Ask what interior design software costs and you'll get the subscription price — $55 to $119 a user, for most of the category. But if you invoice clients through your software (and that's the point of most of these tools), there's a second price: the payment-processing fee on every dollar that moves. On a $40,000 procurement invoice, the difference between fee schedules is real money — and it's the number vendors are least willing to print.
We researched both numbers for ten platforms, from primary sources, in July 2026. Here's the whole table, followed by what to actually do with it. Prices change; check the linked vendor pages before deciding.
The full cost table (July 2026)
Tool | Subscription (published) | Card fees | Bank transfer / ACH fees | Where fees are disclosed |
|---|---|---|---|---|
Mortar | $59/user/mo, unlimited projects, no onboarding fee | 3.3% + 30¢ | 0.4%, min $1, capped at $15 | On the pricing page, including Mortar's share |
DesignFiles | $55 or $75/mo, +$30/user | 2.9% + 30¢ (Stripe at cost) | ~0.8% (Full Service plan only) | Help docs only |
Mydoma Studio | $58/user/mo billed yearly, + $300 onboarding | 2.9% + 30¢ + ~1% gateway fee | Supported; help docs | Help docs / payment-terms page |
Programa | $71/mo incl. 1 seat, +$31/seat | Not published | Not published | Not on the pricing page ("no surprise fees" language, no rates) |
Design Manager | $79/user/mo | 3.1% | 1.2% | A marketing blog post — not pricing or help pages |
Studio Designer | $69–$119/user/mo (tier + billing cycle) | 3.25% + 60¢ (fixed) | 0.5% capped at $25, + $4 return / $10 dispute fees | Help-center articles only |
Houzz Pro | Quote-gated; extra users $60/user/mo is the only published number | Published only inside image files | ~1%; $100 cap on "certain packages" only | Among the worst — images and support tickets |
Materio | $115–$495/mo, project-capacity based | 3.65% | 0.8% capped at $30; $50 disputes | Help center |
Gather | $99 or $199/mo, +$39/seat | No payment collection | No payment collection | N/A — pushes invoices to QuickBooks |
Fohlio | No public pricing (demo request only) | No payment collection | No payment collection | N/A |
All figures from vendor pricing pages and help documentation, fetched July 2026. Houzz Pro's base price is quote-gated (third-party listings suggest around $399/mo for the entry tier, but Houzz doesn't publish it); Programa's processing rates aren't published anywhere we could verify, so we won't guess them here.
The subscription is the predictable half
The core band is tight: roughly $55–$79 per user per month buys you a serious tool. Watch the structural differences more than the sticker:
- Onboarding fees. Mydoma adds a one-time $300 to every new account. Nobody else in the core band charges one.
- Base-plus-seat maths. Programa is $71 for the first seat but $31 for each extra; DesignFiles adds $30 a user on top of the plan. Model your actual headcount, not the headline.
- Project caps. Materio is the only tool here that meters projects, with paid packs to add more. Everyone else is unlimited — treat that as the standard.
- Tier gating. DesignFiles reserves ACH payments and full invoicing for its $75 plan. Studio Designer, credit where due, includes payments and full accounting on every tier.
The payment fees are the half that scales with your business
A design studio moving $500,000 a year through its software cares a lot about the difference between an 0.4% capped bank-transfer fee and an uncapped 1%. Three things stand out from the table:
Almost nobody publishes rates where you'd look. Not one competitor puts processing fees on its pricing page. The best case is help-center articles; the worst is Houzz Pro, where the rates live inside image files, with fee caps that vary by subscription package. If you're evaluating tools, ask for the fee schedule in writing before you sign — a vendor's willingness to answer is itself information.
ACH caps are where big invoices are won. On a $40,000 invoice, an uncapped 1% gateway costs $400. Studio Designer's capped ACH costs $25. Mortar's costs $15. If your projects run five and six figures, the ACH cap matters more than the card rate.
"At cost" exists — so markups are a choice. DesignFiles passes Stripe's rates straight through with no markup, which proves it's possible. Others add margin (Mydoma ~1%, Materio ~0.75 points over Stripe's standard card rate). A margin isn't a scandal — it funds the product — but an undisclosed one means you can't price your own fees to clients accurately.
How to compare honestly (including us)
Mortar is in that table, so read our row with the same scepticism: $59 per user per month, unlimited projects, no onboarding fee; cards at 3.3% + 30¢; bank transfers at 0.4% with a $1 minimum and a $15 cap. The card rate is mid-pack — DesignFiles and Design Manager are cheaper on cards. Where we've deliberately gone hardest is the bank-transfer cap and the disclosure: the full schedule, including the share Mortar keeps, is on our pricing page, not in a help doc.
To pressure-test any tool on this list: put a real project's payment volume against its fee schedule, ask for unpublished rates in writing, and check what happens to your data if you leave. Then run the trial with a live project, not a toy one.
For the deeper feature-by-feature view, see our full 2026 roundup of interior design project management software.
