The Two Numbers Most 3D Print Sellers Are Ignoring (And Why Your Margin Is Lying to You)

Y'all, you're probably underpricing your prints. And it's not because of filament.

Most people I talk to in Discord track filament cost down to the gram. They weigh the spool, they know the cost per kilo, they multiply it out. And then they stop. Two costs never make it into the math — electricity and printer wear. Both of them get skipped because the math feels intimidating, and the result is that everyone selling prints quietly eats those costs without knowing it.

And if you've never thought about these two costs, that's okay. Most makers haven't. They don't show up on a spreadsheet, they don't show up on an invoice, and they don't show up in the weekend revenue total. They show up everywhere else. I'm gonna walk you through both.

Yeah, I know, math sucks. But the math here is honestly not bad. Two formulas, both straightforward, both worth the ten minutes it takes to learn them. I built these two fields into Margin Forge because I needed them. The first market where I ran Margin Forge end-to-end, I realized I'd been pricing prints like filament was the only input. It wasn't.

By the end of this article you'll know exactly what your power costs per print. You'll know how to think about printer wear. And you'll know how to plug both into Margin Forge so the margin number you see is the real margin.

What you need

Your most recent electricity bill (one minute, I'll show you where to look)

The price you paid for your printer

A rough sense of how many hours you expect to get out of it

A smart plug or Kill-A-Watt meter (optional, but really, really useful)

Why filament-only math is broken

If you're tracking nothing but filament, your "margin" is fiction. The math problem in one sentence: a $30 sale that uses $4 of filament looks like $26 of profit. Then you account for the $1 of electricity, the $1.50 of printer wear, the packaging, the labor, the booth fee. By the time the real numbers land, that $26 margin can be $15. Sometimes worse.

Filament is the bill you see. Electricity is the bill you don't open. Depreciation is the bill that arrives years from now in one chunk, when the hotend or board finally goes. All three are real. Only one of them is on your radar.

Hidden costs are the ones that wreck small businesses, because you never get to make the decision "is this print worth running?" — you already ran it. I want these two visible right now, before they become a surprise.

How to find your per-kWh rate

This takes one minute. Pull up your most recent electricity bill and look for a line that says one of these:

Cost per kWh

Energy charge per kWh

Rate with a unit of $/kWh

Most US bills land somewhere between $0.10 and $0.40 per kWh, depending on your state and utility. California and the Northeast trend higher. The Midwest and Southeast trend lower. Texas is its own world.

Two heads-up before you commit to a number:

Time-of-use plans.

If your utility charges different rates by time of day, get a number for the hours your printer runs. Mine runs overnight, so the off-peak rate is the one I plug in.

Tiered pricing.

Some utilities raise the rate after you cross a usage threshold for the month. Heavy users get billed at the top-tier rate, not the average. Use the highest tier you regularly hit.

If your bill is confusing or you can't find a clean per-kWh number, search "[your utility name] rate sheet." That's the document with every per-kWh number spelled out.

The electricity math

Two steps. Watts-to-kilowatts, then kilowatts-times-hours-times-rate.

Step 1: kWh used = (average watts × print hours) ÷ 1000

Step 2: Cost = kWh used × your $/kWh rate

That's it. Nothing else.

Most people use their printer's nameplate wattage — that big 350 W or 1000 W number on the back of the machine. That number is the maximum draw, the worst-case the power supply has to handle. It's the right number for sizing a fuse and the wrong number for cost math. Steady-state during a print is way, way lower. The heated bed and hotend cycle on and off after the warmup phase, and the average draw drops to a fraction of nameplate.

Here are the numbers the community has measured with Kill-A-Watts and smart plugs, posted in maker forums. Average draw during a typical PLA print, after warmup, no heated chamber:

Bambu Lab X1 Carbon: ~100–135 W

Bambu Lab P1S: ~30–70 W (the enclosure really, really helps)

Bambu Lab P1P: ~60 W (no enclosure, runs hotter than P1S)

Bambu Lab A1: ~95 W

Bambu Lab A1 mini: ~50–57 W (lowest steady-state in the lineup)

Prusa MK4 / MK4S: ~80–130 W

Prusa Core One: ~90 W on PLA, ~110 W on ABS (vendor spec — community data still thin)

Creality K1 / K1C / K1 Max: community data thin — estimate 80–200 W

Creality K2 Plus: no clean community number surfaced yet

Voron 2.4 / Trident (350mm class): ~200–250 W (no chamber heater)

If your printer isn't on the list, two options. Buy a smart plug or Kill-A-Watt for $15 and measure it yourself — I'd recommend this regardless, it's the most accurate number you'll ever get. Or use the nameplate wattage divided by three as a rough estimate. Nameplate-over-three is a community rule of thumb that lands close to measured average for most consumer FDM printers.

