic 519 2000-2600 600 Ropey pattern Fog and bounce-back Drywall primer 521 2200-2800 600 Skips and tails Fog, poor hide per gallon Elastomeric 627 2600-3200 600 Uneven ropey pattern Pump strain, packing wear Set the pressure at the bottom of the window and climb until the tails disappear, then stop. Every psi above that point is material on the floor and wear on the tip. Three tips cover most of the work
If you buy nothing else: a 515 for interior latex and ceilings, a 517 for everything exterior and for heavier interior coats, and a 413 fine-finish for doors, trim and cabinet fronts. That kit covers the overwhelming majority of residential work.
Add a 519 if you spray a lot of exterior acrylic on rough surfaces. Add a 311 fine-finish if you shoot lacquer or precat. Skip the 621 and above unless you actually run elastomeric or block filler, because they demand a pump most people do not own.
Buy tips in pairs when you can. Tip wear creeps up slowly enough that you will not notice it against yesterday's memory, but you will notice it instantly against a fresh one in the same session.
Logging your own tip windows
Every tip has a serviceable life measured in gallons, not months, and it depends heavily on what you push through it. Heavily pigmented coatings — masonry acrylics, block filler, high-solids exterior acrylics — erode a tip several times faster than clear-bodied enamels do.
The cheap way to track it is a card and a marker. Every time you fit a tip, spray a 12 in card at 12 in and mark the fan edges. Do it again every couple of jobs. When the marked width has dropped 20% from new, the tip is done, whatever the calendar says.
That one habit will save you more paint than any pressure adjustment you will ever make.