Bonus: once you've measured one print, the number stays pretty stable across similar prints on the same machine. You don't have to measure every job. Measure once, plug into Margin Forge, move on.

Printer depreciation — the math nobody wants to do

This is the cost of your printer wearing out, prorated across each print. It's real. Nozzles wear, belts stretch, hotends clog, boards fry, fans die. Every print is a tiny percentage of your printer's eventual death. You need to charge for that.

The maker-community method is straightforward — depreciation per hour over expected lifetime hours:

$ per hour wear = Printer cost ÷ Expected lifetime hours

Then multiply by the print's run time. Done.

The two inputs:

Printer cost

is whatever you paid. Include shipping and any required accessories (build plate, enclosure if you bought one).

Expected lifetime hours

is where people get stuck. Community consensus is 5,000 hours as a conservative default, with well-maintained machines reaching 7,500–10,000+. Prusa community threads cite 10,000 hours as a board-component lifetime estimate. If you maintain your printer well — replace nozzles, keep rails clean, swap belts before they snap — you can defend the high end. If you're a market vendor running prints back-to-back, use the conservative number.

My take: start at 5,000 hours unless you've been running a printer hard for years with no issues — then you can defend 7,500 or 10,000. Conservative numbers protect you. The worst that happens with a conservative depreciation rate is your prints cost slightly more on paper than they really did. The worst with an aggressive rate is you discover too late that your real margin is half of what you thought.

Worked example with round numbers: a $1,200 printer divided by 5,000 hours = $0.24/hour of wear. A six-hour print eats $1.44 of printer life. That number goes straight into Margin Forge.

What about taxes?

Honestly, this is where I tap out and let my accountant handle the year-end side. For the IRS, you depreciate over 5 or 7 years using MACRS. Or you take the full deduction in year one under Section 179 — the current cap is well above any 3D printer's price. Those are tax decisions — they affect your tax bill, not your per-print cost.

For pricing a print, stick with the per-hour method. The tax math runs separately at year-end with your accountant.

What about maintenance?

Honest answer — most makers roll maintenance into the depreciation number by using a conservative lifetime estimate. That's the "5,000 hours instead of 10,000" choice I made above. Some operators track it separately as $0.05–$0.10 per hour on top. Either approach works. Pick one and stick with it.

A worked example, end to end

Let's run one print end-to-end. Round numbers, real math.

Print: A six-hour poster on a Bambu P1S.

Electricity:

50 W average during print = 0.05 kW

0.05 kW × 6 hours = 0.3 kWh

0.3 kWh × $0.15/kWh = $0.045 electricity

Depreciation:

$700 printer ÷ 5,000 hr lifetime = $0.14/hour

$0.14 × 6 hours = $0.84 wear

Hidden cost total: ~$0.89 on top of filament.

If your filament is $5 for that print, you were costing it at $5. The real cost is closer to $5.89. Not catastrophic on a single print — but multiply it across a month of selling, and that's $30–$80 of margin you weren't accounting for. Across a full booth at a market, it's the difference between barely covering booth fees and walking away with real profit.

This is the math that runs inside Margin Forge now, every time you log a print.

Common pitfalls

You used nameplate wattage.

If you typed 350 W into Margin Forge for a printer that draws 100 W average, your electricity cost is 3.5× too high and you'll panic for no reason. Use the measured average.

You forgot to update depreciation when you bought a new printer.

Each printer in Margin Forge has its own depreciation rate. The A1 mini and the X1C aren't the same number.

You're plugging in the wrong rate.

If your utility has TOU pricing and you print overnight at off-peak rates, use the off-peak rate. Plugging in the peak rate makes electricity look 2–3× worse than it is.

Plug the numbers in

Both fields are live in Margin Forge under your printer setup. Open the Printers page, click your printer, fill in the average wattage and the depreciation per hour. From that point on, every design tied to that printer pulls those numbers into the margin calculation automatically. No spreadsheet, no recalculating, no forgetting.

If you've already been running Margin Forge at markets without these fields filled in, take ten minutes and update them now. Your margin numbers are about to get more honest. Some of them might get uglier. I love that — the green number on the dashboard means more when it accounts for everything.

Pricing prints honestly is the foundation of every other business decision you'll make. Which designs to keep running. Which markets are worth driving to. When to raise prices. When to retire a SKU. Margin Forge runs that math for you, but only if you give it the right inputs. Now you know what those inputs are.

What's your kWh rate, y'all? Drop it in the Discord — I'm curious where everyone lands. I'm betting we've got people from $0.09 Midwest territory all the way up to $0.45 California rates. That range tells a real story about who can run what at a profit.

And if you haven't seen the canonical breakdown of how I price prints at markets, the 3 biggest problems with selling HueForge prints is the YouTube walk-through.

Take care.

Thank y'all so much — I appreciate every single one of you.

Catch you in the next one.

— Vic